It has been observed, that highly-threaded, non-cpu-bound applications
running under cpu.cfs_quota_us constraints can hit a high percentage of
periods throttled while simultaneously not consuming the allocated
amount of quota. This use case is typical of user-interactive non-cpu
bound applications, such as those running in kubernetes or mesos when
run on multiple cpu cores.
This has been root caused to cpu-local run queue being allocated per cpu
bandwidth slices, and then not fully using that slice within the period.
At which point the slice and quota expires. This expiration of unused
slice results in applications not being able to utilize the quota for
which they are allocated.
The non-expiration of per-cpu slices was recently fixed by
'commit 512ac999d2 ("sched/fair: Fix bandwidth timer clock drift
condition")'. Prior to that it appears that this had been broken since
at least 'commit 51f2176d74 ("sched/fair: Fix unlocked reads of some
cfs_b->quota/period")' which was introduced in v3.16-rc1 in 2014. That
added the following conditional which resulted in slices never being
expired.
if (cfs_rq->runtime_expires != cfs_b->runtime_expires) {
/* extend local deadline, drift is bounded above by 2 ticks */
cfs_rq->runtime_expires += TICK_NSEC;
Because this was broken for nearly 5 years, and has recently been fixed
and is now being noticed by many users running kubernetes
(https://github.com/kubernetes/kubernetes/issues/67577) it is my opinion
that the mechanisms around expiring runtime should be removed
altogether.
This allows quota already allocated to per-cpu run-queues to live longer
than the period boundary. This allows threads on runqueues that do not
use much CPU to continue to use their remaining slice over a longer
period of time than cpu.cfs_period_us. However, this helps prevent the
above condition of hitting throttling while also not fully utilizing
your cpu quota.
This theoretically allows a machine to use slightly more than its
allotted quota in some periods. This overflow would be bounded by the
remaining quota left on each per-cpu runqueueu. This is typically no
more than min_cfs_rq_runtime=1ms per cpu. For CPU bound tasks this will
change nothing, as they should theoretically fully utilize all of their
quota in each period. For user-interactive tasks as described above this
provides a much better user/application experience as their cpu
utilization will more closely match the amount they requested when they
hit throttling. This means that cpu limits no longer strictly apply per
period for non-cpu bound applications, but that they are still accurate
over longer timeframes.
This greatly improves performance of high-thread-count, non-cpu bound
applications with low cfs_quota_us allocation on high-core-count
machines. In the case of an artificial testcase (10ms/100ms of quota on
80 CPU machine), this commit resulted in almost 30x performance
improvement, while still maintaining correct cpu quota restrictions.
That testcase is available at https://github.com/indeedeng/fibtest.
Fixes: 512ac999d2 ("sched/fair: Fix bandwidth timer clock drift condition")
Signed-off-by: Dave Chiluk <chiluk+linux@indeed.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Hammond <jhammond@indeed.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kyle Anderson <kwa@yelp.com>
Cc: Gabriel Munos <gmunoz@netflix.com>
Cc: Peter Oskolkov <posk@posk.io>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Brendan Gregg <bgregg@netflix.com>
Link: https://lkml.kernel.org/r/1563900266-19734-2-git-send-email-chiluk+linux@indeed.com
The current active_mm reference counting is confusing and sub-optimal.
Rewrite the code to explicitly consider the 4 separate cases:
user -> user
When switching between two user tasks, all we need to consider
is switch_mm().
user -> kernel
When switching from a user task to a kernel task (which
doesn't have an associated mm) we retain the last mm in our
active_mm. Increment a reference count on active_mm.
kernel -> kernel
When switching between kernel threads, all we need to do is
pass along the active_mm reference.
kernel -> user
When switching between a kernel and user task, we must switch
from the last active_mm to the next mm, hoping of course that
these are the same. Decrement a reference on the active_mm.
The code keeps a different order, because as you'll note, both 'to
user' cases require switch_mm().
And where the old code would increment/decrement for the 'kernel ->
kernel' case, the new code observes this is a neutral operation and
avoids touching the reference count.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: luto@kernel.org
When a process creates a new trigger by writing into /proc/pressure/*
files, permissions to write such a file should be used to determine whether
the process is allowed to do so or not. Current implementation would also
require such a process to have setsched capability. Setting of psi trigger
thread's scheduling policy is an implementation detail and should not be
exposed to the user level. Remove the permission check by using _nocheck
version of the function.
Suggested-by: Nick Kralevich <nnk@google.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: lizefan@huawei.com
Cc: mingo@redhat.com
Cc: akpm@linux-foundation.org
Cc: kernel-team@android.com
Cc: dennisszhou@gmail.com
Cc: dennis@kernel.org
Cc: hannes@cmpxchg.org
Cc: axboe@kernel.dk
Link: https://lkml.kernel.org/r/20190730013310.162367-1-surenb@google.com
PSI defaults to a FIFO-99 thread, reduce this to FIFO-1.
FIFO-99 is the very highest priority available to SCHED_FIFO and
it not a suitable default; it would indicate the psi work is the
most important work on the machine.
Since Real-Time tasks will have pre-allocated memory and locked it in
place, Real-Time tasks do not care about PSI. All it needs is to be
above OTHER.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
The TASKS03 and TREE04 rcutorture scenarios produce the following
lockdep complaint:
------------------------------------------------------------------------
================================
WARNING: inconsistent lock state
5.2.0-rc1+ #513 Not tainted
--------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
migration/1/14 [HC0[0]:SC0[0]:HE1:SE1] takes:
(____ptrval____) (tick_broadcast_lock){?...}, at: tick_broadcast_offline+0xf/0x70
{IN-HARDIRQ-W} state was registered at:
lock_acquire+0xb0/0x1c0
_raw_spin_lock_irqsave+0x3c/0x50
tick_broadcast_switch_to_oneshot+0xd/0x40
tick_switch_to_oneshot+0x4f/0xd0
hrtimer_run_queues+0xf3/0x130
run_local_timers+0x1c/0x50
update_process_times+0x1c/0x50
tick_periodic+0x26/0xc0
tick_handle_periodic+0x1a/0x60
smp_apic_timer_interrupt+0x80/0x2a0
apic_timer_interrupt+0xf/0x20
_raw_spin_unlock_irqrestore+0x4e/0x60
rcu_nocb_gp_kthread+0x15d/0x590
kthread+0xf3/0x130
ret_from_fork+0x3a/0x50
irq event stamp: 171
hardirqs last enabled at (171): [<ffffffff8a201a37>] trace_hardirqs_on_thunk+0x1a/0x1c
hardirqs last disabled at (170): [<ffffffff8a201a53>] trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last enabled at (0): [<ffffffff8a264ee0>] copy_process.part.56+0x650/0x1cb0
softirqs last disabled at (0): [<0000000000000000>] 0x0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(tick_broadcast_lock);
<Interrupt>
lock(tick_broadcast_lock);
*** DEADLOCK ***
1 lock held by migration/1/14:
#0: (____ptrval____) (clockevents_lock){+.+.}, at: tick_offline_cpu+0xf/0x30
stack backtrace:
CPU: 1 PID: 14 Comm: migration/1 Not tainted 5.2.0-rc1+ #513
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS Bochs 01/01/2011
Call Trace:
dump_stack+0x5e/0x8b
print_usage_bug+0x1fc/0x216
? print_shortest_lock_dependencies+0x1b0/0x1b0
mark_lock+0x1f2/0x280
__lock_acquire+0x1e0/0x18f0
? __lock_acquire+0x21b/0x18f0
? _raw_spin_unlock_irqrestore+0x4e/0x60
lock_acquire+0xb0/0x1c0
? tick_broadcast_offline+0xf/0x70
_raw_spin_lock+0x33/0x40
? tick_broadcast_offline+0xf/0x70
tick_broadcast_offline+0xf/0x70
tick_offline_cpu+0x16/0x30
take_cpu_down+0x7d/0xa0
multi_cpu_stop+0xa2/0xe0
? cpu_stop_queue_work+0xc0/0xc0
cpu_stopper_thread+0x6d/0x100
smpboot_thread_fn+0x169/0x240
kthread+0xf3/0x130
? sort_range+0x20/0x20
? kthread_cancel_delayed_work_sync+0x10/0x10
ret_from_fork+0x3a/0x50
------------------------------------------------------------------------
To reproduce, run the following rcutorture test:
tools/testing/selftests/rcutorture/bin/kvm.sh --duration 5 --kconfig "CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y" --configs "TASKS03 TREE04"
It turns out that tick_broadcast_offline() was an innocent bystander.
After all, interrupts are supposed to be disabled throughout
take_cpu_down(), and therefore should have been disabled upon entry to
tick_offline_cpu() and thus to tick_broadcast_offline(). This suggests
that one of the CPU-hotplug notifiers was incorrectly enabling interrupts,
and leaving them enabled on return.
Some debugging code showed that the culprit was sched_cpu_dying().
It had irqs enabled after return from sched_tick_stop(). Which in turn
had irqs enabled after return from cancel_delayed_work_sync(). Which is a
wrapper around __cancel_work_timer(). Which can sleep in the case where
something else is concurrently trying to cancel the same delayed work,
and as Thomas Gleixner pointed out on IRC, sleeping is a decidedly bad
idea when you are invoked from take_cpu_down(), regardless of the state
you leave interrupts in upon return.
Code inspection located no reason why the delayed work absolutely
needed to be canceled from sched_tick_stop(): The work is not
bound to the outgoing CPU by design, given that the whole point is
to collect statistics without disturbing the outgoing CPU.
This commit therefore simply drops the cancel_delayed_work_sync() from
sched_tick_stop(). Instead, a new ->state field is added to the tick_work
structure so that the delayed-work handler function sched_tick_remote()
can avoid reposting itself. A cpu_is_offline() check is also added to
sched_tick_remote() to avoid mucking with the state of an offlined CPU
(though it does appear safe to do so). The sched_tick_start() and
sched_tick_stop() functions also update ->state, and sched_tick_start()
also schedules the delayed work if ->state indicates that it is not
already in flight.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
[ paulmck: Apply Peter Zijlstra and Frederic Weisbecker atomics feedback. ]
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
SCHED_DEADLINE inactive timer needs to run in hardirq context (as
dl_task_timer already does) on PREEMPT_RT
Change the mode to HRTIMER_MODE_REL_HARD.
[ tglx: Fixed up the start site, so mode debugging works ]
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190731103715.4047-1-juri.lelli@redhat.com
The scheduler related hrtimers need to expire in hard interrupt context
even on PREEMPT_RT enabled kernels. Mark then as such.
No functional change.
[ tglx: Split out from larger combo patch. Add changelog. ]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185753.077004842@linutronix.de
CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by
CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same
functionality which today depends on CONFIG_PREEMPT.
Switch the preemption code, scheduler and init task over to use
CONFIG_PREEMPTION.
That's the first step towards RT in that area. The more complex changes are
coming separately.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20190726212124.117528401@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Compiling a kernel with both FAIR_GROUP_SCHED=n and RT_GROUP_SCHED=n
will generate a compiler warning:
kernel/sched/core.c: In function 'sched_init':
kernel/sched/core.c:5906:32: warning: variable 'ptr' set but not used
It is unnecessary to have both "alloc_size" and "ptr", so just combine
them.
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: valentin.schneider@arm.com
Link: https://lkml.kernel.org/r/20190720012319.884-1-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On !CONFIG_RT_GROUP_SCHED configurations it is currently not possible to
move RT tasks between cgroups to which CPU controller has been attached;
but it is oddly possible to first move tasks around and then make them
RT (setschedule to FIFO/RR).
E.g.:
# mkdir /sys/fs/cgroup/cpu,cpuacct/group1
# chrt -fp 10 $$
# echo $$ > /sys/fs/cgroup/cpu,cpuacct/group1/tasks
bash: echo: write error: Invalid argument
# chrt -op 0 $$
# echo $$ > /sys/fs/cgroup/cpu,cpuacct/group1/tasks
# chrt -fp 10 $$
# cat /sys/fs/cgroup/cpu,cpuacct/group1/tasks
2345
2598
# chrt -p 2345
pid 2345's current scheduling policy: SCHED_FIFO
pid 2345's current scheduling priority: 10
Also, as Michal noted, it is currently not possible to enable CPU
controller on unified hierarchy with !CONFIG_RT_GROUP_SCHED (if there
are any kernel RT threads in root cgroup, they can't be migrated to the
newly created CPU controller's root in cgroup_update_dfl_csses()).
Existing code comes with a comment saying the "we don't support RT-tasks
being in separate groups". Such comment is however stale and belongs to
pre-RT_GROUP_SCHED times. Also, it doesn't make much sense for
!RT_GROUP_ SCHED configurations, since checks related to RT bandwidth
are not performed at all in these cases.
Make moving RT tasks between CPU controller groups viable by removing
special case check for RT (and DEADLINE) tasks.
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: rostedt@goodmis.org
Link: https://lkml.kernel.org/r/20190719063455.27328-1-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
No synchronisation mechanism exists between the cpuset subsystem and
calls to function __sched_setscheduler(). As such, it is possible that
new root domains are created on the cpuset side while a deadline
acceptance test is carried out in __sched_setscheduler(), leading to a
potential oversell of CPU bandwidth.
Grab cpuset_rwsem read lock from core scheduler, so to prevent
situations such as the one described above from happening.
The only exception is normalize_rt_tasks() which needs to work under
tasklist_lock and can't therefore grab cpuset_rwsem. We are fine with
this, as this function is only called by sysrq and, if that gets
triggered, DEADLINE guarantees are already gone out of the window
anyway.
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: mathieu.poirier@linaro.org
Cc: rostedt@goodmis.org
Cc: tj@kernel.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-9-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the topology of root domains is modified by CPUset or CPUhotplug
operations information about the current deadline bandwidth held in the
root domain is lost.
This patch addresses the issue by recalculating the lost deadline
bandwidth information by circling through the deadline tasks held in
CPUsets and adding their current load to the root domain they are
associated with.
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
[ Various additional modifications. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: rostedt@goodmis.org
Cc: tj@kernel.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-4-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Calls to task_rq_unlock() are done several times in the
__sched_setscheduler() function. This is fine when only the rq lock needs to be
handled but not so much when other locks come into play.
This patch streamlines the release of the rq lock so that only one
location need to be modified when dealing with more than one lock.
No change of functionality is introduced by this patch.
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-3-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Introduce the partition_sched_domains_locked() function by taking
the mutex locking code out of the original function. That way
the work done by partition_sched_domains_locked() can be reused
without dropping the mutex lock.
No change of functionality is introduced by this patch.
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: rostedt@goodmis.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-2-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The same formula to check utilization against capacity (after
considering capacity_margin) is already used at 5 different locations.
This patch creates a new macro, fits_capacity(), which can be used from
all these locations without exposing the details of it and hence
simplify code.
All the 5 code locations are updated as well to use it..
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/b477ac75a2b163048bdaeb37f57b4c3f04f75a31.1559631700.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In real product setup, there will be houseeking CPUs in each nodes, it
is prefer to do housekeeping from local node, fallback to global online
cpumask if failed to find houseeking CPU from local node.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1561711901-4755-2-git-send-email-wanpengli@tencent.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched_info_on() is called with unlikely hint, however, the test
is to be a constant(1) on which compiler will do nothing when
make defconfig, so remove the hint.
Also, fix a lack of {}.
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: up2wing@gmail.com
Cc: wang.liang82@zte.com.cn
Cc: xue.zhihong@zte.com.cn
Link: https://lkml.kernel.org/r/1562301307-43002-1-git-send-email-wang.yi59@zte.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We try to find an idle CPU to run the next task, but in case we don't
find an idle CPU it is better to pick a CPU which will run the task the
soonest, for performance reason.
A CPU which isn't idle but has only SCHED_IDLE activity queued on it
should be a good target based on this criteria as any normal fair task
will most likely preempt the currently running SCHED_IDLE task
immediately. In fact, choosing a SCHED_IDLE CPU over a fully idle one
shall give better results as it should be able to run the task sooner
than an idle CPU (which requires to be woken up from an idle state).
This patch updates both fast and slow paths with this optimization.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: chris.redpath@arm.com
Cc: quentin.perret@linaro.org
Cc: songliubraving@fb.com
Cc: steven.sistare@oracle.com
Cc: subhra.mazumdar@oracle.com
Cc: tkjos@google.com
Link: https://lkml.kernel.org/r/eeafa25fdeb6f6edd5b2da716bc8f0ba7708cbcf.1561523542.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
time/tick-broadcast: Fix tick_broadcast_offline() lockdep complaint
The TASKS03 and TREE04 rcutorture scenarios produce the following
lockdep complaint:
WARNING: inconsistent lock state
5.2.0-rc1+ #513 Not tainted
--------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
migration/1/14 [HC0[0]:SC0[0]:HE1:SE1] takes:
(____ptrval____) (tick_broadcast_lock){?...}, at: tick_broadcast_offline+0xf/0x70
{IN-HARDIRQ-W} state was registered at:
lock_acquire+0xb0/0x1c0
_raw_spin_lock_irqsave+0x3c/0x50
tick_broadcast_switch_to_oneshot+0xd/0x40
tick_switch_to_oneshot+0x4f/0xd0
hrtimer_run_queues+0xf3/0x130
run_local_timers+0x1c/0x50
update_process_times+0x1c/0x50
tick_periodic+0x26/0xc0
tick_handle_periodic+0x1a/0x60
smp_apic_timer_interrupt+0x80/0x2a0
apic_timer_interrupt+0xf/0x20
_raw_spin_unlock_irqrestore+0x4e/0x60
rcu_nocb_gp_kthread+0x15d/0x590
kthread+0xf3/0x130
ret_from_fork+0x3a/0x50
irq event stamp: 171
hardirqs last enabled at (171): [<ffffffff8a201a37>] trace_hardirqs_on_thunk+0x1a/0x1c
hardirqs last disabled at (170): [<ffffffff8a201a53>] trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last enabled at (0): [<ffffffff8a264ee0>] copy_process.part.56+0x650/0x1cb0
softirqs last disabled at (0): [<0000000000000000>] 0x0
[...]
To reproduce, run the following rcutorture test:
$ tools/testing/selftests/rcutorture/bin/kvm.sh --duration 5 --kconfig "CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y" --configs "TASKS03 TREE04"
It turns out that tick_broadcast_offline() was an innocent bystander.
After all, interrupts are supposed to be disabled throughout
take_cpu_down(), and therefore should have been disabled upon entry to
tick_offline_cpu() and thus to tick_broadcast_offline(). This suggests
that one of the CPU-hotplug notifiers was incorrectly enabling interrupts,
and leaving them enabled on return.
Some debugging code showed that the culprit was sched_cpu_dying().
It had irqs enabled after return from sched_tick_stop(). Which in turn
had irqs enabled after return from cancel_delayed_work_sync(). Which is a
wrapper around __cancel_work_timer(). Which can sleep in the case where
something else is concurrently trying to cancel the same delayed work,
and as Thomas Gleixner pointed out on IRC, sleeping is a decidedly bad
idea when you are invoked from take_cpu_down(), regardless of the state
you leave interrupts in upon return.
Code inspection located no reason why the delayed work absolutely
needed to be canceled from sched_tick_stop(): The work is not
bound to the outgoing CPU by design, given that the whole point is
to collect statistics without disturbing the outgoing CPU.
This commit therefore simply drops the cancel_delayed_work_sync() from
sched_tick_stop(). Instead, a new ->state field is added to the tick_work
structure so that the delayed-work handler function sched_tick_remote()
can avoid reposting itself. A cpu_is_offline() check is also added to
sched_tick_remote() to avoid mucking with the state of an offlined CPU
(though it does appear safe to do so). The sched_tick_start() and
sched_tick_stop() functions also update ->state, and sched_tick_start()
also schedules the delayed work if ->state indicates that it is not
already in flight.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Apply Peter Zijlstra and Frederic Weisbecker atomics feedback. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190625165238.GJ26519@linux.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The load_balance() has a dedicated mecanism to detect when an imbalance
is due to CPU affinity and must be handled at parent level. In this case,
the imbalance field of the parent's sched_group is set.
The description of sg_imbalanced() gives a typical example of two groups
of 4 CPUs each and 4 tasks each with a cpumask covering 1 CPU of the first
group and 3 CPUs of the second group. Something like:
{ 0 1 2 3 } { 4 5 6 7 }
* * * *
But the load_balance fails to fix this UC on my octo cores system
made of 2 clusters of quad cores.
Whereas the load_balance is able to detect that the imbalanced is due to
CPU affinity, it fails to fix it because the imbalance field is cleared
before letting parent level a chance to run. In fact, when the imbalance is
detected, the load_balance reruns without the CPU with pinned tasks. But
there is no other running tasks in the situation described above and
everything looks balanced this time so the imbalance field is immediately
cleared.
The imbalance field should not be cleared if there is no other task to move
when the imbalance is detected.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1561996022-28829-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We only need to set the callback_head worker function once, do it
during sched_fork().
While at it, move the comment regarding double task_work addition to
init_numa_balancing(), since the double add sentinel is first set there.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mgorman@suse.de
Cc: riel@surriel.com
Link: https://lkml.kernel.org/r/20190715102508.32434-3-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
To reference task_numa_work() from within init_numa_balancing(), we
need the former to be declared before the latter. Do just that.
This is a pure code movement.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mgorman@suse.de
Cc: riel@surriel.com
Link: https://lkml.kernel.org/r/20190715102508.32434-2-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The old code used RCU annotations and accessors inconsistently for
->numa_group, which can lead to use-after-frees and NULL dereferences.
Let all accesses to ->numa_group use proper RCU helpers to prevent such
issues.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Fixes: 8c8a743c50 ("sched/numa: Use {cpu, pid} to create task groups for shared faults")
Link: https://lkml.kernel.org/r/20190716152047.14424-3-jannh@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When going through execve(), zero out the NUMA fault statistics instead of
freeing them.
During execve, the task is reachable through procfs and the scheduler. A
concurrent /proc/*/sched reader can read data from a freed ->numa_faults
allocation (confirmed by KASAN) and write it back to userspace.
I believe that it would also be possible for a use-after-free read to occur
through a race between a NUMA fault and execve(): task_numa_fault() can
lead to task_numa_compare(), which invokes task_weight() on the currently
running task of a different CPU.
Another way to fix this would be to make ->numa_faults RCU-managed or add
extra locking, but it seems easier to wipe the NUMA fault statistics on
execve.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Fixes: 82727018b0 ("sched/numa: Call task_numa_free() from do_execve()")
Link: https://lkml.kernel.org/r/20190716152047.14424-1-jannh@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
- s390 support for KVM selftests
- LAPIC timer offloading to housekeeping CPUs
- Extend an s390 optimization for overcommitted hosts to all architectures
- Debugging cleanups and improvements
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.22 (GNU/Linux)
iQEcBAABAgAGBQJdMr1FAAoJEL/70l94x66DvIkH/iVuUX9jO1NoQ7qhxeo04MnT
GP9mX3XnWoI/iN0zAIRfQSP2/9a6+KblgdiziABhju58j5dCfAZGb5793TQppweb
3ubl11vy7YkzaXJ0b35K7CFhOU9oSlHHGyi5Uh+yyje5qWNxwmHpizxjynbFTKb6
+/S7O2Ua1VrAVvx0i0IRtwanIK/jF4dStVButgVaVdUva3zLaQmeI71iaJl9ddXY
bh50xoYua5Ek6+ENi+nwCNVy4OF152AwDbXlxrU0QbeA1B888Qio7nIqb3bwwPpZ
/8wMVvPzQgL7RmgtY5E5Z4cCYuu7mK8wgGxhuk3oszlVwZJ5rmnaYwGEl4x1s7o=
=giag
-----END PGP SIGNATURE-----
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull more KVM updates from Paolo Bonzini:
"Mostly bugfixes, but also:
- s390 support for KVM selftests
- LAPIC timer offloading to housekeeping CPUs
- Extend an s390 optimization for overcommitted hosts to all
architectures
- Debugging cleanups and improvements"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (25 commits)
KVM: x86: Add fixed counters to PMU filter
KVM: nVMX: do not use dangling shadow VMCS after guest reset
KVM: VMX: dump VMCS on failed entry
KVM: x86/vPMU: refine kvm_pmu err msg when event creation failed
KVM: s390: Use kvm_vcpu_wake_up in kvm_s390_vcpu_wakeup
KVM: Boost vCPUs that are delivering interrupts
KVM: selftests: Remove superfluous define from vmx.c
KVM: SVM: Fix detection of AMD Errata 1096
KVM: LAPIC: Inject timer interrupt via posted interrupt
KVM: LAPIC: Make lapic timer unpinned
KVM: x86/vPMU: reset pmc->counter to 0 for pmu fixed_counters
KVM: nVMX: Ignore segment base for VMX memory operand when segment not FS or GS
kvm: x86: ioapic and apic debug macros cleanup
kvm: x86: some tsc debug cleanup
kvm: vmx: fix coccinelle warnings
x86: kvm: avoid constant-conversion warning
x86: kvm: avoid -Wsometimes-uninitized warning
KVM: x86: expose AVX512_BF16 feature to guest
KVM: selftests: enable pgste option for the linker on s390
KVM: selftests: Move kvm_create_max_vcpus test to generic code
...
Dedicated instances are currently disturbed by unnecessary jitter due
to the emulated lapic timers firing on the same pCPUs where the
vCPUs reside. There is no hardware virtual timer on Intel for guest
like ARM, so both programming timer in guest and the emulated timer fires
incur vmexits. This patch tries to avoid vmexit when the emulated timer
fires, at least in dedicated instance scenario when nohz_full is enabled.
In that case, the emulated timers can be offload to the nearest busy
housekeeping cpus since APICv has been found for several years in server
processors. The guest timer interrupt can then be injected via posted interrupts,
which are delivered by the housekeeping cpu once the emulated timer fires.
The host should tuned so that vCPUs are placed on isolated physical
processors, and with several pCPUs surplus for busy housekeeping.
If disabled mwait/hlt/pause vmexits keep the vCPUs in non-root mode,
~3% redis performance benefit can be observed on Skylake server, and the
number of external interrupt vmexits drops substantially. Without patch
VM-EXIT Samples Samples% Time% Min Time Max Time Avg time
EXTERNAL_INTERRUPT 42916 49.43% 39.30% 0.47us 106.09us 0.71us ( +- 1.09% )
While with patch:
VM-EXIT Samples Samples% Time% Min Time Max Time Avg time
EXTERNAL_INTERRUPT 6871 9.29% 2.96% 0.44us 57.88us 0.72us ( +- 4.02% )
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
John reported a DEBUG_PREEMPT warning caused by commit:
aacedf26fb ("sched/core: Optimize try_to_wake_up() for local wakeups")
I overlooked that ttwu_stat() requires preemption disabled.
Reported-by: John Stultz <john.stultz@linaro.org>
Tested-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: aacedf26fb ("sched/core: Optimize try_to_wake_up() for local wakeups")
Link: https://lkml.kernel.org/r/20190710105736.GK3402@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
- A fair pile of RST conversions, many from Mauro. These create more
than the usual number of simple but annoying merge conflicts with other
trees, unfortunately. He has a lot more of these waiting on the wings
that, I think, will go to you directly later on.
- A new document on how to use merges and rebases in kernel repos, and one
on Spectre vulnerabilities.
- Various improvements to the build system, including automatic markup of
function() references because some people, for reasons I will never
understand, were of the opinion that :c:func:``function()`` is
unattractive and not fun to type.
- We now recommend using sphinx 1.7, but still support back to 1.4.
- Lots of smaller improvements, warning fixes, typo fixes, etc.
-----BEGIN PGP SIGNATURE-----
iQFDBAABCAAtFiEEIw+MvkEiF49krdp9F0NaE2wMflgFAl0krAEPHGNvcmJldEBs
d24ubmV0AAoJEBdDWhNsDH5Yg98H/AuLqO9LpOgUjF4LhyjxGPdzJkY9RExSJ7km
gznyreLCZgFaJR+AY6YDsd4Jw6OJlPbu1YM/Qo3C3WrZVFVhgL/s2ebvBgCo50A8
raAFd8jTf4/mGCHnAqRotAPQ3mETJUk315B66lBJ6Oc+YdpRhwXWq8ZW2bJxInFF
3HDvoFgMf0KhLuMHUkkL0u3fxH1iA+KvDu8diPbJYFjOdOWENz/CV8wqdVkXRSEW
DJxIq89h/7d+hIG3d1I7Nw+gibGsAdjSjKv4eRKauZs4Aoxd1Gpl62z0JNk6aT3m
dtq4joLdwScydonXROD/Twn2jsu4xYTrPwVzChomElMowW/ZBBY=
=D0eO
-----END PGP SIGNATURE-----
Merge tag 'docs-5.3' of git://git.lwn.net/linux
Pull Documentation updates from Jonathan Corbet:
"It's been a relatively busy cycle for docs:
- A fair pile of RST conversions, many from Mauro. These create more
than the usual number of simple but annoying merge conflicts with
other trees, unfortunately. He has a lot more of these waiting on
the wings that, I think, will go to you directly later on.
- A new document on how to use merges and rebases in kernel repos,
and one on Spectre vulnerabilities.
- Various improvements to the build system, including automatic
markup of function() references because some people, for reasons I
will never understand, were of the opinion that
:c:func:``function()`` is unattractive and not fun to type.
- We now recommend using sphinx 1.7, but still support back to 1.4.
- Lots of smaller improvements, warning fixes, typo fixes, etc"
* tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits)
docs: automarkup.py: ignore exceptions when seeking for xrefs
docs: Move binderfs to admin-guide
Disable Sphinx SmartyPants in HTML output
doc: RCU callback locks need only _bh, not necessarily _irq
docs: format kernel-parameters -- as code
Doc : doc-guide : Fix a typo
platform: x86: get rid of a non-existent document
Add the RCU docs to the core-api manual
Documentation: RCU: Add TOC tree hooks
Documentation: RCU: Rename txt files to rst
Documentation: RCU: Convert RCU UP systems to reST
Documentation: RCU: Convert RCU linked list to reST
Documentation: RCU: Convert RCU basic concepts to reST
docs: filesystems: Remove uneeded .rst extension on toctables
scripts/sphinx-pre-install: fix out-of-tree build
docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/
Documentation: PGP: update for newer HW devices
Documentation: Add section about CPU vulnerabilities for Spectre
Documentation: platform: Delete x86-laptop-drivers.txt
docs: Note that :c:func: should no longer be used
...
Pull scheduler updates from Ingo Molnar:
- Remove the unused per rq load array and all its infrastructure, by
Dietmar Eggemann.
- Add utilization clamping support by Patrick Bellasi. This is a
refinement of the energy aware scheduling framework with support for
boosting of interactive and capping of background workloads: to make
sure critical GUI threads get maximum frequency ASAP, and to make
sure background processing doesn't unnecessarily move to cpufreq
governor to higher frequencies and less energy efficient CPU modes.
- Add the bare minimum of tracepoints required for LISA EAS regression
testing, by Qais Yousef - which allows automated testing of various
power management features, including energy aware scheduling.
- Restructure the former tsk_nr_cpus_allowed() facility that the -rt
kernel used to modify the scheduler's CPU affinity logic such as
migrate_disable() - introduce the task->cpus_ptr value instead of
taking the address of &task->cpus_allowed directly - by Sebastian
Andrzej Siewior.
- Misc optimizations, fixes, cleanups and small enhancements - see the
Git log for details.
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
sched/uclamp: Add uclamp support to energy_compute()
sched/uclamp: Add uclamp_util_with()
sched/cpufreq, sched/uclamp: Add clamps for FAIR and RT tasks
sched/uclamp: Set default clamps for RT tasks
sched/uclamp: Reset uclamp values on RESET_ON_FORK
sched/uclamp: Extend sched_setattr() to support utilization clamping
sched/core: Allow sched_setattr() to use the current policy
sched/uclamp: Add system default clamps
sched/uclamp: Enforce last task's UCLAMP_MAX
sched/uclamp: Add bucket local max tracking
sched/uclamp: Add CPU's clamp buckets refcounting
sched/fair: Rename weighted_cpuload() to cpu_runnable_load()
sched/debug: Export the newly added tracepoints
sched/debug: Add sched_overutilized tracepoint
sched/debug: Add new tracepoint to track PELT at se level
sched/debug: Add new tracepoints to track PELT at rq level
sched/debug: Add a new sched_trace_*() helper functions
sched/autogroup: Make autogroup_path() always available
sched/wait: Deduplicate code with do-while
sched/topology: Remove unused 'sd' parameter from arch_scale_cpu_capacity()
...
Pull locking updates from Ingo Molnar:
"The main changes in this cycle are:
- rwsem scalability improvements, phase #2, by Waiman Long, which are
rather impressive:
"On a 2-socket 40-core 80-thread Skylake system with 40 reader
and writer locking threads, the min/mean/max locking operations
done in a 5-second testing window before the patchset were:
40 readers, Iterations Min/Mean/Max = 1,807/1,808/1,810
40 writers, Iterations Min/Mean/Max = 1,807/50,344/151,255
After the patchset, they became:
40 readers, Iterations Min/Mean/Max = 30,057/31,359/32,741
40 writers, Iterations Min/Mean/Max = 94,466/95,845/97,098"
There's a lot of changes to the locking implementation that makes
it similar to qrwlock, including owner handoff for more fair
locking.
Another microbenchmark shows how across the spectrum the
improvements are:
"With a locking microbenchmark running on 5.1 based kernel, the
total locking rates (in kops/s) on a 2-socket Skylake system
with equal numbers of readers and writers (mixed) before and
after this patchset were:
# of Threads Before Patch After Patch
------------ ------------ -----------
2 2,618 4,193
4 1,202 3,726
8 802 3,622
16 729 3,359
32 319 2,826
64 102 2,744"
The changes are extensive and the patch-set has been through
several iterations addressing various locking workloads. There
might be more regressions, but unless they are pathological I
believe we want to use this new implementation as the baseline
going forward.
- jump-label optimizations by Daniel Bristot de Oliveira: the primary
motivation was to remove IPI disturbance of isolated RT-workload
CPUs, which resulted in the implementation of batched jump-label
updates. Beyond the improvement of the real-time characteristics
kernel, in one test this patchset improved static key update
overhead from 57 msecs to just 1.4 msecs - which is a nice speedup
as well.
- atomic64_t cross-arch type cleanups by Mark Rutland: over the last
~10 years of atomic64_t existence the various types used by the
APIs only had to be self-consistent within each architecture -
which means they became wildly inconsistent across architectures.
Mark puts and end to this by reworking all the atomic64
implementations to use 's64' as the base type for atomic64_t, and
to ensure that this type is consistently used for parameters and
return values in the API, avoiding further problems in this area.
- A large set of small improvements to lockdep by Yuyang Du: type
cleanups, output cleanups, function return type and othr cleanups
all around the place.
- A set of percpu ops cleanups and fixes by Peter Zijlstra.
- Misc other changes - please see the Git log for more details"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (82 commits)
locking/lockdep: increase size of counters for lockdep statistics
locking/atomics: Use sed(1) instead of non-standard head(1) option
locking/lockdep: Move mark_lock() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING
x86/jump_label: Make tp_vec_nr static
x86/percpu: Optimize raw_cpu_xchg()
x86/percpu, sched/fair: Avoid local_clock()
x86/percpu, x86/irq: Relax {set,get}_irq_regs()
x86/percpu: Relax smp_processor_id()
x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}()
locking/rwsem: Guard against making count negative
locking/rwsem: Adaptive disabling of reader optimistic spinning
locking/rwsem: Enable time-based spinning on reader-owned rwsem
locking/rwsem: Make rwsem->owner an atomic_long_t
locking/rwsem: Enable readers spinning on writer
locking/rwsem: Clarify usage of owner's nonspinaable bit
locking/rwsem: Wake up almost all readers in wait queue
locking/rwsem: More optimal RT task handling of null owner
locking/rwsem: Always release wait_lock before waking up tasks
locking/rwsem: Implement lock handoff to prevent lock starvation
locking/rwsem: Make rwsem_spin_on_owner() return owner state
...
The Energy Aware Scheduler (EAS) estimates the energy impact of waking
up a task on a given CPU. This estimation is based on:
a) an (active) power consumption defined for each CPU frequency
b) an estimation of which frequency will be used on each CPU
c) an estimation of the busy time (utilization) of each CPU
Utilization clamping can affect both b) and c).
A CPU is expected to run:
- on an higher than required frequency, but for a shorter time, in case
its estimated utilization will be smaller than the minimum utilization
enforced by uclamp
- on a smaller than required frequency, but for a longer time, in case
its estimated utilization is bigger than the maximum utilization
enforced by uclamp
While compute_energy() already accounts clamping effects on busy time,
the clamping effects on frequency selection are currently ignored.
Fix it by considering how CPU clamp values will be affected by a
task waking up and being RUNNABLE on that CPU.
Do that by refactoring schedutil_freq_util() to take an additional
task_struct* which allows EAS to evaluate the impact on clamp values of
a task being eventually queued in a CPU. Clamp values are applied to the
RT+CFS utilization only when a FREQUENCY_UTIL is required by
compute_energy().
Do note that switching from ENERGY_UTIL to FREQUENCY_UTIL in the
computation of the cpu_util signal implies that we are more likely to
estimate the highest OPP when a RT task is running in another CPU of
the same performance domain. This can have an impact on energy
estimation but:
- it's not easy to say which approach is better, since it depends on
the use case
- the original approach could still be obtained by setting a smaller
task-specific util_min whenever required
Since we are at that:
- rename schedutil_freq_util() into schedutil_cpu_util(),
since it's not only used for frequency selection.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-12-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So far uclamp_util() allows to clamp a specified utilization considering
the clamp values requested by RUNNABLE tasks in a CPU. For the Energy
Aware Scheduler (EAS) it is interesting to test how clamp values will
change when a task is becoming RUNNABLE on a given CPU.
For example, EAS is interested in comparing the energy impact of
different scheduling decisions and the clamp values can play a role on
that.
Add uclamp_util_with() which allows to clamp a given utilization by
considering the possible impact on CPU clamp values of a specified task.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-11-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Each time a frequency update is required via schedutil, a frequency is
selected to (possibly) satisfy the utilization reported by each
scheduling class and irqs. However, when utilization clamping is in use,
the frequency selection should consider userspace utilization clamping
hints. This will allow, for example, to:
- boost tasks which are directly affecting the user experience
by running them at least at a minimum "requested" frequency
- cap low priority tasks not directly affecting the user experience
by running them only up to a maximum "allowed" frequency
These constraints are meant to support a per-task based tuning of the
frequency selection thus supporting a fine grained definition of
performance boosting vs energy saving strategies in kernel space.
Add support to clamp the utilization of RUNNABLE FAIR and RT tasks
within the boundaries defined by their aggregated utilization clamp
constraints.
Do that by considering the max(min_util, max_util) to give boosted tasks
the performance they need even when they happen to be co-scheduled with
other capped tasks.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-10-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
By default FAIR tasks start without clamps, i.e. neither boosted nor
capped, and they run at the best frequency matching their utilization
demand. This default behavior does not fit RT tasks which instead are
expected to run at the maximum available frequency, if not otherwise
required by explicitly capping them.
Enforce the correct behavior for RT tasks by setting util_min to max
whenever:
1. the task is switched to the RT class and it does not already have a
user-defined clamp value assigned.
2. an RT task is forked from a parent with RESET_ON_FORK set.
NOTE: utilization clamp values are cross scheduling class attributes and
thus they are never changed/reset once a value has been explicitly
defined from user-space.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-9-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A forked tasks gets the same clamp values of its parent however, when
the RESET_ON_FORK flag is set on parent, e.g. via:
sys_sched_setattr()
sched_setattr()
__sched_setscheduler(attr::SCHED_FLAG_RESET_ON_FORK)
the new forked task is expected to start with all attributes reset to
default values.
Do that for utilization clamp values too by checking the reset request
from the existing uclamp_fork() call which already provides the required
initialization for other uclamp related bits.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-8-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The SCHED_DEADLINE scheduling class provides an advanced and formal
model to define tasks requirements that can translate into proper
decisions for both task placements and frequencies selections. Other
classes have a more simplified model based on the POSIX concept of
priorities.
Such a simple priority based model however does not allow to exploit
most advanced features of the Linux scheduler like, for example, driving
frequencies selection via the schedutil cpufreq governor. However, also
for non SCHED_DEADLINE tasks, it's still interesting to define tasks
properties to support scheduler decisions.
Utilization clamping exposes to user-space a new set of per-task
attributes the scheduler can use as hints about the expected/required
utilization for a task. This allows to implement a "proactive" per-task
frequency control policy, a more advanced policy than the current one
based just on "passive" measured task utilization. For example, it's
possible to boost interactive tasks (e.g. to get better performance) or
cap background tasks (e.g. to be more energy/thermal efficient).
Introduce a new API to set utilization clamping values for a specified
task by extending sched_setattr(), a syscall which already allows to
define task specific properties for different scheduling classes. A new
pair of attributes allows to specify a minimum and maximum utilization
the scheduler can consider for a task.
Do that by validating the required clamp values before and then applying
the required changes using _the_ same pattern already in use for
__setscheduler(). This ensures that the task is re-enqueued with the new
clamp values.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-7-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The sched_setattr() syscall mandates that a policy is always specified.
This requires to always know which policy a task will have when
attributes are configured and this makes it impossible to add more
generic task attributes valid across different scheduling policies.
Reading the policy before setting generic tasks attributes is racy since
we cannot be sure it is not changed concurrently.
Introduce the required support to change generic task attributes without
affecting the current task policy. This is done by adding an attribute flag
(SCHED_FLAG_KEEP_POLICY) to enforce the usage of the current policy.
Add support for the SETPARAM_POLICY policy, which is already used by the
sched_setparam() POSIX syscall, to the sched_setattr() non-POSIX
syscall.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-6-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tasks without a user-defined clamp value are considered not clamped
and by default their utilization can have any value in the
[0..SCHED_CAPACITY_SCALE] range.
Tasks with a user-defined clamp value are allowed to request any value
in that range, and the required clamp is unconditionally enforced.
However, a "System Management Software" could be interested in limiting
the range of clamp values allowed for all tasks.
Add a privileged interface to define a system default configuration via:
/proc/sys/kernel/sched_uclamp_util_{min,max}
which works as an unconditional clamp range restriction for all tasks.
With the default configuration, the full SCHED_CAPACITY_SCALE range of
values is allowed for each clamp index. Otherwise, the task-specific
clamp is capped by the corresponding system default value.
Do that by tracking, for each task, the "effective" clamp value and
bucket the task has been refcounted in at enqueue time. This
allows to lazy aggregate "requested" and "system default" values at
enqueue time and simplifies refcounting updates at dequeue time.
The cached bucket ids are used to avoid (relatively) more expensive
integer divisions every time a task is enqueued.
An active flag is used to report when the "effective" value is valid and
thus the task is actually refcounted in the corresponding rq's bucket.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-5-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a task sleeps it removes its max utilization clamp from its CPU.
However, the blocked utilization on that CPU can be higher than the max
clamp value enforced while the task was running. This allows undesired
CPU frequency increases while a CPU is idle, for example, when another
CPU on the same frequency domain triggers a frequency update, since
schedutil can now see the full not clamped blocked utilization of the
idle CPU.
Fix this by using:
uclamp_rq_dec_id(p, rq, UCLAMP_MAX)
uclamp_rq_max_value(rq, UCLAMP_MAX, clamp_value)
to detect when a CPU has no more RUNNABLE clamped tasks and to flag this
condition.
Don't track any minimum utilization clamps since an idle CPU never
requires a minimum frequency. The decay of the blocked utilization is
good enough to reduce the CPU frequency.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-4-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Because of bucketization, different task-specific clamp values are
tracked in the same bucket. For example, with 20% bucket size and
assuming to have:
Task1: util_min=25%
Task2: util_min=35%
both tasks will be refcounted in the [20..39]% bucket and always boosted
only up to 20% thus implementing a simple floor aggregation normally
used in histograms.
In systems with only few and well-defined clamp values, it would be
useful to track the exact clamp value required by a task whenever
possible. For example, if a system requires only 23% and 47% boost
values then it's possible to track the exact boost required by each
task using only 3 buckets of ~33% size each.
Introduce a mechanism to max aggregate the requested clamp values of
RUNNABLE tasks in the same bucket. Keep it simple by resetting the
bucket value to its base value only when a bucket becomes inactive.
Allow a limited and controlled overboosting margin for tasks recounted
in the same bucket.
In systems where the boost values are not known in advance, it is still
possible to control the maximum acceptable overboosting margin by tuning
the number of clamp groups. For example, 20 groups ensure a 5% maximum
overboost.
Remove the rq bucket initialization code since a correct bucket value
is now computed when a task is refcounted into a CPU's rq.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-3-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Utilization clamping allows to clamp the CPU's utilization within a
[util_min, util_max] range, depending on the set of RUNNABLE tasks on
that CPU. Each task references two "clamp buckets" defining its minimum
and maximum (util_{min,max}) utilization "clamp values". A CPU's clamp
bucket is active if there is at least one RUNNABLE tasks enqueued on
that CPU and refcounting that bucket.
When a task is {en,de}queued {on,from} a rq, the set of active clamp
buckets on that CPU can change. If the set of active clamp buckets
changes for a CPU a new "aggregated" clamp value is computed for that
CPU. This is because each clamp bucket enforces a different utilization
clamp value.
Clamp values are always MAX aggregated for both util_min and util_max.
This ensures that no task can affect the performance of other
co-scheduled tasks which are more boosted (i.e. with higher util_min
clamp) or less capped (i.e. with higher util_max clamp).
A task has:
task_struct::uclamp[clamp_id]::bucket_id
to track the "bucket index" of the CPU's clamp bucket it refcounts while
enqueued, for each clamp index (clamp_id).
A runqueue has:
rq::uclamp[clamp_id]::bucket[bucket_id].tasks
to track how many RUNNABLE tasks on that CPU refcount each
clamp bucket (bucket_id) of a clamp index (clamp_id).
It also has a:
rq::uclamp[clamp_id]::bucket[bucket_id].value
to track the clamp value of each clamp bucket (bucket_id) of a clamp
index (clamp_id).
The rq::uclamp::bucket[clamp_id][] array is scanned every time it's
needed to find a new MAX aggregated clamp value for a clamp_id. This
operation is required only when it's dequeued the last task of a clamp
bucket tracking the current MAX aggregated clamp value. In this case,
the CPU is either entering IDLE or going to schedule a less boosted or
more clamped task.
The expected number of different clamp values configured at build time
is small enough to fit the full unordered array into a single cache
line, for configurations of up to 7 buckets.
Add to struct rq the basic data structures required to refcount the
number of RUNNABLE tasks for each clamp bucket. Add also the max
aggregation required to update the rq's clamp value at each
enqueue/dequeue event.
Use a simple linear mapping of clamp values into clamp buckets.
Pre-compute and cache bucket_id to avoid integer divisions at
enqueue/dequeue time.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The term 'weighted' is not needed since there is no 'unweighted' load.
Instead use the term 'runnable' to distinguish 'runnable' load
(avg.runnable_load_avg) used in load balance from load (avg.load_avg)
which is the sum of 'runnable' and 'blocked' load.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/57f27a7f-2775-d832-e965-0f4d51bb1954@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So that external modules can hook into them and extract the info they
need. Since these new tracepoints have no events associated with them
exporting these tracepoints make them useful for external modules to
perform testing and debugging. There's no other way otherwise to access
them.
BPF doesn't have infrastructure to access these bare tracepoints either.
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-7-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The new tracepoint allows us to track the changes in overutilized
status.
Overutilized status is associated with EAS. It indicates that the system
is in high performance state. EAS is disabled when the system is in this
state since there's not much energy savings while high performance tasks
are pushing the system to the limit and it's better to default to the
spreading behavior of the scheduler.
This tracepoint helps understanding and debugging the conditions under
which this happens.
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-6-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The new functions allow modules to access internal data structures of
unexported struct cfs_rq and struct rq to extract important information
from the tracepoints to be introduced in later patches.
While at it fix alphabetical order of struct declarations in sched.h
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-3-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Remove the #ifdef CONFIG_SCHED_DEBUG.
Some of the tracepoints to be introduced in later patches need to access
this function. Hence make it always available since the tracepoints are
not protected by CONFIG_SCHED_DEBUG.
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-2-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Statements in the loop's body and before it are identical.
Use do-while to not repeat it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/43ffea6ee2152b90dedf962eac851609e4197218.1560256112.git.asml.silence@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Nadav reported that code-gen changed because of the this_cpu_*()
constraints, avoid this for select_idle_cpu() because that runs with
preemption (and IRQs) disabled anyway.
Reported-by: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a cfs_rq sleeps and returns its quota, we delay for 5ms before
waking any throttled cfs_rqs to coalesce with other cfs_rqs going to
sleep, as this has to be done outside of the rq lock we hold.
The current code waits for 5ms without any sleeps, instead of waiting
for 5ms from the first sleep, which can delay the unthrottle more than
we want. Switch this around so that we can't push this forward forever.
This requires an extra flag rather than using hrtimer_active, since we
need to start a new timer if the current one is in the process of
finishing.
Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Xunlei Pang <xlpang@linux.alibaba.com>
Acked-by: Phil Auld <pauld@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/xm26a7euy6iq.fsf_-_@bsegall-linux.svl.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Jens reported that significant performance can be had on some block
workloads by special casing local wakeups. That is, wakeups on the
current task before it schedules out.
Given something like the normal wait pattern:
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (cond)
break;
schedule();
}
__set_current_state(TASK_RUNNING);
Any wakeup (on this CPU) after set_current_state() and before
schedule() would benefit from this.
Normal wakeups take p->pi_lock, which serializes wakeups to the same
task. By eliding that we gain concurrency on:
- ttwu_stat(); we already had concurrency on rq stats, this now also
brings it to task stats. -ENOCARE
- tracepoints; it is now possible to get multiple instances of
trace_sched_waking() (and possibly trace_sched_wakeup()) for the
same task. Tracers will have to learn to cope.
Furthermore, p->pi_lock is used by set_special_state(), to order
against TASK_RUNNING stores from other CPUs. But since this is
strictly CPU local, we don't need the lock, and set_special_state()'s
disabling of IRQs is sufficient.
After the normal wakeup takes p->pi_lock it issues
smp_mb__after_spinlock(), in order to ensure the woken task must
observe prior stores before we observe the p->state. If this is CPU
local, this will be satisfied with a compiler barrier, and we rely on
try_to_wake_up() being a funcation call, which implies such.
Since, when 'p == current', 'p->on_rq' must be true, the normal wakeup
would continue into the ttwu_remote() branch, which normally is
concerned with exactly this wakeup scenario, except from a remote CPU.
IOW we're waking a task that is still running. In this case, we can
trivially avoid taking rq->lock, all that's left from this is to set
p->state.
This then yields an extremely simple and fast path for 'p == current'.
Reported-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: gkohli@codeaurora.org
Cc: hch@lst.de
Cc: oleg@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
runnable_avg_yN_inv[] is only used in kernel/sched/pelt.c but was
included in several other places because they need other macros all
came from kernel/sched/sched-pelt.h which was generated by
Documentation/scheduler/sched-pelt. As the result, it causes compilation
a lot of warnings,
kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but not used [-Wunused-const-variable=]
kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but not used [-Wunused-const-variable=]
kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but not used [-Wunused-const-variable=]
...
Silence it by appending the __maybe_unused attribute for it, so all
generated variables and macros can still be kept in the same file.
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1559596304-31581-1-git-send-email-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
cfs_rq_has_blocked() and others_have_blocked() are only used within
update_blocked_averages(). The !CONFIG_FAIR_GROUP_SCHED version of the
latter calls them within a #define CONFIG_NO_HZ_COMMON block, whereas
the CONFIG_FAIR_GROUP_SCHED one calls them unconditionnally.
As reported by Qian, the above leads to this warning in
!CONFIG_NO_HZ_COMMON configs:
kernel/sched/fair.c: In function 'update_blocked_averages':
kernel/sched/fair.c:7750:7: warning: variable 'done' set but not used [-Wunused-but-set-variable]
It wouldn't be wrong to keep cfs_rq_has_blocked() and
others_have_blocked() as they are, but since their only current use is
to figure out when we can stop calling update_blocked_averages() on
fully decayed NOHZ idle CPUs, we can give them a new definition for
!CONFIG_NO_HZ_COMMON.
Change the definition of cfs_rq_has_blocked() and
others_have_blocked() for !CONFIG_NO_HZ_COMMON so that the
NOHZ-specific blocks of update_blocked_averages() become no-ops and
the 'done' variable gets optimised out.
While at it, remove the CONFIG_NO_HZ_COMMON block from the
!CONFIG_FAIR_GROUP_SCHED definition of update_blocked_averages() by
using the newly-introduced update_blocked_load_status() helper.
No change in functionality intended.
[ Additions by Peter Zijlstra. ]
Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190603115424.7951-1-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Non-inline io_schedule() was introduced in:
commit 10ab56434f ("sched/core: Separate out io_schedule_prepare() and io_schedule_finish()")
Keep in line with io_schedule_timeout(), otherwise "/proc/<pid>/wchan" will
report io_schedule() rather than its callers when waiting for IO.
Reported-by: Jilong Kou <koujilong@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miao Xie <miaoxie@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 10ab56434f ("sched/core: Separate out io_schedule_prepare() and io_schedule_finish()")
Link: https://lkml.kernel.org/r/20190603091338.2695-1-gaoxiang25@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In order to prepare to add them to the Kernel API book,
convert the files to ReST format.
The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation version 2 of the license
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 315 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since sg_lb_stats::sum_weighted_load is now identical with
sg_lb_stats::group_load remove it and replace its use case
(calculating load per task) with the latter.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20190527062116.11512-7-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This reverts:
commit 201c373e8e ("sched/debug: Limit sd->*_idx range on sysctl")
Load indexes (sd->*_idx) are no longer needed without rq->cpu_load[].
The range check for load indexes can be removed as well. Get rid of it
before the rq->cpu_load[] since it uses CPU_LOAD_IDX_MAX.
At the same time, fix the following coding style issues detected by
scripts/checkpatch.pl:
ERROR: space prohibited before that ','
ERROR: space prohibited before that close parenthesis ')'
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190527062116.11512-4-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With LB_BIAS disabled, source_load() & target_load() return
weighted_cpuload(). Replace both with calls to weighted_cpuload().
The function to obtain the load index (sd->*_idx) for an sd,
get_sd_load_idx(), can be removed as well.
Finally, get rid of the sched feature LB_BIAS.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190527062116.11512-3-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With LB_BIAS disabled, there is no need to update the rq->cpu_load[idx]
any more.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190527062116.11512-2-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The CFS class is the only one maintaining and using the CPU wide load
(rq->load(.weight)). The last use case of the CPU wide load in CFS's
set_next_entity() can be replaced by using the load of the CFS class
(rq->cfs.load(.weight)) instead.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190424084556.604-1-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In commit:
4b53a3412d ("sched/core: Remove the tsk_nr_cpus_allowed() wrapper")
the tsk_nr_cpus_allowed() wrapper was removed. There was not
much difference in !RT but in RT we used this to implement
migrate_disable(). Within a migrate_disable() section the CPU mask is
restricted to single CPU while the "normal" CPU mask remains untouched.
As an alternative implementation Ingo suggested to use:
struct task_struct {
const cpumask_t *cpus_ptr;
cpumask_t cpus_mask;
};
with
t->cpus_ptr = &t->cpus_mask;
In -RT we then can switch the cpus_ptr to:
t->cpus_ptr = &cpumask_of(task_cpu(p));
in a migration disabled region. The rules are simple:
- Code that 'uses' ->cpus_allowed would use the pointer.
- Code that 'modifies' ->cpus_allowed would use the direct mask.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190423142636.14347-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Based on 3 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version [author] [kishon] [vijay] [abraham]
[i] [kishon]@[ti] [com] this program is distributed in the hope that
it will be useful but without any warranty without even the implied
warranty of merchantability or fitness for a particular purpose see
the gnu general public license for more details
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version [author] [graeme] [gregory]
[gg]@[slimlogic] [co] [uk] [author] [kishon] [vijay] [abraham] [i]
[kishon]@[ti] [com] [based] [on] [twl6030]_[usb] [c] [author] [hema]
[hk] [hemahk]@[ti] [com] this program is distributed in the hope
that it will be useful but without any warranty without even the
implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 1105 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.202006027@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add SPDX license identifiers to all files which:
- Have no license information of any form
- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pressure metrics are already recorded and exposed in procfs for the
entire system, but any tool which monitors cgroup pressure has to
special case the root cgroup to read from procfs. This patch exposes
the already recorded pressure metrics on the root cgroup.
Link: http://lkml.kernel.org/r/20190510174938.3361741-1-dschatzberg@fb.com
Signed-off-by: Dan Schatzberg <dschatzberg@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Psi monitor aims to provide a low-latency short-term pressure detection
mechanism configurable by users. It allows users to monitor psi metrics
growth and trigger events whenever a metric raises above user-defined
threshold within user-defined time window.
Time window and threshold are both expressed in usecs. Multiple psi
resources with different thresholds and window sizes can be monitored
concurrently.
Psi monitors activate when system enters stall state for the monitored
psi metric and deactivate upon exit from the stall state. While system
is in the stall state psi signal growth is monitored at a rate of 10
times per tracking window. Min window size is 500ms, therefore the min
monitoring interval is 50ms. Max window size is 10s with monitoring
interval of 1s.
When activated psi monitor stays active for at least the duration of one
tracking window to avoid repeated activations/deactivations when psi
signal is bouncing.
Notifications to the users are rate-limited to one per tracking window.
Link: http://lkml.kernel.org/r/20190319235619.260832-8-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce changed_states parameter into collect_percpu_times to track
the states changed since the last update.
This will be needed to detect whether polled states activated in the
monitor patch.
Link: http://lkml.kernel.org/r/20190319235619.260832-6-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rename psi_group structure member fields used for calculating psi totals
and averages for clear distinction between them and for trigger-related
fields that will be added by "psi: introduce psi monitor".
[surenb@google.com: v6]
Link: http://lkml.kernel.org/r/20190319235619.260832-4-surenb@google.com
Link: http://lkml.kernel.org/r/20190124211518.244221-5-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
psi_enable is not used outside of psi.c, make it static.
Link: http://lkml.kernel.org/r/20190319235619.260832-3-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "psi: pressure stall monitors", v6.
This is a respin of:
https://lwn.net/ml/linux-kernel/20190308184311.144521-1-surenb%40google.com/
Android is adopting psi to detect and remedy memory pressure that
results in stuttering and decreased responsiveness on mobile devices.
Psi gives us the stall information, but because we're dealing with
latencies in the millisecond range, periodically reading the pressure
files to detect stalls in a timely fashion is not feasible. Psi also
doesn't aggregate its averages at a high-enough frequency right now.
This patch series extends the psi interface such that users can
configure sensitive latency thresholds and use poll() and friends to be
notified when these are breached.
As high-frequency aggregation is costly, it implements an aggregation
method that is optimized for fast, short-interval averaging, and makes
the aggregation frequency adaptive, such that high-frequency updates
only happen while monitored stall events are actively occurring.
With these patches applied, Android can monitor for, and ward off,
mounting memory shortages before they cause problems for the user. For
example, using memory stall monitors in userspace low memory killer
daemon (lmkd) we can detect mounting pressure and kill less important
processes before device becomes visibly sluggish. In our memory stress
testing psi memory monitors produce roughly 10x less false positives
compared to vmpressure signals. Having ability to specify multiple
triggers for the same psi metric allows other parts of Android framework
to monitor memory state of the device and act accordingly.
The new interface is straight-forward. The user opens one of the
pressure files for writing and writes a trigger description into the
file descriptor that defines the stall state - some or full, and the
maximum stall time over a given window of time. E.g.:
/* Signal when stall time exceeds 100ms of a 1s window */
char trigger[] = "full 100000 1000000"
fd = open("/proc/pressure/memory")
write(fd, trigger, sizeof(trigger))
while (poll() >= 0) {
...
};
close(fd);
When the monitored stall state is entered, psi adapts its aggregation
frequency according to what the configured time window requires in order
to emit event signals in a timely fashion. Once the stalling subsides,
aggregation reverts back to normal.
The trigger is associated with the open file descriptor. To stop
monitoring, the user only needs to close the file descriptor and the
trigger is discarded.
Patches 1-6 prepare the psi code for polling support. Patch 7
implements the adaptive polling logic, the pressure growth detection
optimized for short intervals, and hooks up write() and poll() on the
pressure files.
The patches were developed in collaboration with Johannes Weiner.
This patch (of 7):
The psi monitoring patches will need to determine the same states as
record_times(). To avoid calculating them twice, maintain a state mask
that can be consulted cheaply. Do this in a separate patch to keep the
churn in the main feature patch at a minimum.
This adds 4-byte state_mask member into psi_group_cpu struct which
results in its first cacheline-aligned part becoming 52 bytes long. Add
explicit values to enumeration element counters that affect
psi_group_cpu struct size.
Link: http://lkml.kernel.org/r/20190124211518.244221-4-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Here is the "big" set of driver core patches for 5.2-rc1
There are a number of ACPI patches in here as well, as Rafael said they
should go through this tree due to the driver core changes they
required. They have all been acked by the ACPI developers.
There are also a number of small subsystem-specific changes in here, due
to some changes to the kobject core code. Those too have all been acked
by the various subsystem maintainers.
As for content, it's pretty boring outside of the ACPI changes:
- spdx cleanups
- kobject documentation updates
- default attribute groups for kobjects
- other minor kobject/driver core fixes
All have been in linux-next for a while with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-----BEGIN PGP SIGNATURE-----
iG0EABECAC0WIQT0tgzFv3jCIUoxPcsxR9QN2y37KQUCXNHDbw8cZ3JlZ0Brcm9h
aC5jb20ACgkQMUfUDdst+ynDAgCfbb4LBR6I50wFXb8JM/R6cAS7qrsAn1unshKV
8XCYcif2RxjtdJWXbjdm
=/rLh
-----END PGP SIGNATURE-----
Merge tag 'driver-core-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core/kobject updates from Greg KH:
"Here is the "big" set of driver core patches for 5.2-rc1
There are a number of ACPI patches in here as well, as Rafael said
they should go through this tree due to the driver core changes they
required. They have all been acked by the ACPI developers.
There are also a number of small subsystem-specific changes in here,
due to some changes to the kobject core code. Those too have all been
acked by the various subsystem maintainers.
As for content, it's pretty boring outside of the ACPI changes:
- spdx cleanups
- kobject documentation updates
- default attribute groups for kobjects
- other minor kobject/driver core fixes
All have been in linux-next for a while with no reported issues"
* tag 'driver-core-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (47 commits)
kobject: clean up the kobject add documentation a bit more
kobject: Fix kernel-doc comment first line
kobject: Remove docstring reference to kset
firmware_loader: Fix a typo ("syfs" -> "sysfs")
kobject: fix dereference before null check on kobj
Revert "driver core: platform: Fix the usage of platform device name(pdev->name)"
init/config: Do not select BUILD_BIN2C for IKCONFIG
Provide in-kernel headers to make extending kernel easier
kobject: Improve doc clarity kobject_init_and_add()
kobject: Improve docs for kobject_add/del
driver core: platform: Fix the usage of platform device name(pdev->name)
livepatch: Replace klp_ktype_patch's default_attrs with groups
cpufreq: schedutil: Replace default_attrs field with groups
padata: Replace padata_attr_type default_attrs field with groups
irqdesc: Replace irq_kobj_type's default_attrs field with groups
net-sysfs: Replace ktype default_attrs field with groups
block: Replace all ktype default_attrs with groups
samples/kobject: Replace foo_ktype's default_attrs field with groups
kobject: Add support for default attribute groups to kobj_type
driver core: Postpone DMA tear-down until after devres release for probe failure
...
- Fix the handling of Performance and Energy Bias Hint (EPB) on
Intel processors and expose it to user space via sysfs to avoid
having to access it through the generic MSR I/F (Rafael Wysocki).
- Improve the handling of global turbo changes made by the platform
firmware in the intel_pstate driver (Rafael Wysocki).
- Convert some slow-path static_cpu_has() callers to boot_cpu_has()
in cpufreq (Borislav Petkov).
- Fix the frequency calculation loop in the armada-37xx cpufreq
driver (Gregory CLEMENT).
- Fix possible object reference leaks in multuple cpufreq drivers
(Wen Yang).
- Fix kerneldoc comment in the centrino cpufreq driver (dongjian).
- Clean up the ACPI and maple cpufreq drivers (Viresh Kumar, Mohan
Kumar).
- Add support for lx2160a and ls1028a to the qoriq cpufreq driver
(Vabhav Sharma, Yuantian Tang).
- Fix kobject memory leak in the cpufreq core (Viresh Kumar).
- Simplify the IOwait boosting in the schedutil cpufreq governor
and rework the TSC cpufreq notifier on x86 (Rafael Wysocki).
- Clean up the cpufreq core and statistics code (Yue Hu, Kyle Lin).
- Improve the cpufreq documentation, add SPDX license tags to
some PM documentation files and unify copyright notices in
them (Rafael Wysocki).
- Add support for "CPU" domains to the generic power domains (genpd)
framework and provide low-level PSCI firmware support for that
feature (Ulf Hansson).
- Rearrange the PSCI firmware support code and add support for
SYSTEM_RESET2 to it (Ulf Hansson, Sudeep Holla).
- Improve genpd support for devices in multiple power domains (Ulf
Hansson).
- Unify target residency for the AFTR and coupled AFTR states in the
exynos cpuidle driver (Marek Szyprowski).
- Introduce new helper routine in the operating performance points
(OPP) framework (Andrew-sh.Cheng).
- Add support for passing on-die termination (ODT) and auto power
down parameters from the kernel to Trusted Firmware-A (TF-A) to
the rk3399_dmc devfreq driver (Enric Balletbo i Serra).
- Add tracing to devfreq (Lukasz Luba).
- Make the exynos-bus devfreq driver suspend all devices on system
shutdown (Marek Szyprowski).
- Fix a few minor issues in the devfreq subsystem and clean it up
somewhat (Enric Balletbo i Serra, MyungJoo Ham, Rob Herring,
Saravana Kannan, Yangtao Li).
- Improve system wakeup diagnostics (Stephen Boyd).
- Rework filesystem sync messages emitted during system suspend and
hibernation (Harry Pan).
-----BEGIN PGP SIGNATURE-----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=nY9p
-----END PGP SIGNATURE-----
Merge tag 'pm-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"These fix the (Intel-specific) Performance and Energy Bias Hint (EPB)
handling and expose it to user space via sysfs, fix and clean up
several cpufreq drivers, add support for two new chips to the qoriq
cpufreq driver, fix, simplify and clean up the cpufreq core and the
schedutil governor, add support for "CPU" domains to the generic power
domains (genpd) framework and provide low-level PSCI firmware support
for that feature, fix the exynos cpuidle driver and fix a couple of
issues in the devfreq subsystem and clean it up.
Specifics:
- Fix the handling of Performance and Energy Bias Hint (EPB) on Intel
processors and expose it to user space via sysfs to avoid having to
access it through the generic MSR I/F (Rafael Wysocki).
- Improve the handling of global turbo changes made by the platform
firmware in the intel_pstate driver (Rafael Wysocki).
- Convert some slow-path static_cpu_has() callers to boot_cpu_has()
in cpufreq (Borislav Petkov).
- Fix the frequency calculation loop in the armada-37xx cpufreq
driver (Gregory CLEMENT).
- Fix possible object reference leaks in multuple cpufreq drivers
(Wen Yang).
- Fix kerneldoc comment in the centrino cpufreq driver (dongjian).
- Clean up the ACPI and maple cpufreq drivers (Viresh Kumar, Mohan
Kumar).
- Add support for lx2160a and ls1028a to the qoriq cpufreq driver
(Vabhav Sharma, Yuantian Tang).
- Fix kobject memory leak in the cpufreq core (Viresh Kumar).
- Simplify the IOwait boosting in the schedutil cpufreq governor and
rework the TSC cpufreq notifier on x86 (Rafael Wysocki).
- Clean up the cpufreq core and statistics code (Yue Hu, Kyle Lin).
- Improve the cpufreq documentation, add SPDX license tags to some PM
documentation files and unify copyright notices in them (Rafael
Wysocki).
- Add support for "CPU" domains to the generic power domains (genpd)
framework and provide low-level PSCI firmware support for that
feature (Ulf Hansson).
- Rearrange the PSCI firmware support code and add support for
SYSTEM_RESET2 to it (Ulf Hansson, Sudeep Holla).
- Improve genpd support for devices in multiple power domains (Ulf
Hansson).
- Unify target residency for the AFTR and coupled AFTR states in the
exynos cpuidle driver (Marek Szyprowski).
- Introduce new helper routine in the operating performance points
(OPP) framework (Andrew-sh.Cheng).
- Add support for passing on-die termination (ODT) and auto power
down parameters from the kernel to Trusted Firmware-A (TF-A) to the
rk3399_dmc devfreq driver (Enric Balletbo i Serra).
- Add tracing to devfreq (Lukasz Luba).
- Make the exynos-bus devfreq driver suspend all devices on system
shutdown (Marek Szyprowski).
- Fix a few minor issues in the devfreq subsystem and clean it up
somewhat (Enric Balletbo i Serra, MyungJoo Ham, Rob Herring,
Saravana Kannan, Yangtao Li).
- Improve system wakeup diagnostics (Stephen Boyd).
- Rework filesystem sync messages emitted during system suspend and
hibernation (Harry Pan)"
* tag 'pm-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (72 commits)
cpufreq: Fix kobject memleak
cpufreq: armada-37xx: fix frequency calculation for opp
cpufreq: centrino: Fix centrino_setpolicy() kerneldoc comment
cpufreq: qoriq: add support for lx2160a
x86: tsc: Rework time_cpufreq_notifier()
PM / Domains: Allow to attach a CPU via genpd_dev_pm_attach_by_id|name()
PM / Domains: Search for the CPU device outside the genpd lock
PM / Domains: Drop unused in-parameter to some genpd functions
PM / Domains: Use the base device for driver_deferred_probe_check_state()
cpufreq: qoriq: Add ls1028a chip support
PM / Domains: Enable genpd_dev_pm_attach_by_id|name() for single PM domain
PM / Domains: Allow OF lookup for multi PM domain case from ->attach_dev()
PM / Domains: Don't kfree() the virtual device in the error path
cpufreq: Move ->get callback check outside of __cpufreq_get()
PM / Domains: remove unnecessary unlikely()
cpufreq: Remove needless bios_limit check in show_bios_limit()
drivers/cpufreq/acpi-cpufreq.c: This fixes the following checkpatch warning
firmware/psci: add support for SYSTEM_RESET2
PM / devfreq: add tracing for scheduling work
trace: events: add devfreq trace event file
...
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle were:
- Make nohz housekeeping processing more permissive and less
intrusive to isolated CPUs
- Decouple CPU-bound workqueue acconting from the scheduler and move
it into the workqueue code.
- Optimize topology building
- Better handle quota and period overflows
- Add more RCU annotations
- Comment updates, misc cleanups"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits)
nohz_full: Allow the boot CPU to be nohz_full
sched/isolation: Require a present CPU in housekeeping mask
kernel/cpu: Allow non-zero CPU to be primary for suspend / kexec freeze
power/suspend: Add function to disable secondaries for suspend
sched/core: Allow the remote scheduler tick to be started on CPU0
sched/nohz: Run NOHZ idle load balancer on HK_FLAG_MISC CPUs
sched/debug: Fix spelling mistake "logaritmic" -> "logarithmic"
sched/topology: Update init_sched_domains() comment
cgroup/cpuset: Update stale generate_sched_domains() comments
sched/core: Check quota and period overflow at usec to nsec conversion
sched/core: Handle overflow in cpu_shares_write_u64
sched/rt: Check integer overflow at usec to nsec conversion
sched/core: Fix typo in comment
sched/core: Make some functions static
sched/core: Unify p->on_rq updates
sched/core: Remove ttwu_activate()
sched/core, workqueues: Distangle worker accounting from rq lock
sched/fair: Remove unneeded prototype of capacity_of()
sched/topology: Skip duplicate group rewrites in build_sched_groups()
sched/topology: Fix build_sched_groups() comment
...
Pull unified TLB flushing from Ingo Molnar:
"This contains the generic mmu_gather feature from Peter Zijlstra,
which is an all-arch unification of TLB flushing APIs, via the
following (broad) steps:
- enhance the <asm-generic/tlb.h> APIs to cover more arch details
- convert most TLB flushing arch implementations to the generic
<asm-generic/tlb.h> APIs.
- remove leftovers of per arch implementations
After this series every single architecture makes use of the unified
TLB flushing APIs"
* 'core-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
mm/resource: Use resource_overlaps() to simplify region_intersects()
ia64/tlb: Eradicate tlb_migrate_finish() callback
asm-generic/tlb: Remove tlb_table_flush()
asm-generic/tlb: Remove tlb_flush_mmu_free()
asm-generic/tlb: Remove CONFIG_HAVE_GENERIC_MMU_GATHER
asm-generic/tlb: Remove arch_tlb*_mmu()
s390/tlb: Convert to generic mmu_gather
asm-generic/tlb: Introduce CONFIG_HAVE_MMU_GATHER_NO_GATHER=y
arch/tlb: Clean up simple architectures
um/tlb: Convert to generic mmu_gather
sh/tlb: Convert SH to generic mmu_gather
ia64/tlb: Convert to generic mmu_gather
arm/tlb: Convert to generic mmu_gather
asm-generic/tlb, arch: Invert CONFIG_HAVE_RCU_TABLE_INVALIDATE
asm-generic/tlb, ia64: Conditionally provide tlb_migrate_finish()
asm-generic/tlb: Provide generic tlb_flush() based on flush_tlb_mm()
asm-generic/tlb, arch: Provide generic tlb_flush() based on flush_tlb_range()
asm-generic/tlb, arch: Provide generic VIPT cache flush
asm-generic/tlb, arch: Provide CONFIG_HAVE_MMU_GATHER_PAGE_SIZE
asm-generic/tlb: Provide a comment
During housekeeping mask setup, currently a possible CPU is required.
That does not guarantee the CPU would be available at boot time, so
check to ensure that at least one present CPU is in the mask.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lkml.kernel.org/r/20190411033448.20842-5-npiggin@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This has no effect yet because CPU0 will always be a housekeeping CPU
until a later change.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lkml.kernel.org/r/20190411033448.20842-2-npiggin@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently the error return path from kobject_init_and_add() is not
followed by a call to kobject_put() - which means we are leaking
the kobject.
Fix it by adding a call to kobject_put() in the error path of
kobject_init_and_add().
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tobin C. Harding <tobin@kernel.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20190430001144.24890-1-tobin@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The NOHZ idle balancer runs on the lowest idle CPU. This can
interfere with isolated CPUs, so confine it to HK_FLAG_MISC
housekeeping CPUs.
HK_FLAG_SCHED is not used for this because it is not set anywhere
at the moment. This could be folded into HK_FLAG_SCHED once that
option is fixed.
The problem was observed with increased jitter on an application
running on CPU0, caused by NOHZ idle load balancing being run on
CPU1 (an SMT sibling).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190412042613.28930-1-npiggin@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The kobj_type default_attrs field is being replaced by the
default_groups field. Replace sugov_tunables_ktype's default_attrs field
with default groups. Change "sugov_attributes" to "sugov_attrs" and use
the ATTRIBUTE_GROUPS macro to create sugov_groups.
This patch was tested by setting the scaling governor to schedutil and
verifying that the sysfs files for the attributes in the default groups
were created.
Signed-off-by: Kimberly Brown <kimbrownkd@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sched_clock_cpu() may not be consistent between CPUs. If a task
migrates to another CPU, then se.exec_start is set to that CPU's
rq_clock_task() by update_stats_curr_start(). Specifically, the new
value might be before the old value due to clock skew.
So then if in numa_get_avg_runtime() the expression:
'now - p->last_task_numa_placement'
ends up as -1, then the divider '*period + 1' in task_numa_placement()
is 0 and things go bang. Similar to update_curr(), check if time goes
backwards to avoid this.
[ peterz: Wrote new changelog. ]
[ mingo: Tweaked the code comment. ]
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: cj.chengjian@huawei.com
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20190425080016.GX11158@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Large values could overflow u64 and pass following sanity checks.
# echo 18446744073750000 > cpu.cfs_period_us
# cat cpu.cfs_period_us
40448
# echo 18446744073750000 > cpu.cfs_quota_us
# cat cpu.cfs_quota_us
40448
After this patch they will fail with -EINVAL.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/155125502079.293431.3947497929372138600.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Bit shift in scale_load() could overflow shares. This patch saturates
it to MAX_SHARES like following sched_group_set_shares().
Example:
# echo 9223372036854776832 > cpu.shares
# cat cpu.shares
Before patch: 1024
After pattch: 262144
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/155125501891.293431.3345233332801109696.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix these sparse warnings:
kernel/sched/core.c:6577:11: warning: symbol 'min_cfs_quota_period' was not declared. Should it be static?
kernel/sched/core.c:6657:5: warning: symbol 'tg_set_cfs_quota' was not declared. Should it be static?
kernel/sched/core.c:6670:6: warning: symbol 'tg_get_cfs_quota' was not declared. Should it be static?
kernel/sched/core.c:6683:5: warning: symbol 'tg_set_cfs_period' was not declared. Should it be static?
kernel/sched/core.c:6693:6: warning: symbol 'tg_get_cfs_period' was not declared. Should it be static?
kernel/sched/fair.c:2596:6: warning: symbol 'task_tick_numa' was not declared. Should it be static?
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20190418144713.34332-1-yuehaibing@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Almost all {,de}activate_task() invocations pair with p->on_rq
updates, the exception being the usage in rt/deadline which hold both
rq locks and therefore don't strictly need to set
TASK_ON_RQ_MIGRATING, but it is harmless if we do anyway.
Put the updates in {,de}activate_task() and cut down on repetition.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After the removal of try_to_wake_up_local(), there is only one user of
ttwu_activate() left, and since it is a trivial function, remove it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The worker accounting for CPU bound workers is plugged into the core
scheduler code and the wakeup code. This is not a hard requirement and
can be avoided by keeping track of the state in the workqueue code
itself.
Keep track of the sleeping state in the worker itself and call the
notifier before entering the core scheduler. There might be false
positives when the task is woken between that call and actually
scheduling, but that's not really different from scheduling and being
woken immediately after switching away. When nr_running is updated when
the task is retunrning from schedule() then it is later compared when it
is done from ttwu().
[ bigeasy: preempt_disable() around wq_worker_sleeping() by Daniel Bristot de Oliveira ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/ad2b29b5715f970bffc1a7026cabd6ff0b24076a.1532952814.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
syzbot reported the following warning:
[ ] WARNING: CPU: 4 PID: 17089 at kernel/sched/deadline.c:255 task_non_contending+0xae0/0x1950
line 255 of deadline.c is:
WARN_ON(hrtimer_active(&dl_se->inactive_timer));
in task_non_contending().
Unfortunately, in some cases (for example, a deadline task
continuosly blocking and waking immediately) it can happen that
a task blocks (and task_non_contending() is called) while the
0-lag timer is still active.
In this case, the safest thing to do is to immediately decrease
the running bandwidth of the task, without trying to re-arm the 0-lag timer.
Signed-off-by: luca abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: chengjian (D) <cj.chengjian@huawei.com>
Link: https://lkml.kernel.org/r/20190325131530.34706-1-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With extremely short cfs_period_us setting on a parent task group with a large
number of children the for loop in sched_cfs_period_timer() can run until the
watchdog fires. There is no guarantee that the call to hrtimer_forward_now()
will ever return 0. The large number of children can make
do_sched_cfs_period_timer() take longer than the period.
NMI watchdog: Watchdog detected hard LOCKUP on cpu 24
RIP: 0010:tg_nop+0x0/0x10
<IRQ>
walk_tg_tree_from+0x29/0xb0
unthrottle_cfs_rq+0xe0/0x1a0
distribute_cfs_runtime+0xd3/0xf0
sched_cfs_period_timer+0xcb/0x160
? sched_cfs_slack_timer+0xd0/0xd0
__hrtimer_run_queues+0xfb/0x270
hrtimer_interrupt+0x122/0x270
smp_apic_timer_interrupt+0x6a/0x140
apic_timer_interrupt+0xf/0x20
</IRQ>
To prevent this we add protection to the loop that detects when the loop has run
too many times and scales the period and quota up, proportionally, so that the timer
can complete before then next period expires. This preserves the relative runtime
quota while preventing the hard lockup.
A warning is issued reporting this state and the new values.
Signed-off-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190319130005.25492-1-pauld@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The prototype of that function was already hoisted up in:
commit 3b1baa6496 ("sched/fair: Add 'group_misfit_task' load-balance type")
but that seems to have been missed. Get rid of the extra prototype.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Acked-by: Quentin Perret <quentin.perret@arm.com>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Fixes: 2802bf3cd9 ("sched/fair: Add over-utilization/tipping point indicator")
Link: http://lkml.kernel.org/r/20190416140621.19884-1-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While staring at build_sched_domains(), I realized that get_group()
does several duplicate (thus useless) writes.
If you take the Arm Juno r0 (LITTLEs = [0, 3, 4, 5], bigs = [1, 2]), the
sched_group build flow would look like this:
('MC[cpu]->sg' means 'per_cpu_ptr(&tl->data->sg, cpu)' with 'tl == MC')
build_sched_groups(MC[CPU0]->sd, CPU0)
get_group(0) -> MC[CPU0]->sg
get_group(3) -> MC[CPU3]->sg
get_group(4) -> MC[CPU4]->sg
get_group(5) -> MC[CPU5]->sg
build_sched_groups(DIE[CPU0]->sd, CPU0)
get_group(0) -> DIE[CPU0]->sg
get_group(1) -> DIE[CPU1]->sg <=================+
|
build_sched_groups(MC[CPU1]->sd, CPU1) |
get_group(1) -> MC[CPU1]->sg |
get_group(2) -> MC[CPU2]->sg |
|
build_sched_groups(DIE[CPU1]->sd, CPU1) ^
get_group(1) -> DIE[CPU1]->sg } We've set up these two up here!
get_group(3) -> DIE[CPU0]->sg }
From this point on, we will only use sched_groups that have been
previously visited & initialized. The only new operation will
be which group pointer we affect to sd->groups.
On the Juno r0 we get 32 get_group() calls, every single one of them
writing to a sched_group->cpumask. However, all of the data structures
we need are set up after 8 visits (see above).
Return early from get_group() if we've already visited (and thus
initialized) the sched_group we're looking at. Overlapping domains
are not affected as they do not use build_sched_groups().
Tested on a Juno and a 2 * (Xeon E5-2690) system.
( FWIW I initially checked the refs for both sg && sg->sgc, but figured if
they weren't both 0 or > 1 then something must have gone wrong, so I
threw in a WARN_ON(). )
No change in functionality intended.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The comment was introduced (pre 2.6.12) by:
8a7a2318dc07 ("[PATCH] sched: consolidate sched domains")
and referred to sched_group->cpu_power. This was folded into
sched_group->sched_group_power in
commit 9c3f75cbd1 ("sched: Break out cpu_power from the sched_group structure")
The comment was then updated in:
ced549fa5f ("sched: Remove remaining dubious usage of "power"")
but should have replaced "sg->cpu_capacity" with
"sg->sched_group_capacity". Do that now.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: qais.yousef@arm.com
Link: http://lkml.kernel.org/r/20190409173546.4747-3-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is not reason for the minimum iowait boost value in the
schedutil cpufreq governor to depend on the available range of CPU
frequencies. In fact, that dependency is generally confusing,
because it causes the iowait boost to behave somewhat differently
on CPUs with the same maximum frequency and different minimum
frequencies, for example.
For this reason, replace the min field in struct sugov_cpu
with a constant and choose its values to be 1/8 of
SCHED_CAPACITY_SCALE (for consistency with the intel_pstate
driver's internal governor).
[Note that policy->cpuinfo.max_freq will not be a constant any more
after a subsequent change, so this change is depended on by it.]
Link: https://lore.kernel.org/lkml/20190305083202.GU32494@hirez.programming.kicks-ass.net/T/#ee20bdc98b7d89f6110c0d00e5c3ee8c2ced93c3d
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Fix these sparse warnigs:
kernel/sched/fair.c:3570:6: warning: symbol 'sync_entity_load_avg' was not declared. Should it be static?
kernel/sched/fair.c:3583:6: warning: symbol 'remove_entity_load_avg' was not declared. Should it be static?
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190320133839.21392-1-yuehaibing@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This fixes the following sparse errors in sched/fair.c:
fair.c:6506:14: error: incompatible types in comparison expression
fair.c:8642:21: error: incompatible types in comparison expression
Using __rcu will also help sparse catch any future bugs.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ From an RCU perspective. ]
Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Cc: kernel-hardening@lists.openwall.com
Cc: kernel-team@android.com
Link: https://lkml.kernel.org/r/20190321003426.160260-5-joel@joelfernandes.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Recently I added an RCU annotation check to rcu_assign_pointer(). All
pointers assigned to RCU protected data are to be annotated with __rcu
inorder to be able to use rcu_assign_pointer() similar to checks in
other RCU APIs.
This resulted in a sparse error:
kernel//sched/cpufreq.c:41:9: sparse: error: incompatible types in comparison expression (different address spaces)
Fix this by annotating cpufreq_update_util_data pointer with __rcu. This
will also help sparse catch any future RCU misuage bugs.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
[ From an RCU perspective. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Cc: kernel-hardening@lists.openwall.com
Cc: kernel-team@android.com
Link: https://lkml.kernel.org/r/20190321003426.160260-2-joel@joelfernandes.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Only ia64-sn2 uses this as an optimization, and there it is of
questionable correctness due to the mm_users==1 test.
Remove it entirely.
No change in behavior intended.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A NULL pointer dereference bug was reported on a distribution kernel but
the same issue should be present on mainline kernel. It occured on s390
but should not be arch-specific. A partial oops looks like:
Unable to handle kernel pointer dereference in virtual kernel address space
...
Call Trace:
...
try_to_wake_up+0xfc/0x450
vhost_poll_wakeup+0x3a/0x50 [vhost]
__wake_up_common+0xbc/0x178
__wake_up_common_lock+0x9e/0x160
__wake_up_sync_key+0x4e/0x60
sock_def_readable+0x5e/0x98
The bug hits any time between 1 hour to 3 days. The dereference occurs
in update_cfs_rq_h_load when accumulating h_load. The problem is that
cfq_rq->h_load_next is not protected by any locking and can be updated
by parallel calls to task_h_load. Depending on the compiler, code may be
generated that re-reads cfq_rq->h_load_next after the check for NULL and
then oops when reading se->avg.load_avg. The dissassembly showed that it
was possible to reread h_load_next after the check for NULL.
While this does not appear to be an issue for later compilers, it's still
an accident if the correct code is generated. Full locking in this path
would have high overhead so this patch uses READ_ONCE to read h_load_next
only once and check for NULL before dereferencing. It was confirmed that
there were no further oops after 10 days of testing.
As Peter pointed out, it is also necessary to use WRITE_ONCE() to avoid any
potential problems with store tearing.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Fixes: 685207963b ("sched: Move h_load calculation to task_h_load()")
Link: https://lkml.kernel.org/r/20190319123610.nsivgf3mjbjjesxb@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler updates from Thomas Gleixner:
"Third more careful attempt for this set of fixes:
- Prevent a 32bit math overflow in the cpufreq code
- Fix a buffer overflow when scanning the cgroup2 cpu.max property
- A set of fixes for the NOHZ scheduler logic to prevent waking up
CPUs even if the capacity of the busy CPUs is sufficient along with
other tweaks optimizing the behaviour for asymmetric systems
(big/little)"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Skip LLC NOHZ logic for asymmetric systems
sched/fair: Tune down misfit NOHZ kicks
sched/fair: Comment some nohz_balancer_kick() kick conditions
sched/core: Fix buffer overflow in cgroup2 property cpu.max
sched/cpufreq: Fix 32-bit math overflow
The LLC NOHZ condition will become true as soon as >=2 CPUs in a
single LLC domain are busy. On big.LITTLE systems, this translates to
two or more CPUs of a "cluster" (big or LITTLE) being busy.
Issuing a NOHZ kick in these conditions isn't desired for asymmetric
systems, as if the busy CPUs can provide enough compute capacity to
the running tasks, then we can leave the NOHZ CPUs in peace.
Skip the LLC NOHZ condition for asymmetric systems, and rely on
nr_running & capacity checks to trigger NOHZ kicks when the system
actually needs them.
Suggested-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dietmar.Eggemann@arm.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190211175946.4961-4-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In this commit:
3b1baa6496 ("sched/fair: Add 'group_misfit_task' load-balance type")
we set rq->misfit_task_load whenever the current running task has a
utilization greater than 80% of rq->cpu_capacity. A non-zero value in
this field enables misfit load balancing.
However, if the task being looked at is already running on a CPU of
highest capacity, there's nothing more we can do for it. We can
currently spot this in update_sd_pick_busiest(), which prevents us
from selecting a sched_group of group_type == group_misfit_task as the
busiest group, but we don't do any of that in nohz_balancer_kick().
This means that we could repeatedly kick NOHZ CPUs when there's no
improvements in terms of load balance to be done.
Introduce a check_misfit_status() helper that returns true iff there
is a CPU in the system that could give more CPU capacity to a rq's
misfit task - IOW, there exists a CPU of higher capacity_orig or the
rq's CPU is severely pressured by rt/IRQ.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dietmar.Eggemann@arm.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190211175946.4961-3-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We now have a comment explaining the first sched_domain based NOHZ kick,
so might as well comment them all.
While at it, unwrap a line that fits under 80 characters.
Co-authored-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dietmar.Eggemann@arm.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190211175946.4961-2-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Vincent Wang reported that get_next_freq() has a mult overflow bug on
32-bit platforms in the IOWAIT boost case, since in that case {util,max}
are in freq units instead of capacity units.
Solve this by moving the IOWAIT boost to capacity units. And since this
means @max is constant; simplify the code.
Reported-by: Vincent Wang <vincent.wang@unisoc.com>
Tested-by: Vincent Wang <vincent.wang@unisoc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190305083202.GU32494@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge misc updates from Andrew Morton:
- a few misc things
- ocfs2 updates
- most of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (159 commits)
tools/testing/selftests/proc/proc-self-syscall.c: remove duplicate include
proc: more robust bulk read test
proc: test /proc/*/maps, smaps, smaps_rollup, statm
proc: use seq_puts() everywhere
proc: read kernel cpu stat pointer once
proc: remove unused argument in proc_pid_lookup()
fs/proc/thread_self.c: code cleanup for proc_setup_thread_self()
fs/proc/self.c: code cleanup for proc_setup_self()
proc: return exit code 4 for skipped tests
mm,mremap: bail out earlier in mremap_to under map pressure
mm/sparse: fix a bad comparison
mm/memory.c: do_fault: avoid usage of stale vm_area_struct
writeback: fix inode cgroup switching comment
mm/huge_memory.c: fix "orig_pud" set but not used
mm/hotplug: fix an imbalance with DEBUG_PAGEALLOC
mm/memcontrol.c: fix bad line in comment
mm/cma.c: cma_declare_contiguous: correct err handling
mm/page_ext.c: fix an imbalance with kmemleak
mm/compaction: pass pgdat to too_many_isolated() instead of zone
mm: remove zone_lru_lock() function, access ->lru_lock directly
...
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle were:
- refcount conversions
- Solve the rq->leaf_cfs_rq_list can of worms for real.
- improve power-aware scheduling
- add sysctl knob for Energy Aware Scheduling
- documentation updates
- misc other changes"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
kthread: Do not use TIMER_IRQSAFE
kthread: Convert worker lock to raw spinlock
sched/fair: Use non-atomic cpumask_{set,clear}_cpu()
sched/fair: Remove unused 'sd' parameter from select_idle_smt()
sched/wait: Use freezable_schedule() when possible
sched/fair: Prune, fix and simplify the nohz_balancer_kick() comment block
sched/fair: Explain LLC nohz kick condition
sched/fair: Simplify nohz_balancer_kick()
sched/topology: Fix percpu data types in struct sd_data & struct s_data
sched/fair: Simplify post_init_entity_util_avg() by calling it with a task_struct pointer argument
sched/fair: Fix O(nr_cgroups) in the load balancing path
sched/fair: Optimize update_blocked_averages()
sched/fair: Fix insertion in rq->leaf_cfs_rq_list
sched/fair: Add tmp_alone_branch assertion
sched/core: Use READ_ONCE()/WRITE_ONCE() in move_queued_task()/task_rq_lock()
sched/debug: Initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK
sched/pelt: Skip updating util_est when utilization is higher than CPU's capacity
sched/fair: Update scale invariance of PELT
sched/fair: Move the rq_of() helper function
sched/core: Convert task_struct.stack_refcount to refcount_t
...
Pull locking updates from Ingo Molnar:
"The biggest part of this tree is the new auto-generated atomics API
wrappers by Mark Rutland.
The primary motivation was to allow instrumentation without uglifying
the primary source code.
The linecount increase comes from adding the auto-generated files to
the Git space as well:
include/asm-generic/atomic-instrumented.h | 1689 ++++++++++++++++--
include/asm-generic/atomic-long.h | 1174 ++++++++++---
include/linux/atomic-fallback.h | 2295 +++++++++++++++++++++++++
include/linux/atomic.h | 1241 +------------
I preferred this approach, so that the full call stack of the (already
complex) locking APIs is still fully visible in 'git grep'.
But if this is excessive we could certainly hide them.
There's a separate build-time mechanism to determine whether the
headers are out of date (they should never be stale if we do our job
right).
Anyway, nothing from this should be visible to regular kernel
developers.
Other changes:
- Add support for dynamic keys, which removes a source of false
positives in the workqueue code, among other things (Bart Van
Assche)
- Updates to tools/memory-model (Andrea Parri, Paul E. McKenney)
- qspinlock, wake_q and lockdep micro-optimizations (Waiman Long)
- misc other updates and enhancements"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (48 commits)
locking/lockdep: Shrink struct lock_class_key
locking/lockdep: Add module_param to enable consistency checks
lockdep/lib/tests: Test dynamic key registration
lockdep/lib/tests: Fix run_tests.sh
kernel/workqueue: Use dynamic lockdep keys for workqueues
locking/lockdep: Add support for dynamic keys
locking/lockdep: Verify whether lock objects are small enough to be used as class keys
locking/lockdep: Check data structure consistency
locking/lockdep: Reuse lock chains that have been freed
locking/lockdep: Fix a comment in add_chain_cache()
locking/lockdep: Introduce lockdep_next_lockchain() and lock_chain_count()
locking/lockdep: Reuse list entries that are no longer in use
locking/lockdep: Free lock classes that are no longer in use
locking/lockdep: Update two outdated comments
locking/lockdep: Make it easy to detect whether or not inside a selftest
locking/lockdep: Split lockdep_free_key_range() and lockdep_reset_lock()
locking/lockdep: Initialize the locks_before and locks_after lists earlier
locking/lockdep: Make zap_class() remove all matching lock order entries
locking/lockdep: Reorder struct lock_class members
locking/lockdep: Avoid that add_chain_cache() adds an invalid chain to the cache
...
Compaction is inherently race-prone as a suitable page freed during
compaction can be allocated by any parallel task. This patch uses a
capture_control structure to isolate a page immediately when it is freed
by a direct compactor in the slow path of the page allocator. The
intent is to avoid redundant scanning.
5.0.0-rc1 5.0.0-rc1
selective-v3r17 capture-v3r19
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 2582.11 ( 0.00%) 2563.68 ( 0.71%)
Amean fault-both-5 4500.26 ( 0.00%) 4233.52 ( 5.93%)
Amean fault-both-7 5819.53 ( 0.00%) 6333.65 ( -8.83%)
Amean fault-both-12 9321.18 ( 0.00%) 9759.38 ( -4.70%)
Amean fault-both-18 9782.76 ( 0.00%) 10338.76 ( -5.68%)
Amean fault-both-24 15272.81 ( 0.00%) 13379.55 * 12.40%*
Amean fault-both-30 15121.34 ( 0.00%) 16158.25 ( -6.86%)
Amean fault-both-32 18466.67 ( 0.00%) 18971.21 ( -2.73%)
Latency is only moderately affected but the devil is in the details. A
closer examination indicates that base page fault latency is reduced but
latency of huge pages is increased as it takes creater care to succeed.
Part of the "problem" is that allocation success rates are close to 100%
even when under pressure and compaction gets harder
5.0.0-rc1 5.0.0-rc1
selective-v3r17 capture-v3r19
Percentage huge-3 96.70 ( 0.00%) 98.23 ( 1.58%)
Percentage huge-5 96.99 ( 0.00%) 95.30 ( -1.75%)
Percentage huge-7 94.19 ( 0.00%) 97.24 ( 3.24%)
Percentage huge-12 94.95 ( 0.00%) 97.35 ( 2.53%)
Percentage huge-18 96.74 ( 0.00%) 97.30 ( 0.58%)
Percentage huge-24 97.07 ( 0.00%) 97.55 ( 0.50%)
Percentage huge-30 95.69 ( 0.00%) 98.50 ( 2.95%)
Percentage huge-32 96.70 ( 0.00%) 99.27 ( 2.65%)
And scan rates are reduced as expected by 6% for the migration scanner
and 29% for the free scanner indicating that there is less redundant
work.
Compaction migrate scanned 20815362 19573286
Compaction free scanned 16352612 11510663
[mgorman@techsingularity.net: remove redundant check]
Link: http://lkml.kernel.org/r/20190201143853.GH9565@techsingularity.net
Link: http://lkml.kernel.org/r/20190118175136.31341-23-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Replace all open encodings for NUMA_NO_NODE", v3.
All these places for replacement were found by running the following
grep patterns on the entire kernel code. Please let me know if this
might have missed some instances. This might also have replaced some
false positives. I will appreciate suggestions, inputs and review.
1. git grep "nid == -1"
2. git grep "node == -1"
3. git grep "nid = -1"
4. git grep "node = -1"
This patch (of 2):
At present there are multiple places where invalid node number is
encoded as -1. Even though implicitly understood it is always better to
have macros in there. Replace these open encodings for an invalid node
number with the global macro NUMA_NO_NODE. This helps remove NUMA
related assumptions like 'invalid node' from various places redirecting
them to a common definition.
Link: http://lkml.kernel.org/r/1545127933-10711-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> [ixgbe]
Acked-by: Jens Axboe <axboe@kernel.dk> [mtip32xx]
Acked-by: Vinod Koul <vkoul@kernel.org> [dmaengine.c]
Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc]
Acked-by: Doug Ledford <dledford@redhat.com> [drivers/infiniband]
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull year 2038 updates from Thomas Gleixner:
"Another round of changes to make the kernel ready for 2038. After lots
of preparatory work this is the first set of syscalls which are 2038
safe:
403 clock_gettime64
404 clock_settime64
405 clock_adjtime64
406 clock_getres_time64
407 clock_nanosleep_time64
408 timer_gettime64
409 timer_settime64
410 timerfd_gettime64
411 timerfd_settime64
412 utimensat_time64
413 pselect6_time64
414 ppoll_time64
416 io_pgetevents_time64
417 recvmmsg_time64
418 mq_timedsend_time64
419 mq_timedreceiv_time64
420 semtimedop_time64
421 rt_sigtimedwait_time64
422 futex_time64
423 sched_rr_get_interval_time64
The syscall numbers are identical all over the architectures"
* 'timers-2038-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
riscv: Use latest system call ABI
checksyscalls: fix up mq_timedreceive and stat exceptions
unicore32: Fix __ARCH_WANT_STAT64 definition
asm-generic: Make time32 syscall numbers optional
asm-generic: Drop getrlimit and setrlimit syscalls from default list
32-bit userspace ABI: introduce ARCH_32BIT_OFF_T config option
compat ABI: use non-compat openat and open_by_handle_at variants
y2038: add 64-bit time_t syscalls to all 32-bit architectures
y2038: rename old time and utime syscalls
y2038: remove struct definition redirects
y2038: use time32 syscall names on 32-bit
syscalls: remove obsolete __IGNORE_ macros
y2038: syscalls: rename y2038 compat syscalls
x86/x32: use time64 versions of sigtimedwait and recvmmsg
timex: change syscalls to use struct __kernel_timex
timex: use __kernel_timex internally
sparc64: add custom adjtimex/clock_adjtime functions
time: fix sys_timer_settime prototype
time: Add struct __kernel_timex
time: make adjtime compat handling available for 32 bit
...
Daniel Borkmann says:
====================
pull-request: bpf-next 2019-03-04
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Add AF_XDP support to libbpf. Rationale is to facilitate writing
AF_XDP applications by offering higher-level APIs that hide many
of the details of the AF_XDP uapi. Sample programs are converted
over to this new interface as well, from Magnus.
2) Introduce a new cant_sleep() macro for annotation of functions
that cannot sleep and use it in BPF_PROG_RUN() to assert that
BPF programs run under preemption disabled context, from Peter.
3) Introduce per BPF prog stats in order to monitor the usage
of BPF; this is controlled by kernel.bpf_stats_enabled sysctl
knob where monitoring tools can make use of this to efficiently
determine the average cost of programs, from Alexei.
4) Split up BPF selftest's test_progs similarly as we already
did with test_verifier. This allows to further reduce merge
conflicts in future and to get more structure into our
quickly growing BPF selftest suite, from Stanislav.
5) Fix a bug in BTF's dedup algorithm which can cause an infinite
loop in some circumstances; also various BPF doc fixes and
improvements, from Andrii.
6) Various BPF sample cleanups and migration to libbpf in order
to further isolate the old sample loader code (so we can get
rid of it at some point), from Jakub.
7) Add a new BPF helper for BPF cgroup skb progs that allows
to set ECN CE code point and a Host Bandwidth Manager (HBM)
sample program for limiting the bandwidth used by v2 cgroups,
from Lawrence.
8) Enable write access to skb->queue_mapping from tc BPF egress
programs in order to let BPF pick TX queue, from Jesper.
9) Fix a bug in BPF spinlock handling for map-in-map which did
not propagate spin_lock_off to the meta map, from Yonghong.
10) Fix a bug in the new per-CPU BPF prog counters to properly
initialize stats for each CPU, from Eric.
11) Add various BPF helper prototypes to selftest's bpf_helpers.h,
from Willem.
12) Fix various BPF samples bugs in XDP and tracing progs,
from Toke, Daniel and Yonghong.
13) Silence preemption splat in test_bpf after BPF_PROG_RUN()
enforces it now everywhere, from Anders.
14) Fix a signedness bug in libbpf's btf_dedup_ref_type() to
get error handling working, from Dan.
15) Fix bpftool documentation and auto-completion with regards
to stream_{verdict,parser} attach types, from Alban.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
We've been seeing hard-to-trigger psi crashes when running inside VM
instances:
divide error: 0000 [#1] SMP PTI
Modules linked in: [...]
CPU: 0 PID: 212 Comm: kworker/0:2 Not tainted 4.16.18-119_fbk9_3817_gfe944c98d695 #119
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
Workqueue: events psi_clock
RIP: 0010:psi_update_stats+0x270/0x490
RSP: 0018:ffffc90001117e10 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8800a35a13f8
RDX: 0000000000000000 RSI: ffff8800a35a1340 RDI: 0000000000000000
RBP: 0000000000000658 R08: ffff8800a35a1470 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00000000000f8502
FS: 0000000000000000(0000) GS:ffff88023fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbe370fa000 CR3: 00000000b1e3a000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
psi_clock+0x12/0x50
process_one_work+0x1e0/0x390
worker_thread+0x2b/0x3c0
? rescuer_thread+0x330/0x330
kthread+0x113/0x130
? kthread_create_worker_on_cpu+0x40/0x40
? SyS_exit_group+0x10/0x10
ret_from_fork+0x35/0x40
Code: 48 0f 47 c7 48 01 c2 45 85 e4 48 89 16 0f 85 e6 00 00 00 4c 8b 49 10 4c 8b 51 08 49 69 d9 f2 07 00 00 48 6b c0 64 4c 8b 29 31 d2 <48> f7 f7 49 69 d5 8d 06 00 00 48 89 c5 4c 69 f0 00 98 0b 00 48
The Code-line points to `period` being 0 inside update_stats(), and we
divide by that when calculating that period's pressure percentage.
The elapsed period should never be 0. The reason this can happen is due
to an off-by-one in the idle time / missing period calculation combined
with a coarse sched_clock() in the virtual machine.
The target time for aggregation is advanced into the future on a fixed
grid to prevent clock drift. So when an aggregation runs after some idle
period, we can not just set it to "now + psi_period", but have to
calculate the downtime and advance the target time relative to itself.
However, if the aggregator was disabled exactly one psi_period (ns), we
drop one idle period in the calculation due to a > when we should do >=.
In that case, next_update will be advanced from 'now - psi_period' to
'now' when it should be moved to 'now + psi_period'. The run finishes
with last_update == next_update == sched_clock().
With hardware clocks, this exact nanosecond match isn't likely in the
first place; but if it does happen, the clock will still have moved on and
the period non-zero by the time the worker runs. A pointlessly short
period, but besides the extra work, no harm no foul. However, a slow
sched_clock() like we have on VMs might not have advanced either by the
time the worker runs again. And when we calculate the elapsed period, the
result, our pressure divisor, will be 0. Ouch.
Fix this by correctly handling the situation when the elapsed time between
aggregation runs is precisely two periods, and advance the expiration
timestamp correctly to period into the future.
Link: http://lkml.kernel.org/r/20190214193157.15788-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Łukasz Siudut <lsiudut@fb.com
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce cant_sleep() macro for annotation of functions that
cannot sleep.
Use it in BPF_PROG_RUN to catch execution of BPF programs in
preemptable context.
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Pull the latest RCU tree from Paul E. McKenney:
- Additional cleanups after RCU flavor consolidation
- Grace-period forward-progress cleanups and improvements
- Documentation updates
- Miscellaneous fixes
- spin_is_locked() conversions to lockdep
- SPDX changes to RCU source and header files
- SRCU updates
- Torture-test updates, including nolibc updates and moving
nolibc to tools/include
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The cpumasks updated here are not subject to concurrency and using
atomic bitops for them is pointless and expensive. Use the non-atomic
variants instead.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/2e2a10f84b9049a81eef94ed6d5989447c21e34a.1549963617.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The 'sd' parameter isn't getting used in select_idle_smt(), drop it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/f91c5e118183e79d4a982e9ac4ce5e47948f6c1b.1549536337.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The comment block for that function lists the heuristics for
triggering a nohz kick, but the most recent ones (blocked load
updates, misfit) aren't included, and some of them (LLC nohz logic,
asym packing) are no longer in sync with the code.
The conditions are either simple enough or properly commented, so get
rid of that list instead of letting it grow.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190117153411.2390-4-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Calling 'nohz_balance_exit_idle(rq)' will always clear 'rq->cpu' from
'nohz.idle_cpus_mask' if it is set. Since it is called at the top of
'nohz_balancer_kick()', 'rq->cpu' will never be set in
'nohz.idle_cpus_mask' if it is accessed in the rest of the function.
Combine the 'sched_domain_span()' with 'nohz.idle_cpus_mask' and drop the
'(i == cpu)' check since 'rq->cpu' will never be iterated over.
While at it, clean up a condition alignment.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190117153411.2390-2-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The percpu members of struct sd_data and s_data are declared as:
struct ... ** __percpu member;
So their type is:
__percpu pointer to pointer to struct ...
But looking at how they're used, their type should be:
pointer to __percpu pointer to struct ...
and they should thus be declared as:
struct ... * __percpu *member;
So fix the placement of '__percpu' in the definition of these
structures.
This addresses a bunch of Sparse's warnings like:
warning: incorrect type in initializer (different address spaces)
expected void const [noderef] <asn:3> *__vpp_verify
got struct sched_domain **
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190118144936.79158-1-luc.vanoostenryck@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since commit:
d03266910a ("sched/fair: Fix task group initialization")
the utilization of a sched entity representing a task group is no longer
initialized to any other value than 0. So post_init_entity_util_avg() is
only used for tasks, not for sched_entities.
Make this clear by calling it with a task_struct pointer argument which
also eliminates the entity_is_task(se) if condition in the fork path and
get rid of the stale comment in remove_entity_load_avg() accordingly.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190122162501.12000-1-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This re-applies the commit reverted here:
commit c40f7d74c7 ("sched/fair: Fix infinite loop in update_blocked_averages() by reverting a9e7f6544b9c")
I.e. now that cfs_rq can be safely removed/added in the list, we can re-apply:
commit a9e7f6544b ("sched/fair: Fix O(nr_cgroups) in load balance path")
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: sargun@sargun.me
Cc: tj@kernel.org
Cc: xiexiuqi@huawei.com
Cc: xiezhipeng1@huawei.com
Link: https://lkml.kernel.org/r/1549469662-13614-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Removing a cfs_rq from rq->leaf_cfs_rq_list can break the parent/child
ordering of the list when it will be added back. In order to remove an
empty and fully decayed cfs_rq, we must remove its children too, so they
will be added back in the right order next time.
With a normal decay of PELT, a parent will be empty and fully decayed
if all children are empty and fully decayed too. In such a case, we just
have to ensure that the whole branch will be added when a new task is
enqueued. This is default behavior since :
commit f678331973 ("sched/fair: Fix insertion in rq->leaf_cfs_rq_list")
In case of throttling, the PELT of throttled cfs_rq will not be updated
whereas the parent will. This breaks the assumption made above unless we
remove the children of a cfs_rq that is throttled. Then, they will be
added back when unthrottled and a sched_entity will be enqueued.
As throttled cfs_rq are now removed from the list, we can remove the
associated test in update_blocked_averages().
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: sargun@sargun.me
Cc: tj@kernel.org
Cc: xiexiuqi@huawei.com
Cc: xiezhipeng1@huawei.com
Link: https://lkml.kernel.org/r/1549469662-13614-2-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This series finally gets us to the point of having system calls with
64-bit time_t on all architectures, after a long time of incremental
preparation patches.
There was actually one conversion that I missed during the summer,
i.e. Deepa's timex series, which I now updated based the 5.0-rc1 changes
and review comments.
The following system calls are now added on all 32-bit architectures
using the same system call numbers:
403 clock_gettime64
404 clock_settime64
405 clock_adjtime64
406 clock_getres_time64
407 clock_nanosleep_time64
408 timer_gettime64
409 timer_settime64
410 timerfd_gettime64
411 timerfd_settime64
412 utimensat_time64
413 pselect6_time64
414 ppoll_time64
416 io_pgetevents_time64
417 recvmmsg_time64
418 mq_timedsend_time64
419 mq_timedreceiv_time64
420 semtimedop_time64
421 rt_sigtimedwait_time64
422 futex_time64
423 sched_rr_get_interval_time64
Each one of these corresponds directly to an existing system call
that includes a 'struct timespec' argument, or a structure containing
a timespec or (in case of clock_adjtime) timeval. Not included here
are new versions of getitimer/setitimer and getrusage/waitid, which
are planned for the future but only needed to make a consistent API
rather than for correct operation beyond y2038. These four system
calls are based on 'timeval', and it has not been finally decided
what the replacement kernel interface will use instead.
So far, I have done a lot of build testing across most architectures,
which has found a number of bugs. Runtime testing so far included
testing LTP on 32-bit ARM with the existing system calls, to ensure
we do not regress for existing binaries, and a test with a 32-bit
x86 build of LTP against a modified version of the musl C library
that has been adapted to the new system call interface [3].
This library can be used for testing on all architectures supported
by musl-1.1.21, but it is not how the support is getting integrated
into the official musl release. Official musl support is planned
but will require more invasive changes to the library.
Link: https://lore.kernel.org/lkml/20190110162435.309262-1-arnd@arndb.de/T/
Link: https://lore.kernel.org/lkml/20190118161835.2259170-1-arnd@arndb.de/
Link: https://git.linaro.org/people/arnd/musl-y2038.git/ [2]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2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=IZVb
-----END PGP SIGNATURE-----
Merge tag 'y2038-new-syscalls' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground into timers/2038
Pull y2038 - time64 system calls from Arnd Bergmann:
This series finally gets us to the point of having system calls with 64-bit
time_t on all architectures, after a long time of incremental preparation
patches.
There was actually one conversion that I missed during the summer,
i.e. Deepa's timex series, which I now updated based the 5.0-rc1 changes
and review comments.
The following system calls are now added on all 32-bit architectures using
the same system call numbers:
403 clock_gettime64
404 clock_settime64
405 clock_adjtime64
406 clock_getres_time64
407 clock_nanosleep_time64
408 timer_gettime64
409 timer_settime64
410 timerfd_gettime64
411 timerfd_settime64
412 utimensat_time64
413 pselect6_time64
414 ppoll_time64
416 io_pgetevents_time64
417 recvmmsg_time64
418 mq_timedsend_time64
419 mq_timedreceiv_time64
420 semtimedop_time64
421 rt_sigtimedwait_time64
422 futex_time64
423 sched_rr_get_interval_time64
Each one of these corresponds directly to an existing system call that
includes a 'struct timespec' argument, or a structure containing a timespec
or (in case of clock_adjtime) timeval. Not included here are new versions
of getitimer/setitimer and getrusage/waitid, which are planned for the
future but only needed to make a consistent API rather than for correct
operation beyond y2038. These four system calls are based on 'timeval', and
it has not been finally decided what the replacement kernel interface will
use instead.
So far, I have done a lot of build testing across most architectures, which
has found a number of bugs. Runtime testing so far included testing LTP on
32-bit ARM with the existing system calls, to ensure we do not regress for
existing binaries, and a test with a 32-bit x86 build of LTP against a
modified version of the musl C library that has been adapted to the new
system call interface [3]. This library can be used for testing on all
architectures supported by musl-1.1.21, but it is not how the support is
getting integrated into the official musl release. Official musl support is
planned but will require more invasive changes to the library.
Link: https://lore.kernel.org/lkml/20190110162435.309262-1-arnd@arndb.de/T/
Link: https://lore.kernel.org/lkml/20190118161835.2259170-1-arnd@arndb.de/
Link: https://git.linaro.org/people/arnd/musl-y2038.git/ [2]
A lot of system calls that pass a time_t somewhere have an implementation
using a COMPAT_SYSCALL_DEFINEx() on 64-bit architectures, and have
been reworked so that this implementation can now be used on 32-bit
architectures as well.
The missing step is to redefine them using the regular SYSCALL_DEFINEx()
to get them out of the compat namespace and make it possible to build them
on 32-bit architectures.
Any system call that ends in 'time' gets a '32' suffix on its name for
that version, while the others get a '_time32' suffix, to distinguish
them from the normal version, which takes a 64-bit time argument in the
future.
In this step, only 64-bit architectures are changed, doing this rename
first lets us avoid touching the 32-bit architectures twice.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Sargun reported a crash:
"I picked up c40f7d74c7 sched/fair: Fix
infinite loop in update_blocked_averages() by reverting a9e7f6544b
and put it on top of 4.19.13. In addition to this, I uninlined
list_add_leaf_cfs_rq for debugging.
This revealed a new bug that we didn't get to because we kept getting
crashes from the previous issue. When we are running with cgroups that
are rapidly changing, with CFS bandwidth control, and in addition
using the cpusets cgroup, we see this crash. Specifically, it seems to
occur with cgroups that are throttled and we change the allowed
cpuset."
The algorithm used to order cfs_rq in rq->leaf_cfs_rq_list assumes that
it will walk down to root the 1st time a cfs_rq is used and we will finish
to add either a cfs_rq without parent or a cfs_rq with a parent that is
already on the list. But this is not always true in presence of throttling.
Because a cfs_rq can be throttled even if it has never been used but other CPUs
of the cgroup have already used all the bandwdith, we are not sure to go down to
the root and add all cfs_rq in the list.
Ensure that all cfs_rq will be added in the list even if they are throttled.
[ mingo: Fix !CGROUPS build. ]
Reported-by: Sargun Dhillon <sargun@sargun.me>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: tj@kernel.org
Fixes: 9c2791f936 ("Fix hierarchical order in rq->leaf_cfs_rq_list")
Link: https://lkml.kernel.org/r/1548825767-10799-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The magic in list_add_leaf_cfs_rq() requires that at the end of
enqueue_task_fair():
rq->tmp_alone_branch == &rq->lead_cfs_rq_list
If this is violated, list integrity is compromised for list entries
and the tmp_alone_branch pointer might dangle.
Also, reflow list_add_leaf_cfs_rq() while there. This looses one
indentation level and generates a form that's convenient for the next
patch.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
move_queued_task() synchronizes with task_rq_lock() as follows:
move_queued_task() task_rq_lock()
[S] ->on_rq = MIGRATING [L] rq = task_rq()
WMB (__set_task_cpu()) ACQUIRE (rq->lock);
[S] ->cpu = new_cpu [L] ->on_rq
where "[L] rq = task_rq()" is ordered before "ACQUIRE (rq->lock)" by an
address dependency and, in turn, "ACQUIRE (rq->lock)" is ordered before
"[L] ->on_rq" by the ACQUIRE itself.
Use READ_ONCE() to load ->cpu in task_rq() (c.f., task_cpu()) to honor
this address dependency. Also, mark the accesses to ->cpu and ->on_rq
with READ_ONCE()/WRITE_ONCE() to comply with the LKMM.
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/20190121155240.27173-1-andrea.parri@amarulasolutions.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
register_sched_domain_sysctl() copies the cpu_possible_mask into
sd_sysctl_cpus, but only if sd_sysctl_cpus hasn't already been
allocated (ie, CONFIG_CPUMASK_OFFSTACK is set). However, when
CONFIG_CPUMASK_OFFSTACK is not set, sd_sysctl_cpus is left
uninitialized (all zeroes) and the kernel may fail to initialize
sched_domain sysctl entries for all possible CPUs.
This is visible to the user if the kernel is booted with maxcpus=n, or
if ACPI tables have been modified to leave CPUs offline, and then
checking for missing /proc/sys/kernel/sched_domain/cpu* entries.
Fix this by separating the allocation and initialization, and adding a
flag to initialize the possible CPU entries while system booting only.
Tested-by: Syuuichirou Ishii <ishii.shuuichir@jp.fujitsu.com>
Tested-by: Tarumizu, Kohei <tarumizu.kohei@jp.fujitsu.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190129151245.5073-1-msys.mizuma@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
util_est is mainly meant to be a lower-bound for tasks utilization.
That's why task_util_est() returns the actual util_avg when it's higher
than the estimated utilization.
With new invaraince signal and without any special check on samples
collection, if a task is limited because of thermal capping for
example, we could end up overestimating its utilization and thus
perhaps generating an unwanted frequency spike when the capping is
relaxed... and (even worst) it will take some more activations for the
estimated utilization to converge back to the actual utilization.
Since we cannot easily know if there is idle time in a CPU when a task
completes an activation with a utilization higher then the CPU capacity,
we skip the sampling when utilization is higher than CPU's capacity.
Suggested-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: pjt@google.com
Cc: pkondeti@codeaurora.org
Cc: quentin.perret@arm.com
Cc: rjw@rjwysocki.net
Cc: srinivas.pandruvada@linux.intel.com
Cc: thara.gopinath@linaro.org
Link: https://lkml.kernel.org/r/1548257214-13745-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The current implementation of load tracking invariance scales the
contribution with current frequency and uarch performance (only for
utilization) of the CPU. One main result of this formula is that the
figures are capped by current capacity of CPU. Another one is that the
load_avg is not invariant because not scaled with uarch.
The util_avg of a periodic task that runs r time slots every p time slots
varies in the range :
U * (1-y^r)/(1-y^p) * y^i < Utilization < U * (1-y^r)/(1-y^p)
with U is the max util_avg value = SCHED_CAPACITY_SCALE
At a lower capacity, the range becomes:
U * C * (1-y^r')/(1-y^p) * y^i' < Utilization < U * C * (1-y^r')/(1-y^p)
with C reflecting the compute capacity ratio between current capacity and
max capacity.
so C tries to compensate changes in (1-y^r') but it can't be accurate.
Instead of scaling the contribution value of PELT algo, we should scale the
running time. The PELT signal aims to track the amount of computation of
tasks and/or rq so it seems more correct to scale the running time to
reflect the effective amount of computation done since the last update.
In order to be fully invariant, we need to apply the same amount of
running time and idle time whatever the current capacity. Because running
at lower capacity implies that the task will run longer, we have to ensure
that the same amount of idle time will be applied when system becomes idle
and no idle time has been "stolen". But reaching the maximum utilization
value (SCHED_CAPACITY_SCALE) means that the task is seen as an
always-running task whatever the capacity of the CPU (even at max compute
capacity). In this case, we can discard this "stolen" idle times which
becomes meaningless.
In order to achieve this time scaling, a new clock_pelt is created per rq.
The increase of this clock scales with current capacity when something
is running on rq and synchronizes with clock_task when rq is idle. With
this mechanism, we ensure the same running and idle time whatever the
current capacity. This also enables to simplify the pelt algorithm by
removing all references of uarch and frequency and applying the same
contribution to utilization and loads. Furthermore, the scaling is done
only once per update of clock (update_rq_clock_task()) instead of during
each update of sched_entities and cfs/rt/dl_rq of the rq like the current
implementation. This is interesting when cgroup are involved as shown in
the results below:
On a hikey (octo Arm64 platform).
Performance cpufreq governor and only shallowest c-state to remove variance
generated by those power features so we only track the impact of pelt algo.
each test runs 16 times:
./perf bench sched pipe
(higher is better)
kernel tip/sched/core + patch
ops/seconds ops/seconds diff
cgroup
root 59652(+/- 0.18%) 59876(+/- 0.24%) +0.38%
level1 55608(+/- 0.27%) 55923(+/- 0.24%) +0.57%
level2 52115(+/- 0.29%) 52564(+/- 0.22%) +0.86%
hackbench -l 1000
(lower is better)
kernel tip/sched/core + patch
duration(sec) duration(sec) diff
cgroup
root 4.453(+/- 2.37%) 4.383(+/- 2.88%) -1.57%
level1 4.859(+/- 8.50%) 4.830(+/- 7.07%) -0.60%
level2 5.063(+/- 9.83%) 4.928(+/- 9.66%) -2.66%
Then, the responsiveness of PELT is improved when CPU is not running at max
capacity with this new algorithm. I have put below some examples of
duration to reach some typical load values according to the capacity of the
CPU with current implementation and with this patch. These values has been
computed based on the geometric series and the half period value:
Util (%) max capacity half capacity(mainline) half capacity(w/ patch)
972 (95%) 138ms not reachable 276ms
486 (47.5%) 30ms 138ms 60ms
256 (25%) 13ms 32ms 26ms
On my hikey (octo Arm64 platform) with schedutil governor, the time to
reach max OPP when starting from a null utilization, decreases from 223ms
with current scale invariance down to 121ms with the new algorithm.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: patrick.bellasi@arm.com
Cc: pjt@google.com
Cc: pkondeti@codeaurora.org
Cc: quentin.perret@arm.com
Cc: rjw@rjwysocki.net
Cc: srinivas.pandruvada@linux.intel.com
Cc: thara.gopinath@linaro.org
Link: https://lkml.kernel.org/r/1548257214-13745-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Some users, specifically futexes and rwsems, required fixes
that allowed the callers to be safe when wakeups occur before
they are expected by wake_up_q(). Such scenarios also play
games and rely on reference counting, and until now were
pivoting on wake_q doing it. With the wake_q_add() call being
moved down, this can no longer be the case. As such we end up
with a a double task refcounting overhead; and these callers
care enough about this (being rather core-ish).
This patch introduces a wake_q_add_safe() call that serves
for callers that have already done refcounting and therefore the
task is 'safe' from wake_q point of view (int that it requires
reference throughout the entire queue/>wakeup cycle). In the one
case it has internal reference counting, in the other case it
consumes the reference counting.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Xie Yongji <xieyongji@baidu.com>
Cc: Yongji Xie <elohimes@gmail.com>
Cc: andrea.parri@amarulasolutions.com
Cc: lilin24@baidu.com
Cc: liuqi16@baidu.com
Cc: nixun@baidu.com
Cc: yuanlinsi01@baidu.com
Cc: zhangyu31@baidu.com
Link: https://lkml.kernel.org/r/20181218195352.7orq3upiwfdbrdne@linux-r8p5
Signed-off-by: Ingo Molnar <mingo@kernel.org>
atomic_t variables are currently used to implement reference
counters with the following properties:
- counter is initialized to 1 using atomic_set()
- a resource is freed upon counter reaching zero
- once counter reaches zero, its further
increments aren't allowed
- counter schema uses basic atomic operations
(set, inc, inc_not_zero, dec_and_test, etc.)
Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.
The variable numa_group.refcount is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
** Important note for maintainers:
Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.
The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.
Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.
Please double check that you don't have some undocumented
memory guarantees for this variable usage.
For the numa_group.refcount it might make a difference
in following places:
- get_numa_group(): increment in refcount_inc_not_zero() only
guarantees control dependency on success vs. fully ordered
atomic counterpart
- put_numa_group(): decrement in refcount_dec_and_test() only
provides RELEASE ordering and control dependency on success
vs. fully ordered atomic counterpart
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1547814450-18902-4-git-send-email-elena.reshetova@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull cpu hotplug fixes from Thomas Gleixner:
"Two fixes for the cpu hotplug machinery:
- Replace the overly clever 'SMT disabled by BIOS' detection logic as
it breaks KVM scenarios and prevents speculation control updates
when the Hyperthreads are brought online late after boot.
- Remove a redundant invocation of the speculation control update
function"
* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM
x86/speculation: Remove redundant arch_smt_update() invocation
psi has provisions to shut off the periodic aggregation worker when
there is a period of no task activity - and thus no data that needs
aggregating. However, while developing psi monitoring, Suren noticed
that the aggregation clock currently won't stay shut off for good.
Debugging this revealed a flaw in the idle design: an aggregation run
will see no task activity and decide to go to sleep; shortly thereafter,
the kworker thread that executed the aggregation will go idle and cause
a scheduling change, during which the psi callback will kick the
!pending worker again. This will ping-pong forever, and is equivalent
to having no shut-off logic at all (but with more code!)
Fix this by exempting aggregation workers from psi's clock waking logic
when the state change is them going to sleep. To do this, tag workers
with the last work function they executed, and if in psi we see a worker
going to sleep after aggregating psi data, we will not reschedule the
aggregation work item.
What if the worker is also executing other items before or after?
Any psi state times that were incurred by work items preceding the
aggregation work will have been collected from the per-cpu buckets
during the aggregation itself. If there are work items following the
aggregation work, the worker's last_func tag will be overwritten and the
aggregator will be kept alive to process this genuine new activity.
If the aggregation work is the last thing the worker does, and we decide
to go idle, the brief period of non-idle time incurred between the
aggregation run and the kworker's dequeue will be stranded in the
per-cpu buckets until the clock is woken by later activity. But that
should not be a problem. The buckets can hold 4s worth of time, and
future activity will wake the clock with a 2s delay, giving us 2s worth
of data we can leave behind when disabling aggregation. If it takes a
worker more than two seconds to go idle after it finishes its last work
item, we likely have bigger problems in the system, and won't notice one
sample that was averaged with a bogus per-CPU weight.
Link: http://lkml.kernel.org/r/20190116193501.1910-1-hannes@cmpxchg.org
Fixes: eb414681d5 ("psi: pressure stall information for CPU, memory, and IO")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the following commit:
73d5e2b472 ("cpu/hotplug: detect SMT disabled by BIOS")
... the hotplug code attempted to detect when SMT was disabled by BIOS,
in which case it reported SMT as permanently disabled. However, that
code broke a virt hotplug scenario, where the guest is booted with only
primary CPU threads, and a sibling is brought online later.
The problem is that there doesn't seem to be a way to reliably
distinguish between the HW "SMT disabled by BIOS" case and the virt
"sibling not yet brought online" case. So the above-mentioned commit
was a bit misguided, as it permanently disabled SMT for both cases,
preventing future virt sibling hotplugs.
Going back and reviewing the original problems which were attempted to
be solved by that commit, when SMT was disabled in BIOS:
1) /sys/devices/system/cpu/smt/control showed "on" instead of
"notsupported"; and
2) vmx_vm_init() was incorrectly showing the L1TF_MSG_SMT warning.
I'd propose that we instead consider #1 above to not actually be a
problem. Because, at least in the virt case, it's possible that SMT
wasn't disabled by BIOS and a sibling thread could be brought online
later. So it makes sense to just always default the smt control to "on"
to allow for that possibility (assuming cpuid indicates that the CPU
supports SMT).
The real problem is #2, which has a simple fix: change vmx_vm_init() to
query the actual current SMT state -- i.e., whether any siblings are
currently online -- instead of looking at the SMT "control" sysfs value.
So fix it by:
a) reverting the original "fix" and its followup fix:
73d5e2b472 ("cpu/hotplug: detect SMT disabled by BIOS")
bc2d8d262c ("cpu/hotplug: Fix SMT supported evaluation")
and
b) changing vmx_vm_init() to query the actual current SMT state --
instead of the sysfs control value -- to determine whether the L1TF
warning is needed. This also requires the 'sched_smt_present'
variable to exported, instead of 'cpu_smt_control'.
Fixes: 73d5e2b472 ("cpu/hotplug: detect SMT disabled by BIOS")
Reported-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Joe Mario <jmario@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kvm@vger.kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/e3a85d585da28cc333ecbc1e78ee9216e6da9396.1548794349.git.jpoimboe@redhat.com
In case of active balancing, we increase the balance interval to cover
pinned tasks cases not covered by all_pinned logic. Neverthless, the
active migration triggered by asym packing should be treated as the normal
unbalanced case and reset the interval to default value, otherwise active
migration for asym_packing can be easily delayed for hundreds of ms
because of this pinned task detection mechanism.
The same happens to other conditions tested in need_active_balance() like
misfit task and when the capacity of src_cpu is reduced compared to
dst_cpu (see comments in need_active_balance() for details).
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: valentin.schneider@arm.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When check_asym_packing() is triggered, the imbalance is set to:
busiest_stat.avg_load * busiest_stat.group_capacity / SCHED_CAPACITY_SCALE
But busiest_stat.avg_load equals:
sgs->group_load * SCHED_CAPACITY_SCALE / sgs->group_capacity
These divisions can generate a rounding that will make imbalance
slightly lower than the weighted load of the cfs_rq. But this is
enough to skip the rq in find_busiest_queue() and prevents asym
migration from happening.
Directly set imbalance to busiest's sgs->group_load to remove the
rounding.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: valentin.schneider@arm.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Newly idle load balancing is not always triggered when a CPU becomes idle.
This prevents the scheduler from getting a chance to migrate the task
for asym packing.
Enable active migration during idle load balance too.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: valentin.schneider@arm.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Traditionally hrtimer callbacks were run with IRQs disabled, but with
the introduction of HRTIMER_MODE_SOFT it is possible they run from
SoftIRQ context, which does _NOT_ have IRQs disabled.
Allow for the CFS bandwidth timers (period_timer and slack_timer) to
be ran from SoftIRQ context; this entails removing the assumption that
IRQs are already disabled from the locking.
While mainline doesn't strictly need this, -RT forces all timers not
explicitly marked with MODE_HARD into MODE_SOFT and trips over this.
And marking these timers as MODE_HARD doesn't make sense as they're
not required for RT operation and can potentially be quite expensive.
Reported-by: Tom Putzeys <tom.putzeys@be.atlascopco.com>
Tested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190107125231.GE14122@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
All that fancy new Energy-Aware scheduling foo is hidden behind a
static_key, which is awesome if you have the stuff enabled in your
config.
However, when you lack all the prerequisites it doesn't make any sense
to pretend we'll ever actually run this, so provide a little more clue
to the compiler so it can more agressively delete the code.
text data bss dec hex filename
50297 976 96 51369 c8a9 defconfig-build/kernel/sched/fair.o
49227 944 96 50267 c45b defconfig-build/kernel/sched/fair.o
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that synchronize_rcu() waits for preempt-disable regions of
code as well as RCU read-side critical sections, synchronize_sched()
can be replaced by synchronize_rcu(), in fact, synchronize_sched()
is now completely equivalent to synchronize_rcu(). This commit
therefore replaces synchronize_sched() with synchronize_rcu() so that
synchronize_sched() can eventually be removed entirely.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Now that call_rcu()'s callback is not invoked until after all
preempt-disable regions of code have completed (in addition to explicitly
marked RCU read-side critical sections), call_rcu() can be used in place
of call_rcu_sched(). This commit therefore makes that change.
While in the area, this commit also updates an outdated header comment
for for_each_domain().
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
The cmpxchg() will fail when the task is already in the process
of waking up, and as such is an extremely rare occurrence.
Micro-optimize the call and put an unlikely() around it.
To no surprise, when using CONFIG_PROFILE_ANNOTATED_BRANCHES
under a number of workloads the incorrect rate was a mere 1-2%.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yongji Xie <elohimes@gmail.com>
Cc: andrea.parri@amarulasolutions.com
Cc: lilin24@baidu.com
Cc: liuqi16@baidu.com
Cc: nixun@baidu.com
Cc: xieyongji@baidu.com
Cc: yuanlinsi01@baidu.com
Cc: zhangyu31@baidu.com
Link: https://lkml.kernel.org/r/20181203053130.gwkw6kg72azt2npb@linux-r8p5
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Notable cmpxchg() does not provide ordering when it fails, however
wake_q_add() requires ordering in this specific case too. Without this
it would be possible for the concurrent wakeup to not observe our
prior state.
Andrea Parri provided:
C wake_up_q-wake_q_add
{
int next = 0;
int y = 0;
}
P0(int *next, int *y)
{
int r0;
/* in wake_up_q() */
WRITE_ONCE(*next, 1); /* node->next = NULL */
smp_mb(); /* implied by wake_up_process() */
r0 = READ_ONCE(*y);
}
P1(int *next, int *y)
{
int r1;
/* in wake_q_add() */
WRITE_ONCE(*y, 1); /* wake_cond = true */
smp_mb__before_atomic();
r1 = cmpxchg_relaxed(next, 1, 2);
}
exists (0:r0=0 /\ 1:r1=0)
This "exists" clause cannot be satisfied according to the LKMM:
Test wake_up_q-wake_q_add Allowed
States 3
0:r0=0; 1:r1=1;
0:r0=1; 1:r1=0;
0:r0=1; 1:r1=1;
No
Witnesses
Positive: 0 Negative: 3
Condition exists (0:r0=0 /\ 1:r1=0)
Observation wake_up_q-wake_q_add Never 0 3
Reported-by: Yongji Xie <elohimes@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The only guarantee provided by wake_q_add() is that a wakeup will
happen after it, it does _NOT_ guarantee the wakeup will be delayed
until the matching wake_up_q().
If wake_q_add() fails the cmpxchg() a concurrent wakeup is pending and
that can happen at any time after the cmpxchg(). This means we should
not rely on the wakeup happening at wake_q_up(), but should be ready
for wake_q_add() to issue the wakeup.
The delay; if provided (most likely); should only result in more efficient
behaviour.
Reported-by: Yongji Xie <elohimes@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label".
The jump label is controlled by HAVE_JUMP_LABEL, which is defined
like this:
#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
# define HAVE_JUMP_LABEL
#endif
We can improve this by testing 'asm goto' support in Kconfig, then
make JUMP_LABEL depend on CC_HAS_ASM_GOTO.
Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will
match to the real kernel capability.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Merge more updates from Andrew Morton:
- procfs updates
- various misc bits
- lib/ updates
- epoll updates
- autofs
- fatfs
- a few more MM bits
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (58 commits)
mm/page_io.c: fix polled swap page in
checkpatch: add Co-developed-by to signature tags
docs: fix Co-Developed-by docs
drivers/base/platform.c: kmemleak ignore a known leak
fs: don't open code lru_to_page()
fs/: remove caller signal_pending branch predictions
mm/: remove caller signal_pending branch predictions
arch/arc/mm/fault.c: remove caller signal_pending_branch predictions
kernel/sched/: remove caller signal_pending branch predictions
kernel/locking/mutex.c: remove caller signal_pending branch predictions
mm: select HAVE_MOVE_PMD on x86 for faster mremap
mm: speed up mremap by 20x on large regions
mm: treewide: remove unused address argument from pte_alloc functions
initramfs: cleanup incomplete rootfs
scripts/gdb: fix lx-version string output
kernel/kcov.c: mark write_comp_data() as notrace
kernel/sysctl: add panic_print into sysctl
panic: add options to print system info when panic happens
bfs: extra sanity checking and static inode bitmap
exec: separate MM_ANONPAGES and RLIMIT_STACK accounting
...
This is already done for us internally by the signal machinery.
Link: http://lkml.kernel.org/r/20181116002713.8474-3-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.
It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access. But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.
A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model. And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.
This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.
There were a couple of notable cases:
- csky still had the old "verify_area()" name as an alias.
- the iter_iov code had magical hardcoded knowledge of the actual
values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
really used it)
- microblaze used the type argument for a debug printout
but other than those oddities this should be a total no-op patch.
I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something. Any missed conversion should be trivially fixable, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Zhipeng Xie, Xie XiuQi and Sargun Dhillon reported lockups in the
scheduler under high loads, starting at around the v4.18 time frame,
and Zhipeng Xie tracked it down to bugs in the rq->leaf_cfs_rq_list
manipulation.
Do a (manual) revert of:
a9e7f6544b ("sched/fair: Fix O(nr_cgroups) in load balance path")
It turns out that the list_del_leaf_cfs_rq() introduced by this commit
is a surprising property that was not considered in followup commits
such as:
9c2791f936 ("sched/fair: Fix hierarchical order in rq->leaf_cfs_rq_list")
As Vincent Guittot explains:
"I think that there is a bigger problem with commit a9e7f6544b and
cfs_rq throttling:
Let take the example of the following topology TG2 --> TG1 --> root:
1) The 1st time a task is enqueued, we will add TG2 cfs_rq then TG1
cfs_rq to leaf_cfs_rq_list and we are sure to do the whole branch in
one path because it has never been used and can't be throttled so
tmp_alone_branch will point to leaf_cfs_rq_list at the end.
2) Then TG1 is throttled
3) and we add TG3 as a new child of TG1.
4) The 1st enqueue of a task on TG3 will add TG3 cfs_rq just before TG1
cfs_rq and tmp_alone_branch will stay on rq->leaf_cfs_rq_list.
With commit a9e7f6544b, we can del a cfs_rq from rq->leaf_cfs_rq_list.
So if the load of TG1 cfs_rq becomes NULL before step 2) above, TG1
cfs_rq is removed from the list.
Then at step 4), TG3 cfs_rq is added at the beginning of rq->leaf_cfs_rq_list
but tmp_alone_branch still points to TG3 cfs_rq because its throttled
parent can't be enqueued when the lock is released.
tmp_alone_branch doesn't point to rq->leaf_cfs_rq_list whereas it should.
So if TG3 cfs_rq is removed or destroyed before tmp_alone_branch
points on another TG cfs_rq, the next TG cfs_rq that will be added,
will be linked outside rq->leaf_cfs_rq_list - which is bad.
In addition, we can break the ordering of the cfs_rq in
rq->leaf_cfs_rq_list but this ordering is used to update and
propagate the update from leaf down to root."
Instead of trying to work through all these cases and trying to reproduce
the very high loads that produced the lockup to begin with, simplify
the code temporarily by reverting a9e7f6544b - which change was clearly
not thought through completely.
This (hopefully) gives us a kernel that doesn't lock up so people
can continue to enjoy their holidays without worrying about regressions. ;-)
[ mingo: Wrote changelog, fixed weird spelling in code comment while at it. ]
Analyzed-by: Xie XiuQi <xiexiuqi@huawei.com>
Analyzed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reported-by: Zhipeng Xie <xiezhipeng1@huawei.com>
Reported-by: Sargun Dhillon <sargun@sargun.me>
Reported-by: Xie XiuQi <xiexiuqi@huawei.com>
Tested-by: Zhipeng Xie <xiezhipeng1@huawei.com>
Tested-by: Sargun Dhillon <sargun@sargun.me>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: <stable@vger.kernel.org> # v4.13+
Cc: Bin Li <huawei.libin@huawei.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: a9e7f6544b ("sched/fair: Fix O(nr_cgroups) in load balance path")
Link: http://lkml.kernel.org/r/1545879866-27809-1-git-send-email-xiexiuqi@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Caused by making the variable static:
kernel/sched/fair.c:119:21: warning: 'capacity_margin' defined but not used [-Wunused-variable]
Seems easiest to just move it up under the existing ifdef CONFIG_SMP
that's a few lines above.
Fixes: ed8885a144 ('sched/fair: Make some variables static')
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle were:
- Introduce "Energy Aware Scheduling" - by Quentin Perret.
This is a coherent topology description of CPUs in cooperation with
the PM subsystem, with the goal to schedule more energy-efficiently
on asymetric SMP platform - such as waking up tasks to the more
energy-efficient CPUs first, as long as the system isn't
oversubscribed.
For details of the design, see:
https://lore.kernel.org/lkml/20180724122521.22109-1-quentin.perret@arm.com/
- Misc cleanups and smaller enhancements"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
sched/fair: Select an energy-efficient CPU on task wake-up
sched/fair: Introduce an energy estimation helper function
sched/fair: Add over-utilization/tipping point indicator
sched/fair: Clean-up update_sg_lb_stats parameters
sched/toplogy: Introduce the 'sched_energy_present' static key
sched/topology: Make Energy Aware Scheduling depend on schedutil
sched/topology: Disable EAS on inappropriate platforms
sched/topology: Add lowest CPU asymmetry sched_domain level pointer
sched/topology: Reference the Energy Model of CPUs when available
PM: Introduce an Energy Model management framework
sched/cpufreq: Prepare schedutil for Energy Aware Scheduling
sched/topology: Relocate arch_scale_cpu_capacity() to the internal header
sched/core: Remove unnecessary unlikely() in push_*_task()
sched/topology: Remove the ::smt_gain field from 'struct sched_domain'
sched: Fix various typos in comments
sched/core: Clean up the #ifdef block in add_nr_running()
sched/fair: Make some variables static
sched/core: Create task_has_idle_policy() helper
sched/fair: Add lsub_positive() and use it consistently
sched/fair: Mask UTIL_AVG_UNCHANGED usages
...
Pull locking updates from Ingo Molnar:
"The main change in this cycle are initial preparatory bits of dynamic
lockdep keys support from Bart Van Assche.
There are also misc changes, a comment cleanup and a data structure
cleanup"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Clean up comment in nohz_idle_balance()
locking/lockdep: Stop using RCU primitives to access 'all_lock_classes'
locking/lockdep: Make concurrent lockdep_reset_lock() calls safe
locking/lockdep: Remove a superfluous INIT_LIST_HEAD() statement
locking/lockdep: Introduce lock_class_cache_is_registered()
locking/lockdep: Inline __lockdep_init_map()
locking/lockdep: Declare local symbols static
tools/lib/lockdep/tests: Test the lockdep_reset_lock() implementation
tools/lib/lockdep: Add dummy print_irqtrace_events() implementation
tools/lib/lockdep: Rename "trywlock" into "trywrlock"
tools/lib/lockdep/tests: Run lockdep tests a second time under Valgrind
tools/lib/lockdep/tests: Improve testing accuracy
tools/lib/lockdep/tests: Fix shellcheck warnings
tools/lib/lockdep/tests: Display compiler warning and error messages
locking/lockdep: Remove ::version from lock_class structure
Pull RCU updates from Ingo Molnar:
"The biggest RCU changes in this cycle were:
- Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar.
- Replace calls of RCU-bh and RCU-sched update-side functions to
their vanilla RCU counterparts. This series is a step towards
complete removal of the RCU-bh and RCU-sched update-side functions.
( Note that some of these conversions are going upstream via their
respective maintainers. )
- Documentation updates, including a number of flavor-consolidation
updates from Joel Fernandes.
- Miscellaneous fixes.
- Automate generation of the initrd filesystem used for rcutorture
testing.
- Convert spin_is_locked() assertions to instead use lockdep.
( Note that some of these conversions are going upstream via their
respective maintainers. )
- SRCU updates, especially including a fix from Dennis Krein for a
bag-on-head-class bug.
- RCU torture-test updates"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (112 commits)
rcutorture: Don't do busted forward-progress testing
rcutorture: Use 100ms buckets for forward-progress callback histograms
rcutorture: Recover from OOM during forward-progress tests
rcutorture: Print forward-progress test age upon failure
rcutorture: Print time since GP end upon forward-progress failure
rcutorture: Print histogram of CB invocation at OOM time
rcutorture: Print GP age upon forward-progress failure
rcu: Print per-CPU callback counts for forward-progress failures
rcu: Account for nocb-CPU callback counts in RCU CPU stall warnings
rcutorture: Dump grace-period diagnostics upon forward-progress OOM
rcutorture: Prepare for asynchronous access to rcu_fwd_startat
torture: Remove unnecessary "ret" variables
rcutorture: Affinity forward-progress test to avoid housekeeping CPUs
rcutorture: Break up too-long rcu_torture_fwd_prog() function
rcutorture: Remove cbflood facility
torture: Bring any extra CPUs online during kernel startup
rcutorture: Add call_rcu() flooding forward-progress tests
rcutorture/formal: Replace synchronize_sched() with synchronize_rcu()
tools/kernel.h: Replace synchronize_sched() with synchronize_rcu()
net/decnet: Replace rcu_barrier_bh() with rcu_barrier()
...
Energy-aware scheduling is only meant to be active while the system is
_not_ over-utilized. That is, there are spare cycles available to shift
tasks around based on their actual utilization to get a more
energy-efficient task distribution without depriving any tasks. When
above the tipping point task placement is done the traditional way based
on load_avg, spreading the tasks across as many cpus as possible based
on priority scaled load to preserve smp_nice. Below the tipping point we
want to use util_avg instead. We need to define a criteria for when we
make the switch.
The util_avg for each cpu converges towards 100% regardless of how many
additional tasks we may put on it. If we define over-utilized as:
sum_{cpus}(rq.cfs.avg.util_avg) + margin > sum_{cpus}(rq.capacity)
some individual cpus may be over-utilized running multiple tasks even
when the above condition is false. That should be okay as long as we try
to spread the tasks out to avoid per-cpu over-utilization as much as
possible and if all tasks have the _same_ priority. If the latter isn't
true, we have to consider priority to preserve smp_nice.
For example, we could have n_cpus nice=-10 util_avg=55% tasks and
n_cpus/2 nice=0 util_avg=60% tasks. Balancing based on util_avg we are
likely to end up with nice=-10 tasks sharing cpus and nice=0 tasks
getting their own as we 1.5*n_cpus tasks in total and 55%+55% is less
over-utilized than 55%+60% for those cpus that have to be shared. The
system utilization is only 85% of the system capacity, but we are
breaking smp_nice.
To be sure not to break smp_nice, we have defined over-utilization
conservatively as when any cpu in the system is fully utilized at its
highest frequency instead:
cpu_rq(any).cfs.avg.util_avg + margin > cpu_rq(any).capacity
IOW, as soon as one cpu is (nearly) 100% utilized, we switch to load_avg
to factor in priority to preserve smp_nice.
With this definition, we can skip periodic load-balance as no cpu has an
always-running task when the system is not over-utilized. All tasks will
be periodic and we can balance them at wake-up. This conservative
condition does however mean that some scenarios that could benefit from
energy-aware decisions even if one cpu is fully utilized would not get
those benefits.
For systems where some cpus might have reduced capacity on some cpus
(RT-pressure and/or big.LITTLE), we want periodic load-balance checks as
soon a just a single cpu is fully utilized as it might one of those with
reduced capacity and in that case we want to migrate it.
[ peterz: Added a comment explaining why new tasks are not accounted during
overutilization detection. ]
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adharmap@codeaurora.org
Cc: chris.redpath@arm.com
Cc: currojerez@riseup.net
Cc: dietmar.eggemann@arm.com
Cc: edubezval@gmail.com
Cc: gregkh@linuxfoundation.org
Cc: javi.merino@kernel.org
Cc: joel@joelfernandes.org
Cc: juri.lelli@redhat.com
Cc: patrick.bellasi@arm.com
Cc: pkondeti@codeaurora.org
Cc: rjw@rjwysocki.net
Cc: skannan@codeaurora.org
Cc: smuckle@google.com
Cc: srinivas.pandruvada@linux.intel.com
Cc: thara.gopinath@linaro.org
Cc: tkjos@google.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Cc: viresh.kumar@linaro.org
Link: https://lkml.kernel.org/r/20181203095628.11858-13-quentin.perret@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
WARN_ON() already contains an unlikely(), so it's not necessary to
use WARN_ON(1).
Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181103172602.1917-1-tiny.windzz@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
::smt_gain is used to compute the capacity of CPUs of a SMT core with the
constraint 1 < ::smt_gain < 2 in order to be able to compute number of CPUs
per core. The field has_free_capacity of struct numa_stat, which was the
last user of this computation of number of CPUs per core, has been removed
by:
2d4056fafa ("sched/numa: Remove numa_has_capacity()")
We can now remove this constraint on core capacity and use the defautl value
SCHED_CAPACITY_SCALE for SMT CPUs. With this remove, SCHED_CAPACITY_SCALE
becomes the maximum compute capacity of CPUs on every systems. This should
help to simplify some code and remove fields like rd->max_cpu_capacity
Furthermore, arch_scale_cpu_capacity() is used with a NULL sd in several other
places in the code when it wants the capacity of a CPUs to scale
some metrics like in pelt, deadline or schedutil. In case on SMT, the value
returned is not the capacity of SMT CPUs but default SCHED_CAPACITY_SCALE.
So remove it.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1535548752-4434-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Concerning the comment associated to the atomic_fetch_andnot() in
nohz_idle_balance(), Vincent explains [1]:
"[...] the comment is useless and can be removed [...] it was
referring to a line code above the comment that was present in
a previous iteration of the patchset. This line disappeared in
final version but the comment has stayed."
So remove the comment.
Vincent also points out that the full ordering associated to the
atomic_fetch_andnot() primitive could be relaxed, but this patch
insists on the current more conservative/fully ordered solution:
"Performance" isn't a concern, stay away from "correctness"/subtle
relaxed (re)ordering if possible..., just make sure not to confuse
the next reader with misleading/out-of-date comments.
[1] http://lkml.kernel.org/r/CAKfTPtBjA-oCBRkO6__npQwL3+HLjzk7riCcPU1R7YdO-EpuZg@mail.gmail.com
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20181127110110.5533-1-andrea.parri@amarulasolutions.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The SPDX tags are not present in cpufreq.c and cpufreq_schedutil.c.
Add them and remove the license descriptions
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Pull RCU changes from Paul E. McKenney:
- Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar.
- Replace calls of RCU-bh and RCU-sched update-side functions
to their vanilla RCU counterparts. This series is a step
towards complete removal of the RCU-bh and RCU-sched update-side
functions.
( Note that some of these conversions are going upstream via their
respective maintainers. )
- Documentation updates, including a number of flavor-consolidation
updates from Joel Fernandes.
- Miscellaneous fixes.
- Automate generation of the initrd filesystem used for
rcutorture testing.
- Convert spin_is_locked() assertions to instead use lockdep.
( Note that some of these conversions are going upstream via their
respective maintainers. )
- SRCU updates, especially including a fix from Dennis Krein
for a bag-on-head-class bug.
- RCU torture-test updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Go over the scheduler source code and fix common typos
in comments - and a typo in an actual variable name.
No change in functionality intended.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull STIBP fallout fixes from Thomas Gleixner:
"The performance destruction department finally got it's act together
and came up with a cure for the STIPB regression:
- Provide a command line option to control the spectre v2 user space
mitigations. Default is either seccomp or prctl (if seccomp is
disabled in Kconfig). prctl allows mitigation opt-in, seccomp
enables the migitation for sandboxed processes.
- Rework the code to handle the conditional STIBP/IBPB control and
remove the now unused ptrace_may_access_sched() optimization
attempt
- Disable STIBP automatically when SMT is disabled
- Optimize the switch_to() logic to avoid MSR writes and invocations
of __switch_to_xtra().
- Make the asynchronous speculation TIF updates synchronous to
prevent stale mitigation state.
As a general cleanup this also makes retpoline directly depend on
compiler support and removes the 'minimal retpoline' option which just
pretended to provide some form of security while providing none"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
x86/speculation: Provide IBPB always command line options
x86/speculation: Add seccomp Spectre v2 user space protection mode
x86/speculation: Enable prctl mode for spectre_v2_user
x86/speculation: Add prctl() control for indirect branch speculation
x86/speculation: Prepare arch_smt_update() for PRCTL mode
x86/speculation: Prevent stale SPEC_CTRL msr content
x86/speculation: Split out TIF update
ptrace: Remove unused ptrace_may_access_sched() and MODE_IBRS
x86/speculation: Prepare for conditional IBPB in switch_mm()
x86/speculation: Avoid __switch_to_xtra() calls
x86/process: Consolidate and simplify switch_to_xtra() code
x86/speculation: Prepare for per task indirect branch speculation control
x86/speculation: Add command line control for indirect branch speculation
x86/speculation: Unify conditional spectre v2 print functions
x86/speculataion: Mark command line parser data __initdata
x86/speculation: Mark string arrays const correctly
x86/speculation: Reorder the spec_v2 code
x86/l1tf: Show actual SMT state
x86/speculation: Rework SMT state change
sched/smt: Expose sched_smt_present static key
...
Mel Gorman reports a hackbench regression with psi that would prohibit
shipping the suse kernel with it default-enabled, but he'd still like
users to be able to opt in at little to no cost to others.
With the current combination of CONFIG_PSI and the psi_disabled bool set
from the commandline, this is a challenge. Do the following things to
make it easier:
1. Add a config option CONFIG_PSI_DEFAULT_DISABLED that allows distros
to enable CONFIG_PSI in their kernel but leave the feature disabled
unless a user requests it at boot-time.
To avoid double negatives, rename psi_disabled= to psi=.
2. Make psi_disabled a static branch to eliminate any branch costs
when the feature is disabled.
In terms of numbers before and after this patch, Mel says:
: The following is a comparision using CONFIG_PSI=n as a baseline against
: your patch and a vanilla kernel
:
: 4.20.0-rc4 4.20.0-rc4 4.20.0-rc4
: kconfigdisable-v1r1 vanilla psidisable-v1r1
: Amean 1 1.3100 ( 0.00%) 1.3923 ( -6.28%) 1.3427 ( -2.49%)
: Amean 3 3.8860 ( 0.00%) 4.1230 * -6.10%* 3.8860 ( -0.00%)
: Amean 5 6.8847 ( 0.00%) 8.0390 * -16.77%* 6.7727 ( 1.63%)
: Amean 7 9.9310 ( 0.00%) 10.8367 * -9.12%* 9.9910 ( -0.60%)
: Amean 12 16.6577 ( 0.00%) 18.2363 * -9.48%* 17.1083 ( -2.71%)
: Amean 18 26.5133 ( 0.00%) 27.8833 * -5.17%* 25.7663 ( 2.82%)
: Amean 24 34.3003 ( 0.00%) 34.6830 ( -1.12%) 32.0450 ( 6.58%)
: Amean 30 40.0063 ( 0.00%) 40.5800 ( -1.43%) 41.5087 ( -3.76%)
: Amean 32 40.1407 ( 0.00%) 41.2273 ( -2.71%) 39.9417 ( 0.50%)
:
: It's showing that the vanilla kernel takes a hit (as the bisection
: indicated it would) and that disabling PSI by default is reasonably
: close in terms of performance for this particular workload on this
: particular machine so;
Link: http://lkml.kernel.org/r/20181127165329.GA29728@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make the scheduler's 'sched_smt_present' static key globaly available, so
it can be used in the x86 speculation control code.
Provide a query function and a stub for the CONFIG_SMP=n case.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Casey Schaufler <casey.schaufler@intel.com>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Waiman Long <longman9394@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Dave Stewart <david.c.stewart@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181125185004.430168326@linutronix.de
Currently the 'sched_smt_present' static key is enabled when at CPU bringup
SMT topology is observed, but it is never disabled. However there is demand
to also disable the key when the topology changes such that there is no SMT
present anymore.
Implement this by making the key count the number of cores that have SMT
enabled.
In particular, the SMT topology bits are set before interrrupts are enabled
and similarly, are cleared after interrupts are disabled for the last time
and the CPU dies.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Casey Schaufler <casey.schaufler@intel.com>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Waiman Long <longman9394@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Dave Stewart <david.c.stewart@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181125185004.246110444@linutronix.de
Now that synchronize_rcu() waits for preempt-disable regions of code
as well as RCU read-side critical sections, synchronize_sched() can be
replaced by synchronize_rcu(). This commit therefore makes this change.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Merge misc fixes from Andrew Morton:
"16 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
mm/memblock.c: fix a typo in __next_mem_pfn_range() comments
mm, page_alloc: check for max order in hot path
scripts/spdxcheck.py: make python3 compliant
tmpfs: make lseek(SEEK_DATA/SEK_HOLE) return ENXIO with a negative offset
lib/ubsan.c: don't mark __ubsan_handle_builtin_unreachable as noreturn
mm/vmstat.c: fix NUMA statistics updates
mm/gup.c: fix follow_page_mask() kerneldoc comment
ocfs2: free up write context when direct IO failed
scripts/faddr2line: fix location of start_kernel in comment
mm: don't reclaim inodes with many attached pages
mm, memory_hotplug: check zone_movable in has_unmovable_pages
mm/swapfile.c: use kvzalloc for swap_info_struct allocation
MAINTAINERS: update OMAP MMC entry
hugetlbfs: fix kernel BUG at fs/hugetlbfs/inode.c:444!
kernel/sched/psi.c: simplify cgroup_move_task()
z3fold: fix possible reclaim races
Pull scheduler fix from Ingo Molnar:
"Fix an exec() related scalability/performance regression, which was
caused by incorrectly calculating load and migrating tasks on exec()
when they shouldn't be"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Fix cpu_util_wake() for 'execl' type workloads
The existing code triggered an invalid warning about 'rq' possibly being
used uninitialized. Instead of doing the silly warning suppression by
initializa it to NULL, refactor the code to bail out early instead.
Warning was:
kernel/sched/psi.c: In function `cgroup_move_task':
kernel/sched/psi.c:639:13: warning: `rq' may be used uninitialized in this function [-Wmaybe-uninitialized]
Link: http://lkml.kernel.org/r/20181103183339.8669-1-olof@lixom.net
Fixes: 2ce7135adc ("psi: cgroup support")
Signed-off-by: Olof Johansson <olof@lixom.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is no point in keeping the conditional statement of the #if block
outside of the #ifdef block, while all of its body is contained within
the #ifdef block.
Move the conditional statement under the #ifdef block as well.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/78cbd78a615d6f9fdcd3327f1ead68470f92593e.1541482935.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The variables are local to the source and do not
need to be in global scope, so make them static.
Signed-off-by: Muchun Song <smuchun@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181110075202.61172-1-smuchun@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We already have task_has_rt_policy() and task_has_dl_policy() helpers,
create task_has_idle_policy() as well and update sched core to start
using it.
While at it, use task_has_dl_policy() at one more place.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/ce3915d5b490fc81af926a3b6bfb775e7188e005.1541416894.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The following pattern:
var -= min_t(typeof(var), var, val);
is used multiple times in fair.c.
The existing sub_positive() already captures that pattern, but it also
adds an explicit load-store to properly support lockless observations.
In other cases the pattern above is used to update local, and/or not
concurrently accessed, variables.
Let's add a simpler version of sub_positive(), targeted at local variables
updates, which gives the same readability benefits at calling sites,
without enforcing {READ,WRITE}_ONCE() barriers.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/lkml/20181031184527.GA3178@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The _task_util_est() is mainly used to add/remove the task contribution
to/from the rq's estimated utilization at task enqueue/dequeue time.
In both cases we ensure the UTIL_AVG_UNCHANGED flag is set to keep
consistency between enqueue and dequeue time while still being
transparent to update_load_avg calls which will eventually reset the
flag.
Let's move the flag forcing within _task_util_est() itself so that we
can simplify calling code by hiding that estimated utilization
implementation detail into one of its internal functions.
This will affect also the "public" API task_util_est() but we know that
the flag will (eventually) impact just on the LSB of the estimated
utilization, thus it's certainly acceptable.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/20181105145400.935-3-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A ~10% regression has been reported for UnixBench's execl throughput
test by Aaron Lu and Ye Xiaolong:
https://lkml.org/lkml/2018/10/30/765
That test is pretty simple, it does a "recursive" execve() syscall on the
same binary. Starting from the syscall, this sequence is possible:
do_execve()
do_execveat_common()
__do_execve_file()
sched_exec()
select_task_rq_fair() <==| Task already enqueued
find_idlest_cpu()
find_idlest_group()
capacity_spare_wake() <==| Functions not called from
cpu_util_wake() | the wakeup path
which means we can end up calling cpu_util_wake() not only from the
"wakeup path", as its name would suggest. Indeed, the task doing an
execve() syscall is already enqueued on the CPU we want to get the
cpu_util_wake() for.
The estimated utilization for a CPU computed in cpu_util_wake() was
written under the assumption that function can be called only from the
wakeup path. If instead the task is already enqueued, we end up with a
utilization which does not remove the current task's contribution from
the estimated utilization of the CPU.
This will wrongly assume a reduced spare capacity on the current CPU and
increase the chances to migrate the task on execve.
The regression is tracked down to:
commit d519329f72 ("sched/fair: Update util_est only on util_avg updates")
because in that patch we turn on by default the UTIL_EST sched feature.
However, the real issue is introduced by:
commit f9be3e5961 ("sched/fair: Use util_est in LB and WU paths")
Let's fix this by ensuring to always discount the task estimated
utilization from the CPU's estimated utilization when the task is also
the current one. The same benchmark of the bug report, executed on a
dual socket 40 CPUs Intel(R) Xeon(R) CPU E5-2690 v2 @ 3.00GHz machine,
reports these "Execl Throughput" figures (higher the better):
mainline : 48136.5 lps
mainline+fix : 55376.5 lps
which correspond to a 15% speedup.
Moreover, since {cpu_util,capacity_spare}_wake() are not really only
used from the wakeup path, let's remove this ambiguity by using a better
matching name: {cpu_util,capacity_spare}_without().
Since we are at that, let's also improve the existing documentation.
Reported-by: Aaron Lu <aaron.lu@intel.com>
Reported-by: Ye Xiaolong <xiaolong.ye@intel.com>
Tested-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Fixes: f9be3e5961 (sched/fair: Use util_est in LB and WU paths)
Link: https://lore.kernel.org/lkml/20181025093100.GB13236@e110439-lin/
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler fixes from Thomas Gleixner:
"Two small scheduler fixes:
- Take hotplug lock in sched_init_smp(). Technically not really
required, but lockdep will complain other.
- Trivial comment fix in sched/fair"
* 'sched/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Fix a comment in task_numa_fault()
sched/core: Take the hotplug lock in sched_init_smp()
Now that synchronize_rcu() waits for preempt-disable regions of code
as well as RCU read-side critical sections, the synchronize_sched()
in sys_membarrier() can be replaced by synchronize_rcu(). This commit
therefore makes this change.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Now that synchronize_rcu() waits for both RCU read-side critical
sections and preempt-disabled regions of code, the sole caller of
synchronize_rcu_mult() can be replaced by synchronize_rcu().
This patch makes this change and removes synchronize_rcu_mult().
Note that _wait_rcu_gp() still supports synchronize_rcu_mult(),
and thus might be simplified in the future to take only take
a single call_rcu() function rather than the current list of them.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Pull scheduler fixes from Ingo Molnar:
"A memory (under-)allocation fix and a comment fix"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/topology: Fix off by one bug
sched/rt: Update comment in pick_next_task_rt()
When we pick the next task, we will do the following for the task:
1) p->se.exec_start = rq_clock_task(rq);
2) dequeue_pushable(_dl)_task(rq, p);
When we call set_curr_task(), we also need to do the same thing
above. In rt.c, the code at 1) is in the _pick_next_task_rt()
and the code at 2) is in the pick_next_task_rt(). If we put two
operations in one function, maybe better. So, we introduce a new
function set_next_task(), which is responsible for doing the above.
By introducing the function we can get rid of calling the
dequeue_pushable(_dl)_task() directly(We can call set_next_task())
in pick_next_task() and have better code readability and reuse.
In set_curr_task_rt(), we also can call set_next_task().
Do this things such that we end up with:
static struct task_struct *pick_next_task(struct rq *rq,
struct task_struct *prev,
struct rq_flags *rf)
{
/* do something else ... */
put_prev_task(rq, prev);
/* pick next task p */
set_next_task(rq, p);
/* do something else ... */
}
put_prev_task() can match set_next_task(), which can make the
code more readable.
Signed-off-by: Muchun Song <smuchun@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181026131743.21786-1-smuchun@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When load_balance() fails to move some load because of task affinity,
we end up increasing sd->balance_interval to delay the next periodic
balance in the hopes that next time we look, that annoying pinned
task(s) will be gone.
However, idle_balance() pays no attention to sd->balance_interval, yet
it will still lead to an increase in balance_interval in case of
pinned tasks.
If we're going through several newidle balances (e.g. we have a
periodic task), this can lead to a huge increase of the
balance_interval in a very small amount of time.
To prevent that, don't increase the balance interval when going
through a newidle balance.
This is a similar approach to what is done in commit 58b26c4c02
("sched: Increment cache_nice_tries only on periodic lb"), where we
disregard newidle balance and rely on periodic balance for more stable
results.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: patrick.bellasi@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1537974727-30788-2-git-send-email-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The alignment of the condition is off, clean that up.
Also, logical operators have lower precedence than bitwise/relational
operators, so remove one layer of parentheses to make the condition a
bit simpler to follow.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: patrick.bellasi@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1537974727-30788-1-git-send-email-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When running on linux-next (8c60c36d0b8c ("Add linux-next specific files
for 20181019")) + CONFIG_PROVE_LOCKING=y on a big.LITTLE system (e.g.
Juno or HiKey960), we get the following report:
[ 0.748225] Call trace:
[ 0.750685] lockdep_assert_cpus_held+0x30/0x40
[ 0.755236] static_key_enable_cpuslocked+0x20/0xc8
[ 0.760137] build_sched_domains+0x1034/0x1108
[ 0.764601] sched_init_domains+0x68/0x90
[ 0.768628] sched_init_smp+0x30/0x80
[ 0.772309] kernel_init_freeable+0x278/0x51c
[ 0.776685] kernel_init+0x10/0x108
[ 0.780190] ret_from_fork+0x10/0x18
The static_key in question is 'sched_asym_cpucapacity' introduced by
commit:
df054e8445 ("sched/topology: Add static_key for asymmetric CPU capacity optimizations")
In this particular case, we enable it because smp_prepare_cpus() will
end up fetching the capacity-dmips-mhz entry from the devicetree,
so we already have some asymmetry detected when entering sched_init_smp().
This didn't get detected in tip/sched/core because we were missing:
commit cb538267ea ("jump_label/lockdep: Assert we hold the hotplug lock for _cpuslocked() operations")
Calls to build_sched_domains() post sched_init_smp() will hold the
hotplug lock, it just so happens that this very first call is a
special case. As stated by a comment in sched_init_smp(), "There's no
userspace yet to cause hotplug operations" so this is a harmless
warning.
However, to both respect the semantics of underlying
callees and make lockdep happy, take the hotplug lock in
sched_init_smp(). This also satisfies the comment atop
sched_init_domains() that says "Callers must hold the hotplug lock".
Reported-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: quentin.perret@arm.com
Link: http://lkml.kernel.org/r/1540301851-3048-1-git-send-email-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With the addition of the NUMA identity level, we increased @level by
one and will run off the end of the array in the distance sort loop.
Fixed: 051f3ca02e ("sched/topology: Introduce NUMA identity node sched domain")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
- Fix build regression in the intel_pstate driver that doesn't
build without CONFIG_ACPI after recent changes (Dominik Brodowski).
- One of the heuristics in the menu cpuidle governor is based on a
function returning 0 most of the time, so drop it and clean up
the scheduler code related to it (Daniel Lezcano).
- Prevent the arm_big_little cpufreq driver from being used on ARM64
which is not suitable for it and drop the arm_big_little_dt driver
that is not used any more (Sudeep Holla).
- Prevent the hung task watchdog from triggering during resume from
system-wide sleep states by disabling it before freezing tasks and
enabling it again after they have been thawed (Vitaly Kuznetsov).
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2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=/bnR
-----END PGP SIGNATURE-----
Merge tag 'pm-4.20-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management updates from Rafael Wysocki:
"These remove a questionable heuristic from the menu cpuidle governor,
fix a recent build regression in the intel_pstate driver, clean up ARM
big-Little support in cpufreq and fix up hung task watchdog's
interaction with system-wide power management transitions.
Specifics:
- Fix build regression in the intel_pstate driver that doesn't build
without CONFIG_ACPI after recent changes (Dominik Brodowski).
- One of the heuristics in the menu cpuidle governor is based on a
function returning 0 most of the time, so drop it and clean up the
scheduler code related to it (Daniel Lezcano).
- Prevent the arm_big_little cpufreq driver from being used on ARM64
which is not suitable for it and drop the arm_big_little_dt driver
that is not used any more (Sudeep Holla).
- Prevent the hung task watchdog from triggering during resume from
system-wide sleep states by disabling it before freezing tasks and
enabling it again after they have been thawed (Vitaly Kuznetsov)"
* tag 'pm-4.20-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
kernel: hung_task.c: disable on suspend
cpufreq: remove unused arm_big_little_dt driver
cpufreq: drop ARM_BIG_LITTLE_CPUFREQ support for ARM64
cpufreq: intel_pstate: Fix compilation for !CONFIG_ACPI
cpuidle: menu: Remove get_loadavg() from the performance multiplier
sched: Factor out nr_iowait and nr_iowait_cpu
Commit:
f4ebcbc0d7 ("sched/rt: Substract number of tasks of throttled queues from rq->nr_running")
added a new rt_rq->rt_queued field, which is used to indicate the status of
rq->rt enqueue or dequeue. So, the ->rt_nr_running check was removed and we
now check ->rt_queued instead.
Fix the comment in pick_next_task_rt() as well, which was still referencing
the old logic.
Signed-off-by: Muchun Song <smuchun@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181027030517.23292-1-smuchun@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On a system that executes multiple cgrouped jobs and independent
workloads, we don't just care about the health of the overall system, but
also that of individual jobs, so that we can ensure individual job health,
fairness between jobs, or prioritize some jobs over others.
This patch implements pressure stall tracking for cgroups. In kernels
with CONFIG_PSI=y, cgroup2 groups will have cpu.pressure, memory.pressure,
and io.pressure files that track aggregate pressure stall times for only
the tasks inside the cgroup.
Link: http://lkml.kernel.org/r/20180828172258.3185-10-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When systems are overcommitted and resources become contended, it's hard
to tell exactly the impact this has on workload productivity, or how close
the system is to lockups and OOM kills. In particular, when machines work
multiple jobs concurrently, the impact of overcommit in terms of latency
and throughput on the individual job can be enormous.
In order to maximize hardware utilization without sacrificing individual
job health or risk complete machine lockups, this patch implements a way
to quantify resource pressure in the system.
A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that
expose the percentage of time the system is stalled on CPU, memory, or IO,
respectively. Stall states are aggregate versions of the per-task delay
accounting delays:
cpu: some tasks are runnable but not executing on a CPU
memory: tasks are reclaiming, or waiting for swapin or thrashing cache
io: tasks are waiting for io completions
These percentages of walltime can be thought of as pressure percentages,
and they give a general sense of system health and productivity loss
incurred by resource overcommit. They can also indicate when the system
is approaching lockup scenarios and OOMs.
To do this, psi keeps track of the task states associated with each CPU
and samples the time they spend in stall states. Every 2 seconds, the
samples are averaged across CPUs - weighted by the CPUs' non-idle time to
eliminate artifacts from unused CPUs - and translated into percentages of
walltime. A running average of those percentages is maintained over 10s,
1m, and 5m periods (similar to the loadaverage).
[hannes@cmpxchg.org: doc fixlet, per Randy]
Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org
[hannes@cmpxchg.org: code optimization]
Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org
[hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter]
Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org
[hannes@cmpxchg.org: fix build]
Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_sched_yield() disables IRQs, looks up this_rq() and locks it. The next
patch is adding another site with the same pattern, so provide a
convenience function for it.
Link: http://lkml.kernel.org/r/20180828172258.3185-8-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/sched/sched.h includes "stats.h" half-way through the file. The
next patch introduces users of sched.h's rq locking functions and
update_rq_clock() in kernel/sched/stats.h. Move those definitions up in
the file so they are available in stats.h.
Link: http://lkml.kernel.org/r/20180828172258.3185-7-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's going to be used in a later patch. Keep the churn separate.
Link: http://lkml.kernel.org/r/20180828172258.3185-6-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are several definitions of those functions/macros in places that
mess with fixed-point load averages. Provide an official version.
[akpm@linux-foundation.org: fix missed conversion in block/blk-iolatency.c]
Link: http://lkml.kernel.org/r/20180828172258.3185-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull timekeeping updates from Thomas Gleixner:
"The timers and timekeeping departement provides:
- Another large y2038 update with further preparations for providing
the y2038 safe timespecs closer to the syscalls.
- An overhaul of the SHCMT clocksource driver
- SPDX license identifier updates
- Small cleanups and fixes all over the place"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
tick/sched : Remove redundant cpu_online() check
clocksource/drivers/dw_apb: Add reset control
clocksource: Remove obsolete CLOCKSOURCE_OF_DECLARE
clocksource/drivers: Unify the names to timer-* format
clocksource/drivers/sh_cmt: Add R-Car gen3 support
dt-bindings: timer: renesas: cmt: document R-Car gen3 support
clocksource/drivers/sh_cmt: Properly line-wrap sh_cmt_of_table[] initializer
clocksource/drivers/sh_cmt: Fix clocksource width for 32-bit machines
clocksource/drivers/sh_cmt: Fixup for 64-bit machines
clocksource/drivers/sh_tmu: Convert to SPDX identifiers
clocksource/drivers/sh_mtu2: Convert to SPDX identifiers
clocksource/drivers/sh_cmt: Convert to SPDX identifiers
clocksource/drivers/renesas-ostm: Convert to SPDX identifiers
clocksource: Convert to using %pOFn instead of device_node.name
tick/broadcast: Remove redundant check
RISC-V: Request newstat syscalls
y2038: signal: Change rt_sigtimedwait to use __kernel_timespec
y2038: socket: Change recvmmsg to use __kernel_timespec
y2038: sched: Change sched_rr_get_interval to use __kernel_timespec
y2038: utimes: Rework #ifdef guards for compat syscalls
...
The function get_loadavg() returns almost always zero. To be more
precise, statistically speaking for a total of 1023379 times passing
in the function, the load is equal to zero 1020728 times, greater than
100, 610 times, the remaining is between 0 and 5.
In 2011, the get_loadavg() was removed from the Android tree because
of the above [1]. At this time, the load was:
unsigned long this_cpu_load(void)
{
struct rq *this = this_rq();
return this->cpu_load[0];
}
In 2014, the code was changed by commit 372ba8cb46 (cpuidle: menu: Lookup CPU
runqueues less) and the load is:
void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
{
struct rq *rq = this_rq();
*nr_waiters = atomic_read(&rq->nr_iowait);
*load = rq->load.weight;
}
with the same result.
Both measurements show using the load in this code path does no matter
anymore. Removing it.
[1] 4dedd9f124
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The function nr_iowait_cpu() can be used directly by nr_iowait() instead
of duplicating code.
Call nr_iowait_cpu() from nr_iowait()
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Pull x86 mm updates from Ingo Molnar:
"Lots of changes in this cycle:
- Lots of CPA (change page attribute) optimizations and related
cleanups (Thomas Gleixner, Peter Zijstra)
- Make lazy TLB mode even lazier (Rik van Riel)
- Fault handler cleanups and improvements (Dave Hansen)
- kdump, vmcore: Enable kdumping encrypted memory with AMD SME
enabled (Lianbo Jiang)
- Clean up VM layout documentation (Baoquan He, Ingo Molnar)
- ... plus misc other fixes and enhancements"
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits)
x86/stackprotector: Remove the call to boot_init_stack_canary() from cpu_startup_entry()
x86/mm: Kill stray kernel fault handling comment
x86/mm: Do not warn about PCI BIOS W+X mappings
resource: Clean it up a bit
resource: Fix find_next_iomem_res() iteration issue
resource: Include resource end in walk_*() interfaces
x86/kexec: Correct KEXEC_BACKUP_SRC_END off-by-one error
x86/mm: Remove spurious fault pkey check
x86/mm/vsyscall: Consider vsyscall page part of user address space
x86/mm: Add vsyscall address helper
x86/mm: Fix exception table comments
x86/mm: Add clarifying comments for user addr space
x86/mm: Break out user address space handling
x86/mm: Break out kernel address space handling
x86/mm: Clarify hardware vs. software "error_code"
x86/mm/tlb: Make lazy TLB mode lazier
x86/mm/tlb: Add freed_tables element to flush_tlb_info
x86/mm/tlb: Add freed_tables argument to flush_tlb_mm_range
smp,cpumask: introduce on_each_cpu_cond_mask
smp: use __cpumask_set_cpu in on_each_cpu_cond
...
Pull scheduler updates from Ingo Molnar:
"The main changes are:
- Migrate CPU-intense 'misfit' tasks on asymmetric capacity systems,
to better utilize (much) faster 'big core' CPUs. (Morten Rasmussen,
Valentin Schneider)
- Topology handling improvements, in particular when CPU capacity
changes and related load-balancing fixes/improvements (Morten
Rasmussen)
- ... plus misc other improvements, fixes and updates"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (28 commits)
sched/completions/Documentation: Add recommendation for dynamic and ONSTACK completions
sched/completions/Documentation: Clean up the document some more
sched/completions/Documentation: Fix a couple of punctuation nits
cpu/SMT: State SMT is disabled even with nosmt and without "=force"
sched/core: Fix comment regarding nr_iowait_cpu() and get_iowait_load()
sched/fair: Remove setting task's se->runnable_weight during PELT update
sched/fair: Disable LB_BIAS by default
sched/pelt: Fix warning and clean up IRQ PELT config
sched/topology: Make local variables static
sched/debug: Use symbolic names for task state constants
sched/numa: Remove unused numa_stats::nr_running field
sched/numa: Remove unused code from update_numa_stats()
sched/debug: Explicitly cast sched_feat() to bool
sched/core: Disable SD_PREFER_SIBLING on asymmetric CPU capacity domains
sched/fair: Don't move tasks to lower capacity CPUs unless necessary
sched/fair: Set rq->rd->overload when misfit
sched/fair: Wrap rq->rd->overload accesses with READ/WRITE_ONCE()
sched/core: Change root_domain->overload type to int
sched/fair: Change 'prefer_sibling' type to bool
sched/fair: Kick nohz balance if rq->misfit_task_load
...
The following commit:
d7880812b3 ("idle: Add the stack canary init to cpu_startup_entry()")
... added an x86 specific boot_init_stack_canary() call to the generic
cpu_startup_entry() as a temporary hack, with the intention to remove
the #ifdef CONFIG_X86 later.
More than 5 years later let's finally realize that plan! :-)
While implementing stack protector support for PowerPC, we found
that calling boot_init_stack_canary() is also needed for PowerPC
which uses per task (TLS) stack canary like the X86.
However, calling boot_init_stack_canary() would break architectures
using a global stack canary (ARM, SH, MIPS and XTENSA).
Instead of modifying the #ifdef CONFIG_X86 to an even messier:
#if defined(CONFIG_X86) || defined(CONFIG_PPC)
PowerPC implemented the call to boot_init_stack_canary() in the function
calling cpu_startup_entry().
Let's try the same cleanup on the x86 side as well.
On x86 we have two functions calling cpu_startup_entry():
- start_secondary()
- cpu_bringup_and_idle()
start_secondary() already calls boot_init_stack_canary(), so
it's good, and this patch adds the call to boot_init_stack_canary()
in cpu_bringup_and_idle().
I.e. now x86 catches up to the rest of the world and the ugly init
sequence in init/main.c can be removed from cpu_startup_entry().
As a final benefit we can also remove the <linux/stackprotector.h>
dependency from <linux/sched.h>.
[ mingo: Improved the changelog a bit, added language explaining x86 borkage and sched.h change. ]
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20181020072649.5B59310483E@pc16082vm.idsi0.si.c-s.fr
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The comment and the code around the update_min_vruntime() call in
dequeue_entity() are not in agreement.
From commit:
b60205c7c5 ("sched/fair: Fix min_vruntime tracking")
I think that we want to update min_vruntime when a task is sleeping/migrating.
So, the check is inverted there - fix it.
Signed-off-by: Song Muchun <smuchun@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: b60205c7c5 ("sched/fair: Fix min_vruntime tracking")
Link: http://lkml.kernel.org/r/20181014112612.2614-1-smuchun@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With a very low cpu.cfs_quota_us setting, such as the minimum of 1000,
distribute_cfs_runtime may not empty the throttled_list before it runs
out of runtime to distribute. In that case, due to the change from
c06f04c704 to put throttled entries at the head of the list, later entries
on the list will starve. Essentially, the same X processes will get pulled
off the list, given CPU time and then, when expired, get put back on the
head of the list where distribute_cfs_runtime will give runtime to the same
set of processes leaving the rest.
Fix the issue by setting a bit in struct cfs_bandwidth when
distribute_cfs_runtime is running, so that the code in throttle_cfs_rq can
decide to put the throttled entry on the tail or the head of the list. The
bit is set/cleared by the callers of distribute_cfs_runtime while they hold
cfs_bandwidth->lock.
This is easy to reproduce with a handful of CPU consumers. I use 'crash' on
the live system. In some cases you can simply look at the throttled list and
see the later entries are not changing:
crash> list cfs_rq.throttled_list -H 0xffff90b54f6ade40 -s cfs_rq.runtime_remaining | paste - - | awk '{print $1" "$4}' | pr -t -n3
1 ffff90b56cb2d200 -976050
2 ffff90b56cb2cc00 -484925
3 ffff90b56cb2bc00 -658814
4 ffff90b56cb2ba00 -275365
5 ffff90b166a45600 -135138
6 ffff90b56cb2da00 -282505
7 ffff90b56cb2e000 -148065
8 ffff90b56cb2fa00 -872591
9 ffff90b56cb2c000 -84687
10 ffff90b56cb2f000 -87237
11 ffff90b166a40a00 -164582
crash> list cfs_rq.throttled_list -H 0xffff90b54f6ade40 -s cfs_rq.runtime_remaining | paste - - | awk '{print $1" "$4}' | pr -t -n3
1 ffff90b56cb2d200 -994147
2 ffff90b56cb2cc00 -306051
3 ffff90b56cb2bc00 -961321
4 ffff90b56cb2ba00 -24490
5 ffff90b166a45600 -135138
6 ffff90b56cb2da00 -282505
7 ffff90b56cb2e000 -148065
8 ffff90b56cb2fa00 -872591
9 ffff90b56cb2c000 -84687
10 ffff90b56cb2f000 -87237
11 ffff90b166a40a00 -164582
Sometimes it is easier to see by finding a process getting starved and looking
at the sched_info:
crash> task ffff8eb765994500 sched_info
PID: 7800 TASK: ffff8eb765994500 CPU: 16 COMMAND: "cputest"
sched_info = {
pcount = 8,
run_delay = 697094208,
last_arrival = 240260125039,
last_queued = 240260327513
},
crash> task ffff8eb765994500 sched_info
PID: 7800 TASK: ffff8eb765994500 CPU: 16 COMMAND: "cputest"
sched_info = {
pcount = 8,
run_delay = 697094208,
last_arrival = 240260125039,
last_queued = 240260327513
},
Signed-off-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: c06f04c704 ("sched: Fix potential near-infinite distribute_cfs_runtime() loop")
Link: http://lkml.kernel.org/r/20181008143639.GA4019@pauld.bos.csb
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The comment related to nr_iowait_cpu() and get_iowait_load() confuses
cpufreq with cpuidle and is not very useful for this reason, so fix it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux PM <linux-pm@vger.kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: e33a9bba85 "sched/core: move IO scheduling accounting from io_schedule_timeout() into scheduler"
Link: http://lkml.kernel.org/r/3803514.xkx7zY50tF@aspire.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Automatic NUMA Balancing uses a multi-stage pass to decide whether a page
should migrate to a local node. This filter avoids excessive ping-ponging
if a page is shared or used by threads that migrate cross-node frequently.
Threads inherit both page tables and the preferred node ID from the
parent. This means that threads can trigger hinting faults earlier than
a new task which delays scanning for a number of seconds. As it can be
load balanced very early in its lifetime there can be an unnecessary delay
before it starts migrating thread-local data. This patch migrates private
pages faster early in the lifetime of a thread using the sequence counter
as an identifier of new tasks.
With this patch applied, STREAM performance is the same as 4.17 even though
processes are not spread cross-node prematurely. Other workloads showed
a mix of minor gains and losses. This is somewhat expected most workloads
are not very sensitive to the starting conditions of a process.
4.19.0-rc5 4.19.0-rc5 4.17.0
numab-v1r1 fastmigrate-v1r1 vanilla
MB/sec copy 43298.52 ( 0.00%) 47335.46 ( 9.32%) 47219.24 ( 9.06%)
MB/sec scale 30115.06 ( 0.00%) 32568.12 ( 8.15%) 32527.56 ( 8.01%)
MB/sec add 32825.12 ( 0.00%) 36078.94 ( 9.91%) 35928.02 ( 9.45%)
MB/sec triad 32549.52 ( 0.00%) 35935.94 ( 10.40%) 35969.88 ( 10.51%)
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jirka Hladky <jhladky@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux-MM <linux-mm@kvack.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181001100525.29789-3-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A CFS (SCHED_OTHER, SCHED_BATCH or SCHED_IDLE policy) task's
se->runnable_weight must always be in sync with its se->load.weight.
se->runnable_weight is set to se->load.weight when the task is
forked (init_entity_runnable_average()) or reniced (reweight_entity()).
There are two cases in set_load_weight() which since they currently only
set se->load.weight could lead to a situation in which se->load.weight
is different to se->runnable_weight for a CFS task:
(1) A task switches to SCHED_IDLE.
(2) A SCHED_FIFO, SCHED_RR or SCHED_DEADLINE task which has been reniced
(during which only its static priority gets set) switches to
SCHED_OTHER or SCHED_BATCH.
Set se->runnable_weight to se->load.weight in these two cases to prevent
this. This eliminates the need to explicitly set it to se->load.weight
during PELT updates in the CFS scheduler fastpath.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/20180803140538.1178-1-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
LB_BIAS allows the adjustment on how conservative load should be
balanced.
The rq->cpu_load[idx] array is used for this functionality. It contains
weighted CPU load decayed average values over different intervals
(idx = 1..4). Idx = 0 is the weighted CPU load itself.
The values are updated during scheduler_tick, before idle balance and at
nohz exit.
There are 5 different types of idx's per sched domain (sd). Each of them
is used to index into the rq->cpu_load[idx] array in a specific scenario
(busy, idle and newidle for load balancing, forkexec for wake-up
slow-path load balancing and wake for affine wakeup based on weight).
Only the sd idx's for busy and idle load balancing are set to 2,3 or 1,2
respectively. All the other sd idx's are set to 0.
Conservative load balancing is achieved for sd idx's >= 1 by using the
min/max (source_load()/target_load()) value between the current weighted
CPU load and the rq->cpu_load[sd idx -1] for the busiest(idlest)/local
CPU load in load balancing or vice versa in the wake-up slow-path load
balancing.
There is no conservative balancing for sd idx = 0 since only current
weighted CPU load is used in this case.
It is very likely that LB_BIAS' influence on load balancing can be
neglected (see test results below). This is further supported by:
(1) Weighted CPU load today is by itself a decayed average value (PELT)
(cfs_rq->avg->runnable_load_avg) and not the instantaneous load
(rq->load.weight) it was when LB_BIAS was introduced.
(2) Sd imbalance_pct is used for CPU_NEWLY_IDLE and CPU_NOT_IDLE (relate
to sd's newidle and busy idx) in find_busiest_group() when comparing
busiest and local avg load to make load balancing even more
conservative.
(3) The sd forkexec and newidle idx are always set to 0 so there is no
adjustment on how conservatively load balancing is done here.
(4) Affine wakeup based on weight (wake_affine_weight()) will not be
impacted since the sd wake idx is always set to 0.
Let's disable LB_BIAS by default for a few kernel releases to make sure
that no workload and no scheduler topology is affected. The benefit of
being able to remove the LB_BIAS dependency from source_load() and
target_load() is that the entire rq->cpu_load[idx] code could be removed
in this case.
It is really hard to say if there is no regression w/o testing this with
a lot of different workloads on a lot of different platforms, especially
NUMA machines.
The following 104 LKP (Linux Kernel Performance) tests were run by the
0-Day guys mostly on multi-socket hosts with a larger number of logical
cpus (88, 192).
The base for the test was commit b3dae109fa ("sched/swait: Rename to
exclusive") (tip/sched/core v4.18-rc1).
Only 2 out of the 104 tests had a significant change in one of the
metrics (fsmark/1x-1t-1HDD-btrfs-nfsv4-4M-60G-NoSync-performance +7%
files_per_sec, unixbench/300s-100%-syscall-performance -11% score).
Tests which showed a change in one of the metrics are marked with a '*'
and this change is listed as well.
(a) lkp-bdw-ep3:
88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz 64G
dd-write/10m-1HDD-cfq-btrfs-100dd-performance
fsmark/1x-1t-1HDD-xfs-nfsv4-4M-60G-NoSync-performance
* fsmark/1x-1t-1HDD-btrfs-nfsv4-4M-60G-NoSync-performance
7.50 7% 8.00 ± 6% fsmark.files_per_sec
fsmark/1x-1t-1HDD-btrfs-nfsv4-4M-60G-fsyncBeforeClose-performance
fsmark/1x-1t-1HDD-btrfs-4M-60G-NoSync-performance
fsmark/1x-1t-1HDD-btrfs-4M-60G-fsyncBeforeClose-performance
kbuild/300s-50%-vmlinux_prereq-performance
kbuild/300s-200%-vmlinux_prereq-performance
kbuild/300s-50%-vmlinux_prereq-performance-1HDD-ext4
kbuild/300s-200%-vmlinux_prereq-performance-1HDD-ext4
(b) lkp-skl-4sp1:
192 threads Intel(R) Xeon(R) Platinum 8160 768G
dbench/100%-performance
ebizzy/200%-100x-10s-performance
hackbench/1600%-process-pipe-performance
iperf/300s-cs-localhost-tcp-performance
iperf/300s-cs-localhost-udp-performance
perf-bench-numa-mem/2t-300M-performance
perf-bench-sched-pipe/10000000ops-process-performance
perf-bench-sched-pipe/10000000ops-threads-performance
schbench/2-16-300-30000-30000-performance
tbench/100%-cs-localhost-performance
(c) lkp-bdw-ep6:
88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz 128G
stress-ng/100%-60s-pipe-performance
unixbench/300s-1-whetstone-double-performance
unixbench/300s-1-shell1-performance
unixbench/300s-1-shell8-performance
unixbench/300s-1-pipe-performance
* unixbench/300s-1-context1-performance
312 315 unixbench.score
unixbench/300s-1-spawn-performance
unixbench/300s-1-syscall-performance
unixbench/300s-1-dhry2reg-performance
unixbench/300s-1-fstime-performance
unixbench/300s-1-fsbuffer-performance
unixbench/300s-1-fsdisk-performance
unixbench/300s-100%-whetstone-double-performance
unixbench/300s-100%-shell1-performance
unixbench/300s-100%-shell8-performance
unixbench/300s-100%-pipe-performance
unixbench/300s-100%-context1-performance
unixbench/300s-100%-spawn-performance
* unixbench/300s-100%-syscall-performance
3571 ± 3% -11% 3183 ± 4% unixbench.score
unixbench/300s-100%-dhry2reg-performance
unixbench/300s-100%-fstime-performance
unixbench/300s-100%-fsbuffer-performance
unixbench/300s-100%-fsdisk-performance
unixbench/300s-1-execl-performance
unixbench/300s-100%-execl-performance
* will-it-scale/brk1-performance
365004 360387 will-it-scale.per_thread_ops
* will-it-scale/dup1-performance
432401 437596 will-it-scale.per_thread_ops
will-it-scale/eventfd1-performance
will-it-scale/futex1-performance
will-it-scale/futex2-performance
will-it-scale/futex3-performance
will-it-scale/futex4-performance
will-it-scale/getppid1-performance
will-it-scale/lock1-performance
will-it-scale/lseek1-performance
will-it-scale/lseek2-performance
* will-it-scale/malloc1-performance
47025 45817 will-it-scale.per_thread_ops
77499 76529 will-it-scale.per_process_ops
will-it-scale/malloc2-performance
* will-it-scale/mmap1-performance
123399 120815 will-it-scale.per_thread_ops
152219 149833 will-it-scale.per_process_ops
* will-it-scale/mmap2-performance
107327 104714 will-it-scale.per_thread_ops
136405 133765 will-it-scale.per_process_ops
will-it-scale/open1-performance
* will-it-scale/open2-performance
171570 168805 will-it-scale.per_thread_ops
532644 526202 will-it-scale.per_process_ops
will-it-scale/page_fault1-performance
will-it-scale/page_fault2-performance
will-it-scale/page_fault3-performance
will-it-scale/pipe1-performance
will-it-scale/poll1-performance
* will-it-scale/poll2-performance
176134 172848 will-it-scale.per_thread_ops
281361 275053 will-it-scale.per_process_ops
will-it-scale/posix_semaphore1-performance
will-it-scale/pread1-performance
will-it-scale/pread2-performance
will-it-scale/pread3-performance
will-it-scale/pthread_mutex1-performance
will-it-scale/pthread_mutex2-performance
will-it-scale/pwrite1-performance
will-it-scale/pwrite2-performance
will-it-scale/pwrite3-performance
* will-it-scale/read1-performance
1190563 1174833 will-it-scale.per_thread_ops
* will-it-scale/read2-performance
1105369 1080427 will-it-scale.per_thread_ops
will-it-scale/readseek1-performance
* will-it-scale/readseek2-performance
261818 259040 will-it-scale.per_thread_ops
will-it-scale/readseek3-performance
* will-it-scale/sched_yield-performance
2408059 2382034 will-it-scale.per_thread_ops
will-it-scale/signal1-performance
will-it-scale/unix1-performance
will-it-scale/unlink1-performance
will-it-scale/unlink2-performance
* will-it-scale/write1-performance
976701 961588 will-it-scale.per_thread_ops
* will-it-scale/writeseek1-performance
831898 822448 will-it-scale.per_thread_ops
* will-it-scale/writeseek2-performance
228248 225065 will-it-scale.per_thread_ops
* will-it-scale/writeseek3-performance
226670 224058 will-it-scale.per_thread_ops
will-it-scale/context_switch1-performance
aim7/performance-fork_test-2000
* aim7/performance-brk_test-3000
74869 76676 aim7.jobs-per-min
aim7/performance-disk_cp-3000
aim7/performance-disk_rd-3000
aim7/performance-sieve-3000
aim7/performance-page_test-3000
aim7/performance-creat-clo-3000
aim7/performance-mem_rtns_1-8000
aim7/performance-disk_wrt-8000
aim7/performance-pipe_cpy-8000
aim7/performance-ram_copy-8000
(d) lkp-avoton3:
8 threads Intel(R) Atom(TM) CPU C2750 @ 2.40GHz 16G
netperf/ipv4-900s-200%-cs-localhost-TCP_STREAM-performance
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Li Zhijian <zhijianx.li@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180809135753.21077-1-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Create a config for enabling irq load tracking in the scheduler.
irq load tracking is useful only when irq or paravirtual time is
accounted but it's only possible with SMP for now.
Also use __maybe_unused to remove the compilation warning in
update_rq_clock_task() that has been introduced by:
2e62c4743a ("sched/fair: Remove #ifdefs from scale_rt_capacity()")
Suggested-by: Ingo Molnar <mingo@redhat.com>
Reported-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Reported-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@alien8.de
Cc: dou_liyang@163.com
Fixes: 2e62c4743a ("sched/fair: Remove #ifdefs from scale_rt_capacity()")
Link: http://lkml.kernel.org/r/1537867062-27285-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix the following warnings:
kernel/sched/topology.c:10:15: warning: symbol 'sched_domains_tmpmask' was not declared. Should it be static?
kernel/sched/topology.c:11:15: warning: symbol 'sched_domains_tmpmask2' was not declared. Should it be static?
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1533299852-26941-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
nr_running in struct numa_stats is not used anywhere in the code.
Remove it.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1535548752-4434-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With:
commit 2d4056fafa ("sched/numa: Remove numa_has_capacity()")
the local variables 'smt', 'cpus' and 'capacity' and their results are not used
anymore in numa_has_capacity()
Remove this unused code.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1535548752-4434-2-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
LLVM has a warning that tags expressions like:
if (foo && non-bool-const)
This pattern triggers for CONFIG_SCHED_DEBUG=n where sched_feat() ends
up being whatever bit we select. Avoid the warning with an explicit
cast to bool.
Reported-by: Philipp Klocke <philipp97kl@gmail.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The 'prefer sibling' sched_domain flag is intended to encourage
spreading tasks to sibling sched_domain to take advantage of more caches
and core for SMT systems. It has recently been changed to be on all
non-NUMA topology level. However, spreading across domains with CPU
capacity asymmetry isn't desirable, e.g. spreading from high capacity to
low capacity CPUs even if high capacity CPUs aren't overutilized might
give access to more cache but the CPU will be slower and possibly lead
to worse overall throughput.
To prevent this, we need to remove SD_PREFER_SIBLING on the sched_domain
level immediately below SD_ASYM_CPUCAPACITY.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-13-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When lower capacity CPUs are load balancing and considering to pull
something from a higher capacity group, we should not pull tasks from a
CPU with only one task running as this is guaranteed to impede progress
for that task. If there is more than one task running, load balance in
the higher capacity group would have already made any possible moves to
resolve imbalance and we should make better use of system compute
capacity by moving a task if we still have more than one running.
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-11-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Idle balance is a great opportunity to pull a misfit task. However,
there are scenarios where misfit tasks are present but idle balance is
prevented by the overload flag.
A good example of this is a workload of n identical tasks. Let's suppose
we have a 2+2 Arm big.LITTLE system. We then spawn 4 fairly
CPU-intensive tasks - for the sake of simplicity let's say they are just
CPU hogs, even when running on big CPUs.
They are identical tasks, so on an SMP system they should all end at
(roughly) the same time. However, in our case the LITTLE CPUs are less
performing than the big CPUs, so tasks running on the LITTLEs will have
a longer completion time.
This means that the big CPUs will complete their work earlier, at which
point they should pull the tasks from the LITTLEs. What we want to
happen is summarized as follows:
a,b,c,d are our CPU-hogging tasks _ signifies idling
LITTLE_0 | a a a a _ _
LITTLE_1 | b b b b _ _
---------|-------------
big_0 | c c c c a a
big_1 | d d d d b b
^
^
Tasks end on the big CPUs, idle balance happens
and the misfit tasks are pulled straight away
This however won't happen, because currently the overload flag is only
set when there is any CPU that has more than one runnable task - which
may very well not be the case here if our CPU-hogging workload is all
there is to run.
As such, this commit sets the overload flag in update_sg_lb_stats when
a group is flagged as having a misfit task.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-10-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This variable can be read and set locklessly within update_sd_lb_stats().
As such, READ/WRITE_ONCE() are added to make sure nothing terribly wrong
can happen because of the compiler.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-9-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sizeof(_Bool) is implementation defined, so let's just go with 'int' as
is done for other structures e.g. sched_domain_shared->has_idle_cores.
The local 'overload' variable used in update_sd_lb_stats can remain
bool, as it won't impact any struct layout and can be assigned to the
root_domain field.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-8-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This variable is entirely local to update_sd_lb_stats, so we can
safely change its type and slightly clean up its initialisation.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-7-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There already are a few conditions in nohz_kick_needed() to ensure
a nohz kick is triggered, but they are not enough for some misfit
task scenarios. Excluding asym packing, those are:
- rq->nr_running >=2: Not relevant here because we are running a
misfit task, it needs to be migrated regardless and potentially through
active balance.
- sds->nr_busy_cpus > 1: If there is only the misfit task being run
on a group of low capacity CPUs, this will be evaluated to False.
- rq->cfs.h_nr_running >=1 && check_cpu_capacity(): Not relevant here,
misfit task needs to be migrated regardless of rt/IRQ pressure
As such, this commit adds an rq->misfit_task_load condition to trigger a
nohz kick.
The idea to kick a nohz balance for misfit tasks originally came from
Leo Yan <leo.yan@linaro.org>, and a similar patch was submitted for
the Android Common Kernel - see:
https://lists.linaro.org/pipermail/eas-dev/2016-September/000551.html
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-6-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On asymmetric CPU capacity systems load intensive tasks can end up on
CPUs that don't suit their compute demand. In this scenarios 'misfit'
tasks should be migrated to CPUs with higher compute capacity to ensure
better throughput. group_misfit_task indicates this scenario, but tweaks
to the load-balance code are needed to make the migrations happen.
Misfit balancing only makes sense between a source group of lower
per-CPU capacity and destination group of higher compute capacity.
Otherwise, misfit balancing is ignored. group_misfit_task has lowest
priority so any imbalance due to overload is dealt with first.
The modifications are:
1. Only pick a group containing misfit tasks as the busiest group if the
destination group has higher capacity and has spare capacity.
2. When the busiest group is a 'misfit' group, skip the usual average
load and group capacity checks.
3. Set the imbalance for 'misfit' balancing sufficiently high for a task
to be pulled ignoring average load.
4. Pick the CPU with the highest misfit load as the source CPU.
5. If the misfit task is alone on the source CPU, go for active
balancing.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-5-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The current sg->min_capacity tracks the lowest per-CPU compute capacity
available in the sched_group when rt/irq pressure is taken into account.
Minimum capacity isn't the ideal metric for tracking if a sched_group
needs offloading to another sched_group for some scenarios, e.g. a
sched_group with multiple CPUs if only one is under heavy pressure.
Tracking maximum capacity isn't perfect either but a better choice for
some situations as it indicates that the sched_group definitely compute
capacity constrained either due to rt/irq pressure on all CPUs or
asymmetric CPU capacities (e.g. big.LITTLE).
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-4-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
To maximize throughput in systems with asymmetric CPU capacities (e.g.
ARM big.LITTLE) load-balancing has to consider task and CPU utilization
as well as per-CPU compute capacity when load-balancing in addition to
the current average load based load-balancing policy. Tasks with high
utilization that are scheduled on a lower capacity CPU need to be
identified and migrated to a higher capacity CPU if possible to maximize
throughput.
To implement this additional policy an additional group_type
(load-balance scenario) is added: 'group_misfit_task'. This represents
scenarios where a sched_group has one or more tasks that are not
suitable for its per-CPU capacity. 'group_misfit_task' is only considered
if the system is not overloaded or imbalanced ('group_imbalanced' or
'group_overloaded').
Identifying misfit tasks requires the rq lock to be held. To avoid
taking remote rq locks to examine source sched_groups for misfit tasks,
each CPU is responsible for tracking misfit tasks themselves and update
the rq->misfit_task flag. This means checking task utilization when
tasks are scheduled and on sched_tick.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-3-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The existing asymmetric CPU capacity code should cause minimal overhead
for others. Putting it behind a static_key, it has been done for SMT
optimizations, would make it easier to extend and improve without
causing harm to others moving forward.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: gaku.inami.xh@renesas.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1530699470-29808-2-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The SD_ASYM_CPUCAPACITY sched_domain flag is supposed to mark the
sched_domain in the hierarchy where all CPU capacities are visible for
any CPU's point of view on asymmetric CPU capacity systems. The
scheduler can then take to take capacity asymmetry into account when
balancing at this level. It also serves as an indicator for how wide
task placement heuristics have to search to consider all available CPU
capacities as asymmetric systems might often appear symmetric at
smallest level(s) of the sched_domain hierarchy.
The flag has been around for while but so far only been set by
out-of-tree code in Android kernels. One solution is to let each
architecture provide the flag through a custom sched_domain topology
array and associated mask and flag functions. However,
SD_ASYM_CPUCAPACITY is special in the sense that it depends on the
capacity and presence of all CPUs in the system, i.e. when hotplugging
all CPUs out except those with one particular CPU capacity the flag
should disappear even if the sched_domains don't collapse. Similarly,
the flag is affected by cpusets where load-balancing is turned off.
Detecting when the flags should be set therefore depends not only on
topology information but also the cpuset configuration and hotplug
state. The arch code doesn't have easy access to the cpuset
configuration.
Instead, this patch implements the flag detection in generic code where
cpusets and hotplug state is already taken care of. All the arch is
responsible for is to implement arch_scale_cpu_capacity() and force a
full rebuild of the sched_domain hierarchy if capacities are updated,
e.g. later in the boot process when cpufreq has initialized.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1532093554-30504-2-git-send-email-morten.rasmussen@arm.com
[ Fixed 'CPU' capitalization. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix kernel-doc warning for missing 'flags' parameter description:
../kernel/sched/fair.c:3371: warning: Function parameter or member 'flags' not described in 'attach_entity_load_avg'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: ea14b57e8a ("sched/cpufreq: Provide migration hint")
Link: http://lkml.kernel.org/r/cdda0d42-880d-4229-a9f7-5899c977a063@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It can happen that load_balance() finds a busiest group and then a
busiest rq but the calculated imbalance is in fact 0.
In such situation, detach_tasks() returns immediately and lets the
flag LBF_ALL_PINNED set. The busiest CPU is then wrongly assumed to
have pinned tasks and removed from the load balance mask. then, we
redo a load balance without the busiest CPU. This creates wrong load
balance situation and generates wrong task migration.
If the calculated imbalance is 0, it's useless to try to find a
busiest rq as no task will be migrated and we can return immediately.
This situation can happen with heterogeneous system or smp system when
RT tasks are decreasing the capacity of some CPUs.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: jhugo@codeaurora.org
Link: http://lkml.kernel.org/r/1536306664-29827-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since commit:
523e979d31 ("sched/core: Use PELT for scale_rt_capacity()")
scale_rt_capacity() returns the remaining capacity and not a scale factor
to apply on cpu_capacity_orig. arch_scale_cpu() is directly called by
scale_rt_capacity() so we must take the sched_domain argument.
Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 523e979d31 ("sched/core: Use PELT for scale_rt_capacity()")
Link: http://lkml.kernel.org/r/20180904093626.GA23936@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a task which previously ran on a given CPU is remotely queued to
wake up on that same CPU, there is a period where the task's state is
TASK_WAKING and its vruntime is not normalized. This is not accounted
for in vruntime_normalized() which will cause an error in the task's
vruntime if it is switched from the fair class during this time.
For example if it is boosted to RT priority via rt_mutex_setprio(),
rq->min_vruntime will not be subtracted from the task's vruntime but
it will be added again when the task returns to the fair class. The
task's vruntime will have been erroneously doubled and the effective
priority of the task will be reduced.
Note this will also lead to inflation of all vruntimes since the doubled
vruntime value will become the rq's min_vruntime when other tasks leave
the rq. This leads to repeated doubling of the vruntime and priority
penalty.
Fix this by recognizing a WAKING task's vruntime as normalized only if
sched_remote_wakeup is true. This indicates a migration, in which case
the vruntime would have been normalized in migrate_task_rq_fair().
Based on a similar patch from John Dias <joaodias@google.com>.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Steve Muckle <smuckle@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Redpath <Chris.Redpath@arm.com>
Cc: John Dias <joaodias@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miguel de Dios <migueldedios@google.com>
Cc: Morten Rasmussen <Morten.Rasmussen@arm.com>
Cc: Patrick Bellasi <Patrick.Bellasi@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: kernel-team@android.com
Fixes: b5179ac70d ("sched/fair: Prepare to fix fairness problems on migration")
Link: http://lkml.kernel.org/r/20180831224217.169476-1-smuckle@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
update_blocked_averages() is called to periodiccally decay the stalled load
of idle CPUs and to sync all loads before running load balance.
When cfs rq is idle, it trigs a load balance during pick_next_task_fair()
in order to potentially pull tasks and to use this newly idle CPU. This
load balance happens whereas prev task from another class has not been put
and its utilization updated yet. This may lead to wrongly account running
time as idle time for RT or DL classes.
Test that no RT or DL task is running when updating their utilization in
update_blocked_averages().
We still update RT and DL utilization instead of simply skipping them to
make sure that all metrics are synced when used during load balance.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 371bf42732 ("sched/rt: Add rt_rq utilization tracking")
Fixes: 3727e0e163 ("sched/dl: Add dl_rq utilization tracking")
Link: http://lkml.kernel.org/r/1535728975-22799-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With the following commit:
051f3ca02e ("sched/topology: Introduce NUMA identity node sched domain")
the scheduler introduced a new NUMA level. However this leads to the NUMA topology
on 2 node systems to not be marked as NUMA_DIRECT anymore.
After this commit, it gets reported as NUMA_BACKPLANE, because
sched_domains_numa_level is now 2 on 2 node systems.
Fix this by allowing setting systems that have up to 2 NUMA levels as
NUMA_DIRECT.
While here remove code that assumes that level can be 0.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andre Wild <wild@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Fixes: 051f3ca02e "Introduce NUMA identity node sched domain"
Link: http://lkml.kernel.org/r/1533920419-17410-1-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is a preparation patch for converting sys_sched_rr_get_interval to
work with 64-bit time_t on 32-bit architectures. The 'interval' argument
is changed to struct __kernel_timespec, which will be redefined using
64-bit time_t in the future. The compat version of the system call in
turn is enabled for compilation with CONFIG_COMPAT_32BIT_TIME so
the individual 32-bit architectures can share the handling of the
traditional argument with 64-bit architectures providing it for their
compat mode.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Christoph Hellwig suggested a slightly different path for handling
backwards compatibility with the 32-bit time_t based system calls:
Rather than simply reusing the compat_sys_* entry points on 32-bit
architectures unchanged, we get rid of those entry points and the
compat_time types by renaming them to something that makes more sense
on 32-bit architectures (which don't have a compat mode otherwise),
and then share the entry points under the new name with the 64-bit
architectures that use them for implementing the compatibility.
The following types and interfaces are renamed here, and moved
from linux/compat_time.h to linux/time32.h:
old new
--- ---
compat_time_t old_time32_t
struct compat_timeval struct old_timeval32
struct compat_timespec struct old_timespec32
struct compat_itimerspec struct old_itimerspec32
ns_to_compat_timeval() ns_to_old_timeval32()
get_compat_itimerspec64() get_old_itimerspec32()
put_compat_itimerspec64() put_old_itimerspec32()
compat_get_timespec64() get_old_timespec32()
compat_put_timespec64() put_old_timespec32()
As we already have aliases in place, this patch addresses only the
instances that are relevant to the system call interface in particular,
not those that occur in device drivers and other modules. Those
will get handled separately, while providing the 64-bit version
of the respective interfaces.
I'm not renaming the timex, rusage and itimerval structures, as we are
still debating what the new interface will look like, and whether we
will need a replacement at all.
This also doesn't change the names of the syscall entry points, which can
be done more easily when we actually switch over the 32-bit architectures
to use them, at that point we need to change COMPAT_SYSCALL_DEFINEx to
SYSCALL_DEFINEx with a new name, e.g. with a _time32 suffix.
Suggested-by: Christoph Hellwig <hch@infradead.org>
Link: https://lore.kernel.org/lkml/20180705222110.GA5698@infradead.org/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Merge more updates from Andrew Morton:
- the rest of MM
- procfs updates
- various misc things
- more y2038 fixes
- get_maintainer updates
- lib/ updates
- checkpatch updates
- various epoll updates
- autofs updates
- hfsplus
- some reiserfs work
- fatfs updates
- signal.c cleanups
- ipc/ updates
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (166 commits)
ipc/util.c: update return value of ipc_getref from int to bool
ipc/util.c: further variable name cleanups
ipc: simplify ipc initialization
ipc: get rid of ids->tables_initialized hack
lib/rhashtable: guarantee initial hashtable allocation
lib/rhashtable: simplify bucket_table_alloc()
ipc: drop ipc_lock()
ipc/util.c: correct comment in ipc_obtain_object_check
ipc: rename ipcctl_pre_down_nolock()
ipc/util.c: use ipc_rcu_putref() for failues in ipc_addid()
ipc: reorganize initialization of kern_ipc_perm.seq
ipc: compute kern_ipc_perm.id under the ipc lock
init/Kconfig: remove EXPERT from CHECKPOINT_RESTORE
fs/sysv/inode.c: use ktime_get_real_seconds() for superblock stamp
adfs: use timespec64 for time conversion
kernel/sysctl.c: fix typos in comments
drivers/rapidio/devices/rio_mport_cdev.c: remove redundant pointer md
fork: don't copy inconsistent signal handler state to child
signal: make get_signal() return bool
signal: make sigkill_pending() return bool
...
Better ensure we actually hold the lock using lockdep than just commenting
on it. Due to the various exported _locked interfaces it is far too easy
to get the locking wrong.
Link: http://lkml.kernel.org/r/20171214152344.6880-4-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Make the idle loop handle stopped scheduler tick correctly (Rafael
Wysocki).
- Prevent the menu cpuidle governor from letting CPUs spend too much
time in shallow idle states when it is invoked with scheduler tick
stopped and clean it up somewhat (Rafael Wysocki).
- Avoid invoking the platform firmware to make the platform enter
the ACPI S3 sleep state with suspended PCIe root ports which may
confuse the firmware and cause it to crash (Rafael Wysocki).
- Fix sysfs-related race in the ondemand and conservative cpufreq
governors which may cause the system to crash if the governor
module is removed during an update of CPU frequency limits (Henry
Willard).
- Select SRCU when building the system wakeup framework to avoid a
build issue in it (zhangyi).
- Make the descriptions of ACPI C-states vendor-neutral to avoid
confusion (Prarit Bhargava).
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2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=9GrU
-----END PGP SIGNATURE-----
Merge tag 'pm-4.19-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management updates from Rafael Wysocki:
"These fix the main idle loop and the menu cpuidle governor, clean up
the latter, fix a mistake in the PCI bus type's support for system
suspend and resume, fix the ondemand and conservative cpufreq
governors, address a build issue in the system wakeup framework and
make the ACPI C-states desciptions less confusing.
Specifics:
- Make the idle loop handle stopped scheduler tick correctly (Rafael
Wysocki).
- Prevent the menu cpuidle governor from letting CPUs spend too much
time in shallow idle states when it is invoked with scheduler tick
stopped and clean it up somewhat (Rafael Wysocki).
- Avoid invoking the platform firmware to make the platform enter the
ACPI S3 sleep state with suspended PCIe root ports which may
confuse the firmware and cause it to crash (Rafael Wysocki).
- Fix sysfs-related race in the ondemand and conservative cpufreq
governors which may cause the system to crash if the governor
module is removed during an update of CPU frequency limits (Henry
Willard).
- Select SRCU when building the system wakeup framework to avoid a
build issue in it (zhangyi).
- Make the descriptions of ACPI C-states vendor-neutral to avoid
confusion (Prarit Bhargava)"
* tag 'pm-4.19-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpuidle: menu: Handle stopped tick more aggressively
sched: idle: Avoid retaining the tick when it has been stopped
PCI / ACPI / PM: Resume all bridges on suspend-to-RAM
cpuidle: menu: Update stale polling override comment
cpufreq: governor: Avoid accessing invalid governor_data
x86/ACPI/cstate: Make APCI C1 FFH MWAIT C-state description vendor-neutral
cpuidle: menu: Fix white space
PM / sleep: wakeup: Fix build error caused by missing SRCU support
Pull core signal handling updates from Eric Biederman:
"It was observed that a periodic timer in combination with a
sufficiently expensive fork could prevent fork from every completing.
This contains the changes to remove the need for that restart.
This set of changes is split into several parts:
- The first part makes PIDTYPE_TGID a proper pid type instead
something only for very special cases. The part starts using
PIDTYPE_TGID enough so that in __send_signal where signals are
actually delivered we know if the signal is being sent to a a group
of processes or just a single process.
- With that prep work out of the way the logic in fork is modified so
that fork logically makes signals received while it is running
appear to be received after the fork completes"
* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (22 commits)
signal: Don't send signals to tasks that don't exist
signal: Don't restart fork when signals come in.
fork: Have new threads join on-going signal group stops
fork: Skip setting TIF_SIGPENDING in ptrace_init_task
signal: Add calculate_sigpending()
fork: Unconditionally exit if a fatal signal is pending
fork: Move and describe why the code examines PIDNS_ADDING
signal: Push pid type down into complete_signal.
signal: Push pid type down into __send_signal
signal: Push pid type down into send_signal
signal: Pass pid type into do_send_sig_info
signal: Pass pid type into send_sigio_to_task & send_sigurg_to_task
signal: Pass pid type into group_send_sig_info
signal: Pass pid and pid type into send_sigqueue
posix-timers: Noralize good_sigevent
signal: Use PIDTYPE_TGID to clearly store where file signals will be sent
pid: Implement PIDTYPE_TGID
pids: Move the pgrp and session pid pointers from task_struct to signal_struct
kvm: Don't open code task_pid in kvm_vcpu_ioctl
pids: Compute task_tgid using signal->leader_pid
...
- Restructure of lockdep and latency tracers
This is the biggest change. Joel Fernandes restructured the hooks
from irqs and preemption disabling and enabling. He got rid of
a lot of the preprocessor #ifdef mess that they caused.
He turned both lockdep and the latency tracers to use trace events
inserted in the preempt/irqs disabling paths. But unfortunately,
these started to cause issues in corner cases. Thus, parts of the
code was reverted back to where lockde and the latency tracers
just get called directly (without using the trace events).
But because the original change cleaned up the code very nicely
we kept that, as well as the trace events for preempt and irqs
disabling, but they are limited to not being called in NMIs.
- Have trace events use SRCU for "rcu idle" calls. This was required
for the preempt/irqs off trace events. But it also had to not
allow them to be called in NMI context. Waiting till Paul makes
an NMI safe SRCU API.
- New notrace SRCU API to allow trace events to use SRCU.
- Addition of mcount-nop option support
- SPDX headers replacing GPL templates.
- Various other fixes and clean ups.
- Some fixes are marked for stable, but were not fully tested
before the merge window opened.
-----BEGIN PGP SIGNATURE-----
iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCW3ruhRQccm9zdGVkdEBn
b29kbWlzLm9yZwAKCRAp5XQQmuv6qiM7AP47NhYdSnCFCRUJfrt6PovXmQtuCHt3
c3QMoGGdvzh9YAEAqcSXwh7uLhpHUp1LjMAPkXdZVwNddf4zJQ1zyxQ+EAU=
=vgEr
-----END PGP SIGNATURE-----
Merge tag 'trace-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
- Restructure of lockdep and latency tracers
This is the biggest change. Joel Fernandes restructured the hooks
from irqs and preemption disabling and enabling. He got rid of a lot
of the preprocessor #ifdef mess that they caused.
He turned both lockdep and the latency tracers to use trace events
inserted in the preempt/irqs disabling paths. But unfortunately,
these started to cause issues in corner cases. Thus, parts of the
code was reverted back to where lockdep and the latency tracers just
get called directly (without using the trace events). But because the
original change cleaned up the code very nicely we kept that, as well
as the trace events for preempt and irqs disabling, but they are
limited to not being called in NMIs.
- Have trace events use SRCU for "rcu idle" calls. This was required
for the preempt/irqs off trace events. But it also had to not allow
them to be called in NMI context. Waiting till Paul makes an NMI safe
SRCU API.
- New notrace SRCU API to allow trace events to use SRCU.
- Addition of mcount-nop option support
- SPDX headers replacing GPL templates.
- Various other fixes and clean ups.
- Some fixes are marked for stable, but were not fully tested before
the merge window opened.
* tag 'trace-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits)
tracing: Fix SPDX format headers to use C++ style comments
tracing: Add SPDX License format tags to tracing files
tracing: Add SPDX License format to bpf_trace.c
blktrace: Add SPDX License format header
s390/ftrace: Add -mfentry and -mnop-mcount support
tracing: Add -mcount-nop option support
tracing: Avoid calling cc-option -mrecord-mcount for every Makefile
tracing: Handle CC_FLAGS_FTRACE more accurately
Uprobe: Additional argument arch_uprobe to uprobe_write_opcode()
Uprobes: Simplify uprobe_register() body
tracepoints: Free early tracepoints after RCU is initialized
uprobes: Use synchronize_rcu() not synchronize_sched()
tracing: Fix synchronizing to event changes with tracepoint_synchronize_unregister()
ftrace: Remove unused pointer ftrace_swapper_pid
tracing: More reverting of "tracing: Centralize preemptirq tracepoints and unify their usage"
tracing/irqsoff: Handle preempt_count for different configs
tracing: Partial revert of "tracing: Centralize preemptirq tracepoints and unify their usage"
tracing: irqsoff: Account for additional preempt_disable
trace: Use rcu_dereference_raw for hooks from trace-event subsystem
tracing/kprobes: Fix within_notrace_func() to check only notrace functions
...
If the tick has been stopped already, but the governor has not asked to
stop it (which it can do sometimes), the idle loop should invoke
tick_nohz_idle_stop_tick(), to let tick_nohz_stop_tick() take care
of this case properly.
Fixes: 554c8aa8ec (sched: idle: Select idle state before stopping the tick)
Cc: 4.17+ <stable@vger.kernel.org> # 4.17+
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge L1 Terminal Fault fixes from Thomas Gleixner:
"L1TF, aka L1 Terminal Fault, is yet another speculative hardware
engineering trainwreck. It's a hardware vulnerability which allows
unprivileged speculative access to data which is available in the
Level 1 Data Cache when the page table entry controlling the virtual
address, which is used for the access, has the Present bit cleared or
other reserved bits set.
If an instruction accesses a virtual address for which the relevant
page table entry (PTE) has the Present bit cleared or other reserved
bits set, then speculative execution ignores the invalid PTE and loads
the referenced data if it is present in the Level 1 Data Cache, as if
the page referenced by the address bits in the PTE was still present
and accessible.
While this is a purely speculative mechanism and the instruction will
raise a page fault when it is retired eventually, the pure act of
loading the data and making it available to other speculative
instructions opens up the opportunity for side channel attacks to
unprivileged malicious code, similar to the Meltdown attack.
While Meltdown breaks the user space to kernel space protection, L1TF
allows to attack any physical memory address in the system and the
attack works across all protection domains. It allows an attack of SGX
and also works from inside virtual machines because the speculation
bypasses the extended page table (EPT) protection mechanism.
The assoicated CVEs are: CVE-2018-3615, CVE-2018-3620, CVE-2018-3646
The mitigations provided by this pull request include:
- Host side protection by inverting the upper address bits of a non
present page table entry so the entry points to uncacheable memory.
- Hypervisor protection by flushing L1 Data Cache on VMENTER.
- SMT (HyperThreading) control knobs, which allow to 'turn off' SMT
by offlining the sibling CPU threads. The knobs are available on
the kernel command line and at runtime via sysfs
- Control knobs for the hypervisor mitigation, related to L1D flush
and SMT control. The knobs are available on the kernel command line
and at runtime via sysfs
- Extensive documentation about L1TF including various degrees of
mitigations.
Thanks to all people who have contributed to this in various ways -
patches, review, testing, backporting - and the fruitful, sometimes
heated, but at the end constructive discussions.
There is work in progress to provide other forms of mitigations, which
might be less horrible performance wise for a particular kind of
workloads, but this is not yet ready for consumption due to their
complexity and limitations"
* 'l1tf-final' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (75 commits)
x86/microcode: Allow late microcode loading with SMT disabled
tools headers: Synchronise x86 cpufeatures.h for L1TF additions
x86/mm/kmmio: Make the tracer robust against L1TF
x86/mm/pat: Make set_memory_np() L1TF safe
x86/speculation/l1tf: Make pmd/pud_mknotpresent() invert
x86/speculation/l1tf: Invert all not present mappings
cpu/hotplug: Fix SMT supported evaluation
KVM: VMX: Tell the nested hypervisor to skip L1D flush on vmentry
x86/speculation: Use ARCH_CAPABILITIES to skip L1D flush on vmentry
x86/speculation: Simplify sysfs report of VMX L1TF vulnerability
Documentation/l1tf: Remove Yonah processors from not vulnerable list
x86/KVM/VMX: Don't set l1tf_flush_l1d from vmx_handle_external_intr()
x86/irq: Let interrupt handlers set kvm_cpu_l1tf_flush_l1d
x86: Don't include linux/irq.h from asm/hardirq.h
x86/KVM/VMX: Introduce per-host-cpu analogue of l1tf_flush_l1d
x86/irq: Demote irq_cpustat_t::__softirq_pending to u16
x86/KVM/VMX: Move the l1tf_flush_l1d test to vmx_l1d_flush()
x86/KVM/VMX: Replace 'vmx_l1d_flush_always' with 'vmx_l1d_flush_cond'
x86/KVM/VMX: Don't set l1tf_flush_l1d to true from vmx_l1d_flush()
cpu/hotplug: detect SMT disabled by BIOS
...
Pull x86 timer updates from Thomas Gleixner:
"Early TSC based time stamping to allow better boot time analysis.
This comes with a general cleanup of the TSC calibration code which
grew warts and duct taping over the years and removes 250 lines of
code. Initiated and mostly implemented by Pavel with help from various
folks"
* 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits)
x86/kvmclock: Mark kvm_get_preset_lpj() as __init
x86/tsc: Consolidate init code
sched/clock: Disable interrupts when calling generic_sched_clock_init()
timekeeping: Prevent false warning when persistent clock is not available
sched/clock: Close a hole in sched_clock_init()
x86/tsc: Make use of tsc_calibrate_cpu_early()
x86/tsc: Split native_calibrate_cpu() into early and late parts
sched/clock: Use static key for sched_clock_running
sched/clock: Enable sched clock early
sched/clock: Move sched clock initialization and merge with generic clock
x86/tsc: Use TSC as sched clock early
x86/tsc: Initialize cyc2ns when tsc frequency is determined
x86/tsc: Calibrate tsc only once
ARM/time: Remove read_boot_clock64()
s390/time: Remove read_boot_clock64()
timekeeping: Default boot time offset to local_clock()
timekeeping: Replace read_boot_clock64() with read_persistent_wall_and_boot_offset()
s390/time: Add read_persistent_wall_and_boot_offset()
x86/xen/time: Output xen sched_clock time from 0
x86/xen/time: Initialize pv xen time in init_hypervisor_platform()
...
Pull locking/atomics update from Thomas Gleixner:
"The locking, atomics and memory model brains delivered:
- A larger update to the atomics code which reworks the ordering
barriers, consolidates the atomic primitives, provides the new
atomic64_fetch_add_unless() primitive and cleans up the include
hell.
- Simplify cmpxchg() instrumentation and add instrumentation for
xchg() and cmpxchg_double().
- Updates to the memory model and documentation"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (48 commits)
locking/atomics: Rework ordering barriers
locking/atomics: Instrument cmpxchg_double*()
locking/atomics: Instrument xchg()
locking/atomics: Simplify cmpxchg() instrumentation
locking/atomics/x86: Reduce arch_cmpxchg64*() instrumentation
tools/memory-model: Rename litmus tests to comply to norm7
tools/memory-model/Documentation: Fix typo, smb->smp
sched/Documentation: Update wake_up() & co. memory-barrier guarantees
locking/spinlock, sched/core: Clarify requirements for smp_mb__after_spinlock()
sched/core: Use smp_mb() in wake_woken_function()
tools/memory-model: Add informal LKMM documentation to MAINTAINERS
locking/atomics/Documentation: Describe atomic_set() as a write operation
tools/memory-model: Make scripts executable
tools/memory-model: Remove ACCESS_ONCE() from model
tools/memory-model: Remove ACCESS_ONCE() from recipes
locking/memory-barriers.txt/kokr: Update Korean translation to fix broken DMA vs. MMIO ordering example
MAINTAINERS: Add Daniel Lustig as an LKMM reviewer
tools/memory-model: Fix ISA2+pooncelock+pooncelock+pombonce name
tools/memory-model: Add litmus test for full multicopy atomicity
locking/refcount: Always allow checked forms
...
Add a function calculate_sigpending to test to see if any signals are
pending for a new task immediately following fork. Signals have to
happen either before or after fork. Today our practice is to push
all of the signals to before the fork, but that has the downside that
frequent or periodic signals can make fork take much much longer than
normal or prevent fork from completing entirely.
So we need move signals that we can after the fork to prevent that.
This updates the code to set TIF_SIGPENDING on a new task if there
are signals or other activities that have moved so that they appear
to happen after the fork.
As the code today restarts if it sees any such activity this won't
immediately have an effect, as there will be no reason for it
to set TIF_SIGPENDING immediately after the fork.
Adding calculate_sigpending means the code in fork can safely be
changed to not always restart if a signal is pending.
The new calculate_sigpending function sets sigpending if there
are pending bits in jobctl, pending signals, the freezer needs
to freeze the new task or the live kernel patching framework
need the new thread to take the slow path to userspace.
I have verified that setting TIF_SIGPENDING does make a new process
take the slow path to userspace before it executes it's first userspace
instruction.
I have looked at the callers of signal_wake_up and the code paths
setting TIF_SIGPENDING and I don't see anything else that needs to be
handled. The code probably doesn't need to set TIF_SIGPENDING for the
kernel live patching as it uses a separate thread flag as well. But
at this point it seems safer reuse the recalc_sigpending logic and get
the kernel live patching folks to sort out their story later.
V2: I have moved the test into schedule_tail where siglock can
be grabbed and recalc_sigpending can be reused directly.
Further as the last action of setting up a new task this
guarantees that TIF_SIGPENDING will be properly set in the
new process.
The helper calculate_sigpending takes the siglock and
uncontitionally sets TIF_SIGPENDING and let's recalc_sigpending
clear TIF_SIGPENDING if it is unnecessary. This allows reusing
the existing code and keeps maintenance of the conditions simple.
Oleg Nesterov <oleg@redhat.com> suggested the movement
and pointed out the need to take siglock if this code
was going to be called while the new task is discoverable.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This patch detaches the preemptirq tracepoints from the tracers and
keeps it separate.
Advantages:
* Lockdep and irqsoff event can now run in parallel since they no longer
have their own calls.
* This unifies the usecase of adding hooks to an irqsoff and irqson
event, and a preemptoff and preempton event.
3 users of the events exist:
- Lockdep
- irqsoff and preemptoff tracers
- irqs and preempt trace events
The unification cleans up several ifdefs and makes the code in preempt
tracer and irqsoff tracers simpler. It gets rid of all the horrific
ifdeferry around PROVE_LOCKING and makes configuration of the different
users of the tracepoints more easy and understandable. It also gets rid
of the time_* function calls from the lockdep hooks used to call into
the preemptirq tracer which is not needed anymore. The negative delta in
lines of code in this patch is quite large too.
In the patch we introduce a new CONFIG option PREEMPTIRQ_TRACEPOINTS
as a single point for registering probes onto the tracepoints. With
this,
the web of config options for preempt/irq toggle tracepoints and its
users becomes:
PREEMPT_TRACER PREEMPTIRQ_EVENTS IRQSOFF_TRACER PROVE_LOCKING
| | \ | |
\ (selects) / \ \ (selects) /
TRACE_PREEMPT_TOGGLE ----> TRACE_IRQFLAGS
\ /
\ (depends on) /
PREEMPTIRQ_TRACEPOINTS
Other than the performance tests mentioned in the previous patch, I also
ran the locking API test suite. I verified that all tests cases are
passing.
I also injected issues by not registering lockdep probes onto the
tracepoints and I see failures to confirm that the probes are indeed
working.
This series + lockdep probes not registered (just to inject errors):
[ 0.000000] hard-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] soft-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] sirq-safe-A => hirqs-on/12:FAILED|FAILED| ok |
[ 0.000000] sirq-safe-A => hirqs-on/21:FAILED|FAILED| ok |
[ 0.000000] hard-safe-A + irqs-on/12:FAILED|FAILED| ok |
[ 0.000000] soft-safe-A + irqs-on/12:FAILED|FAILED| ok |
[ 0.000000] hard-safe-A + irqs-on/21:FAILED|FAILED| ok |
[ 0.000000] soft-safe-A + irqs-on/21:FAILED|FAILED| ok |
[ 0.000000] hard-safe-A + unsafe-B #1/123: ok | ok | ok |
[ 0.000000] soft-safe-A + unsafe-B #1/123: ok | ok | ok |
With this series + lockdep probes registered, all locking tests pass:
[ 0.000000] hard-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] soft-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] sirq-safe-A => hirqs-on/12: ok | ok | ok |
[ 0.000000] sirq-safe-A => hirqs-on/21: ok | ok | ok |
[ 0.000000] hard-safe-A + irqs-on/12: ok | ok | ok |
[ 0.000000] soft-safe-A + irqs-on/12: ok | ok | ok |
[ 0.000000] hard-safe-A + irqs-on/21: ok | ok | ok |
[ 0.000000] soft-safe-A + irqs-on/21: ok | ok | ok |
[ 0.000000] hard-safe-A + unsafe-B #1/123: ok | ok | ok |
[ 0.000000] soft-safe-A + unsafe-B #1/123: ok | ok | ok |
Link: http://lkml.kernel.org/r/20180730222423.196630-4-joel@joelfernandes.org
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
sched_clock_init() used be called early during boot when interrupts were
still disabled. After the recent changes to utilize sched clock early the
sched_clock_init() call happens when interrupts are already enabled, which
triggers the following warning:
WARNING: CPU: 0 PID: 0 at kernel/time/sched_clock.c:180 sched_clock_register+0x44/0x278
[<c001a13c>] (warn_slowpath_null) from [<c052367c>] (sched_clock_register+0x44/0x278)
[<c052367c>] (sched_clock_register) from [<c05238d8>] (generic_sched_clock_init+0x28/0x88)
[<c05238d8>] (generic_sched_clock_init) from [<c0521a00>] (sched_clock_init+0x54/0x74)
[<c0521a00>] (sched_clock_init) from [<c0519c18>] (start_kernel+0x310/0x3e4)
[<c0519c18>] (start_kernel) from [<00000000>] ( (null))
Disable IRQs for the duration of generic_sched_clock_init().
Fixes: 857baa87b6 ("sched/clock: Enable sched clock early")
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: steven.sistare@oracle.com
Cc: daniel.m.jordan@oracle.com
Link: https://lkml.kernel.org/r/20180730135252.24599-1-pasha.tatashin@oracle.com
The metrics for updating scan periods are local or task specific.
Currently this update happens under the numa_group lock, which seems
unnecessary. Hence move this update outside the lock.
Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
16 25355.9 25645.4 1.141
1 72812 72142 -0.92
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1529514181-9842-15-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
task_numa_find_cpu() helps to find the CPU to swap/move the task to.
It's guarded by numa_has_capacity(). However node not having capacity
shouldn't deter a task swapping if it helps NUMA placement.
Further load_too_imbalanced(), which evaluates possibilities of move/swap,
provides similar checks as numa_has_capacity.
Hence remove numa_has_capacity() to enhance possibilities of task
swapping even if load is imbalanced.
Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
16 25657.9 25804.1 0.569
1 74435 73413 -1.37
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1529514181-9842-13-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There are checks in migrate_swap_stop() that check if the task/CPU
combination is as per migrate_swap_arg before migrating.
However atleast one of the two tasks to be swapped by migrate_swap() could
have migrated to a completely different CPU before updating the
migrate_swap_arg. The new CPU where the task is currently running could
be a different node too. If the task has migrated, numa balancer might
end up placing a task in a wrong node. Instead of achieving node
consolidation, it may end up spreading the load across nodes.
To avoid that pass the CPUs as additional parameters.
While here, place migrate_swap under CONFIG_NUMA_BALANCING.
Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
16 25377.3 25226.6 -0.59
1 72287 73326 1.437
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1529514181-9842-10-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The task_capacity field in 'struct numa_stats' is redundant.
Also move nr_running for better packing within the struct.
No functional changes.
Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
16 25308.6 25377.3 0.271
1 72964 72287 -0.92
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1529514181-9842-9-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix the order in which the private and shared numa faults are getting
printed.
No functional changes.
Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
16 25215.7 25375.3 0.63
1 72107 72617 0.70
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1529514181-9842-7-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently preferred node is set to dst_nid which is the last node in the
iteration whose group weight or task weight is greater than the current
node. However it doesn't guarantee that dst_nid has the numa capacity
to move. It also doesn't guarantee that dst_nid has the best_cpu which
is the CPU/node ideal for node migration.
Lets consider faults on a 4 node system with group weight numbers
in different nodes being in 0 < 1 < 2 < 3 proportion. Consider the task
is running on 3 and 0 is its preferred node but its capacity is full.
Consider nodes 1, 2 and 3 have capacity. Then the task should be
migrated to node 1. Currently the task gets moved to node 2. env.dst_nid
points to the last node whose faults were greater than current node.
Modify to set the preferred node based of best_cpu. Earlier setting
preferred node was skipped if nr_active_nodes is 1. This could result in
the task being moved out of the preferred node to a random node during
regular load balancing.
Also while modifying task_numa_migrate(), use sched_setnuma to set
preferred node. This ensures out numa accounting is correct.
Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
16 25122.9 25549.6 1.698
1 73850 73190 -0.89
Running SPECjbb2005 on a 16 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
8 105930 113437 7.08676
1 178624 196130 9.80047
(numbers from v1 based on v4.17-rc5)
Testcase Time: Min Max Avg StdDev
numa01.sh Real: 435.78 653.81 534.58 83.20
numa01.sh Sys: 121.93 187.18 145.90 23.47
numa01.sh User: 37082.81 51402.80 43647.60 5409.75
numa02.sh Real: 60.64 61.63 61.19 0.40
numa02.sh Sys: 14.72 25.68 19.06 4.03
numa02.sh User: 5210.95 5266.69 5233.30 20.82
numa03.sh Real: 746.51 808.24 780.36 23.88
numa03.sh Sys: 97.26 108.48 105.07 4.28
numa03.sh User: 58956.30 61397.05 60162.95 1050.82
numa04.sh Real: 465.97 519.27 484.81 19.62
numa04.sh Sys: 304.43 359.08 334.68 20.64
numa04.sh User: 37544.16 41186.15 39262.44 1314.91
numa05.sh Real: 411.57 457.20 433.29 16.58
numa05.sh Sys: 230.05 435.48 339.95 67.58
numa05.sh User: 33325.54 36896.31 35637.84 1222.64
Testcase Time: Min Max Avg StdDev %Change
numa01.sh Real: 506.35 794.46 599.06 104.26 -10.76%
numa01.sh Sys: 150.37 223.56 195.99 24.94 -25.55%
numa01.sh User: 43450.69 61752.04 49281.50 6635.33 -11.43%
numa02.sh Real: 60.33 62.40 61.31 0.90 -0.195%
numa02.sh Sys: 18.12 31.66 24.28 5.89 -21.49%
numa02.sh User: 5203.91 5325.32 5260.29 49.98 -0.513%
numa03.sh Real: 696.47 853.62 745.80 57.28 4.6339%
numa03.sh Sys: 85.68 123.71 97.89 13.48 7.3347%
numa03.sh User: 55978.45 66418.63 59254.94 3737.97 1.5323%
numa04.sh Real: 444.05 514.83 497.06 26.85 -2.464%
numa04.sh Sys: 230.39 375.79 316.23 48.58 5.8343%
numa04.sh User: 35403.12 41004.10 39720.80 2163.08 -1.153%
numa05.sh Real: 423.09 460.41 439.57 13.92 -1.428%
numa05.sh Sys: 287.38 480.15 369.37 68.52 -7.964%
numa05.sh User: 34732.12 38016.80 36255.85 1070.51 -1.704%
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1529514181-9842-5-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently load_too_imbalance() cares about the slope of imbalance.
It doesn't care of the direction of the imbalance.
However this may not work if nodes that are being compared have
dissimilar capacities. Few nodes might have more cores than other nodes
in the system. Also unlike traditional load balance at a NUMA sched
domain, multiple requests to migrate from the same source node to same
destination node may run in parallel. This can cause huge load
imbalance. This is specially true on a larger machines with either large
cores per node or more number of nodes in the system. Hence allow
move/swap only if the imbalance is going to reduce.
Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
16 25058.2 25122.9 0.25
1 72950 73850 1.23
(numbers from v1 based on v4.17-rc5)
Testcase Time: Min Max Avg StdDev
numa01.sh Real: 516.14 892.41 739.84 151.32
numa01.sh Sys: 153.16 192.99 177.70 14.58
numa01.sh User: 39821.04 69528.92 57193.87 10989.48
numa02.sh Real: 60.91 62.35 61.58 0.63
numa02.sh Sys: 16.47 26.16 21.20 3.85
numa02.sh User: 5227.58 5309.61 5265.17 31.04
numa03.sh Real: 739.07 917.73 795.75 64.45
numa03.sh Sys: 94.46 136.08 109.48 14.58
numa03.sh User: 57478.56 72014.09 61764.48 5343.69
numa04.sh Real: 442.61 715.43 530.31 96.12
numa04.sh Sys: 224.90 348.63 285.61 48.83
numa04.sh User: 35836.84 47522.47 40235.41 3985.26
numa05.sh Real: 386.13 489.17 434.94 43.59
numa05.sh Sys: 144.29 438.56 278.80 105.78
numa05.sh User: 33255.86 36890.82 34879.31 1641.98
Testcase Time: Min Max Avg StdDev %Change
numa01.sh Real: 435.78 653.81 534.58 83.20 38.39%
numa01.sh Sys: 121.93 187.18 145.90 23.47 21.79%
numa01.sh User: 37082.81 51402.80 43647.60 5409.75 31.03%
numa02.sh Real: 60.64 61.63 61.19 0.40 0.637%
numa02.sh Sys: 14.72 25.68 19.06 4.03 11.22%
numa02.sh User: 5210.95 5266.69 5233.30 20.82 0.608%
numa03.sh Real: 746.51 808.24 780.36 23.88 1.972%
numa03.sh Sys: 97.26 108.48 105.07 4.28 4.197%
numa03.sh User: 58956.30 61397.05 60162.95 1050.82 2.661%
numa04.sh Real: 465.97 519.27 484.81 19.62 9.385%
numa04.sh Sys: 304.43 359.08 334.68 20.64 -14.6%
numa04.sh User: 37544.16 41186.15 39262.44 1314.91 2.478%
numa05.sh Real: 411.57 457.20 433.29 16.58 0.380%
numa05.sh Sys: 230.05 435.48 339.95 67.58 -17.9%
numa05.sh User: 33325.54 36896.31 35637.84 1222.64 -2.12%
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1529514181-9842-4-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Although we can rely on cpuacct to present the CPU usage of task
groups, it is hard to tell how intense the competition is between
these groups on CPU resources.
Monitoring the wait time or sched_debug of each process could be
very expensive, and there is no good way to accurately represent the
conflict with these info, we need the wait time on group dimension.
Thus we introduce group's wait_sum to represent the resource conflict
between task groups, which is simply the sum of the wait time of
the group's cfs_rq.
The 'cpu.stat' is modified to show the statistic, like:
nr_periods 0
nr_throttled 0
throttled_time 0
wait_sum 2035098795584
Now we can monitor the changes of wait_sum to tell how much a
a task group is suffering in the fight of CPU resources.
For example:
(wait_sum - last_wait_sum) * 100 / (nr_cpu * period_ns) == X%
means the task group paid X percentage of period on waiting
for the CPU.
Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/ff7dae3b-e5f9-7157-1caa-ff02c6b23dc1@linux.alibaba.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reuse cpu_util_irq() that has been defined for schedutil and set irq util
to 0 when !CONFIG_IRQ_TIME_ACCOUNTING.
But the compiler is not able to optimize the sequence (at least with
aarch64 GCC 7.2.1):
free *= (max - irq);
free /= max;
when irq is fixed to 0
Add a new inline function scale_irq_capacity() that will scale utilization
when irq is accounted. Reuse this funciton in schedutil which applies
similar formula.
Suggested-by: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: rjw@rjwysocki.net
Link: http://lkml.kernel.org/r/1532001606-6689-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
NO_RT_RUNTIME_SHARE feature is used to prevent a CPU borrow enough
runtime with a spin-rt-task.
However, if RT_RUNTIME_SHARE feature is enabled and rt_rq has borrowd
enough rt_runtime at the beginning, rt_runtime can't be restored to
its initial bandwidth rt_runtime after we disable RT_RUNTIME_SHARE.
E.g. on my PC with 4 cores, procedure to reproduce:
1) Make sure RT_RUNTIME_SHARE is enabled
cat /sys/kernel/debug/sched_features
GENTLE_FAIR_SLEEPERS START_DEBIT NO_NEXT_BUDDY LAST_BUDDY
CACHE_HOT_BUDDY WAKEUP_PREEMPTION NO_HRTICK NO_DOUBLE_TICK
LB_BIAS NONTASK_CAPACITY TTWU_QUEUE NO_SIS_AVG_CPU SIS_PROP
NO_WARN_DOUBLE_CLOCK RT_PUSH_IPI RT_RUNTIME_SHARE NO_LB_MIN
ATTACH_AGE_LOAD WA_IDLE WA_WEIGHT WA_BIAS
2) Start a spin-rt-task
./loop_rr &
3) set affinity to the last cpu
taskset -p 8 $pid_of_loop_rr
4) Observe that last cpu have borrowed enough runtime.
cat /proc/sched_debug | grep rt_runtime
.rt_runtime : 950.000000
.rt_runtime : 900.000000
.rt_runtime : 950.000000
.rt_runtime : 1000.000000
5) Disable RT_RUNTIME_SHARE
echo NO_RT_RUNTIME_SHARE > /sys/kernel/debug/sched_features
6) Observe that rt_runtime can not been restored
cat /proc/sched_debug | grep rt_runtime
.rt_runtime : 950.000000
.rt_runtime : 900.000000
.rt_runtime : 950.000000
.rt_runtime : 1000.000000
This patch help to restore rt_runtime after we disable
RT_RUNTIME_SHARE.
Signed-off-by: Hailong Liu <liu.hailong6@zte.com.cn>
Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: zhong.weidong@zte.com.cn
Link: http://lkml.kernel.org/r/1531874815-39357-1-git-send-email-liu.hailong6@zte.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The 'group' variable in sched_domain_debug_one() is not checked
when firstly used in cpumask_test_cpu(cpu, sched_group_span(group)),
but it might be NULL (it is checked later in the following while loop)
and may cause NULL pointer dereference.
We need to check it before using to avoid NULL dereference.
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: zhong.weidong@zte.com.cn
Link: http://lkml.kernel.org/r/1532319547-33335-1-git-send-email-wang.yi59@zte.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Both the implementation and the users' expectation [1] for the various
wakeup primitives have evolved over time, but the documentation has not
kept up with these changes: brings it into 2018.
[1] http://lkml.kernel.org/r/20180424091510.GB4064@hirez.programming.kicks-ass.net
Also applied feedback from Alan Stern.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Akira Yokosawa <akiyks@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Daniel Lustig <dlustig@nvidia.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jade Alglave <j.alglave@ucl.ac.uk>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Maranget <luc.maranget@inria.fr>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: parri.andrea@gmail.com
Link: http://lkml.kernel.org/r/20180716180605.16115-12-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There are 11 interpretations of the requirements described in the header
comment for smp_mb__after_spinlock(): one for each LKMM maintainer, and
one currently encoded in the Cat file. Stick to the latter (until a more
satisfactory solution is available).
This also reworks some snippets related to the barrier to illustrate the
requirements and to link them to the idioms which are relied upon at its
call sites.
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: akiyks@gmail.com
Cc: dhowells@redhat.com
Cc: j.alglave@ucl.ac.uk
Cc: linux-arch@vger.kernel.org
Cc: luc.maranget@inria.fr
Cc: npiggin@gmail.com
Cc: parri.andrea@gmail.com
Cc: stern@rowland.harvard.edu
Link: http://lkml.kernel.org/r/20180716180605.16115-11-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
wake_woken_function() synchronizes with wait_woken() as follows:
[wait_woken] [wake_woken_function]
entry->flags &= ~wq_flag_woken; condition = true;
smp_mb(); smp_wmb();
if (condition) wq_entry->flags |= wq_flag_woken;
break;
This commit replaces the above smp_wmb() with an smp_mb() in order to
guarantee that either wait_woken() sees the wait condition being true
or the store to wq_entry->flags in woken_wake_function() follows the
store in wait_woken() in the coherence order (so that the former can
eventually be observed by wait_woken()).
The commit also fixes a comment associated to set_current_state() in
wait_woken(): the comment pairs the barrier in set_current_state() to
the above smp_wmb(), while the actual pairing involves the barrier in
set_current_state() and the barrier executed by the try_to_wake_up()
in wake_woken_function().
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akiyks@gmail.com
Cc: boqun.feng@gmail.com
Cc: dhowells@redhat.com
Cc: j.alglave@ucl.ac.uk
Cc: linux-arch@vger.kernel.org
Cc: luc.maranget@inria.fr
Cc: npiggin@gmail.com
Cc: parri.andrea@gmail.com
Cc: stern@rowland.harvard.edu
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/20180716180605.16115-10-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
get_cpu() disables preemption for the entire sched_fork() function.
This get_cpu() was introduced in commit:
dd41f596cd ("sched: cfs core code")
... which also invoked sched_balance_self() and this function
required preemption do be off.
Today, sched_balance_self() seems to be moved to ->task_fork callback
which is invoked while the ->pi_lock is held.
set_load_weight() could invoke reweight_task() which then via $callchain
might end up in smp_processor_id() but since `update_load' is false
this won't happen.
I didn't find any this_cpu*() or similar usage during the initialisation
of the task_struct.
The `cpu' value (from get_cpu()) is only used later in __set_task_cpu()
while the ->pi_lock lock is held.
Based on this it is possible to remove get_cpu() and use
smp_processor_id() for the `cpu' variable without breaking anything.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180706130615.g2ex2kmfu5kcvlq6@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The time spent executing IRQ handlers can be significant but it is not reflected
in the utilization of CPU when deciding to choose an OPP. Now that we have
access to this metric, schedutil can take it into account when selecting
the OPP for a CPU.
RQS utilization don't see the time spend under interrupt context and report
their value in the normal context time window. We need to compensate this when
adding interrupt utilization
The CPU utilization is:
IRQ util_avg + (1 - IRQ util_avg / max capacity ) * /Sum rq util_avg
A test with iperf on hikey (octo arm64) gives the following speedup:
iperf -c server_address -r -t 5
w/o patch w/ patch
Tx 276 Mbits/sec 304 Mbits/sec +10%
Rx 299 Mbits/sec 328 Mbits/sec +9%
8 iterations
stdev is lower than 1%
Only WFI idle state is enabled (shallowest idle state).
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: claudio@evidence.eu.com
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: joel@joelfernandes.org
Cc: juri.lelli@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: patrick.bellasi@arm.com
Cc: quentin.perret@arm.com
Cc: rjw@rjwysocki.net
Cc: valentin.schneider@arm.com
Link: http://lkml.kernel.org/r/1530200714-4504-8-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
interrupt and steal time are the only remaining activities tracked by
rt_avg. Like for sched classes, we can use PELT to track their average
utilization of the CPU. But unlike sched class, we don't track when
entering/leaving interrupt; Instead, we take into account the time spent
under interrupt context when we update rqs' clock (rq_clock_task).
This also means that we have to decay the normal context time and account
for interrupt time during the update.
That's also important to note that because:
rq_clock == rq_clock_task + interrupt time
and rq_clock_task is used by a sched class to compute its utilization, the
util_avg of a sched class only reflects the utilization of the time spent
in normal context and not of the whole time of the CPU. The utilization of
interrupt gives an more accurate level of utilization of CPU.
The CPU utilization is:
avg_irq + (1 - avg_irq / max capacity) * /Sum avg_rq
Most of the time, avg_irq is small and neglictible so the use of the
approximation CPU utilization = /Sum avg_rq was enough.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: claudio@evidence.eu.com
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: joel@joelfernandes.org
Cc: juri.lelli@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: patrick.bellasi@arm.com
Cc: quentin.perret@arm.com
Cc: rjw@rjwysocki.net
Cc: valentin.schneider@arm.com
Cc: viresh.kumar@linaro.org
Link: http://lkml.kernel.org/r/1530200714-4504-7-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add both CFS and RT utilization when selecting an OPP for CFS tasks as RT
can preempt and steal CFS's running time.
RT util_avg is used to take into account the utilization of RT tasks
on the CPU when selecting OPP. If a RT task migrate, the RT utilization
will not migrate but will decay over time. On an overloaded CPU, CFS
utilization reflects the remaining utilization avialable on CPU. When RT
task migrates, the CFS utilization will increase when tasks will start to
use the newly available capacity. At the same pace, RT utilization will
decay and both variations will compensate each other to keep unchanged
overall utilization and will prevent any OPP drop.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: claudio@evidence.eu.com
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: joel@joelfernandes.org
Cc: juri.lelli@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: patrick.bellasi@arm.com
Cc: quentin.perret@arm.com
Cc: rjw@rjwysocki.net
Cc: valentin.schneider@arm.com
Link: http://lkml.kernel.org/r/1530200714-4504-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a new task wakes-up for the first time, its initial utilization
is set to half of the spare capacity of its CPU. The current
implementation of post_init_entity_util_avg() uses SCHED_CAPACITY_SCALE
directly as a capacity reference. As a result, on a big.LITTLE system, a
new task waking up on an idle little CPU will be given ~512 of util_avg,
even if the CPU's capacity is significantly less than that.
Fix this by computing the spare capacity with arch_scale_cpu_capacity().
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: morten.rasmussen@arm.com
Cc: patrick.bellasi@arm.com
Link: http://lkml.kernel.org/r/20180612112215.25448-1-quentin.perret@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Mark noticed that syzkaller is able to reliably trigger the following warning:
dl_rq->running_bw > dl_rq->this_bw
WARNING: CPU: 1 PID: 153 at kernel/sched/deadline.c:124 switched_from_dl+0x454/0x608
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 153 Comm: syz-executor253 Not tainted 4.18.0-rc3+ #29
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace+0x0/0x458
show_stack+0x20/0x30
dump_stack+0x180/0x250
panic+0x2dc/0x4ec
__warn_printk+0x0/0x150
report_bug+0x228/0x2d8
bug_handler+0xa0/0x1a0
brk_handler+0x2f0/0x568
do_debug_exception+0x1bc/0x5d0
el1_dbg+0x18/0x78
switched_from_dl+0x454/0x608
__sched_setscheduler+0x8cc/0x2018
sys_sched_setattr+0x340/0x758
el0_svc_naked+0x30/0x34
syzkaller reproducer runs a bunch of threads that constantly switch
between DEADLINE and NORMAL classes while interacting through futexes.
The splat above is caused by the fact that if a DEADLINE task is setattr
back to NORMAL while in non_contending state (blocked on a futex -
inactive timer armed), its contribution to running_bw is not removed
before sub_rq_bw() gets called (!task_on_rq_queued() branch) and the
latter sees running_bw > this_bw.
Fix it by removing a task contribution from running_bw if the task is
not queued and in non_contending state while switched to a different
class.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Reviewed-by: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: claudio@evidence.eu.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20180711072948.27061-1-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Gaurav reports that commit:
85f1abe001 ("kthread, sched/wait: Fix kthread_parkme() completion issue")
isn't working for him. Because of the following race:
> controller Thread CPUHP Thread
> takedown_cpu
> kthread_park
> kthread_parkme
> Set KTHREAD_SHOULD_PARK
> smpboot_thread_fn
> set Task interruptible
>
>
> wake_up_process
> if (!(p->state & state))
> goto out;
>
> Kthread_parkme
> SET TASK_PARKED
> schedule
> raw_spin_lock(&rq->lock)
> ttwu_remote
> waiting for __task_rq_lock
> context_switch
>
> finish_lock_switch
>
>
>
> Case TASK_PARKED
> kthread_park_complete
>
>
> SET Running
Furthermore, Oleg noticed that the whole scheduler TASK_PARKED
handling is buggered because the TASK_DEAD thing is done with
preemption disabled, the current code can still complete early on
preemption :/
So basically revert that earlier fix and go with a variant of the
alternative mentioned in the commit. Promote TASK_PARKED to special
state to avoid the store-store issue on task->state leading to the
WARN in kthread_unpark() -> __kthread_bind().
But in addition, add wait_task_inactive() to kthread_park() to ensure
the task really is PARKED when we return from kthread_park(). This
avoids the whole kthread still gets migrated nonsense -- although it
would be really good to get this done differently.
Reported-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 85f1abe001 ("kthread, sched/wait: Fix kthread_parkme() completion issue")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a cfs_rq is throttled, parent cfs_rq->nr_running is decreased and
everything happens at cfs_rq level. Currently util_est stays unchanged
in such case and it keeps accounting the utilization of throttled tasks.
This can somewhat make sense as we don't dequeue tasks but only throttled
cfs_rq.
If a task of another group is enqueued/dequeued and root cfs_rq becomes
idle during the dequeue, util_est will be cleared whereas it was
accounting util_est of throttled tasks before. So the behavior of util_est
is not always the same regarding throttled tasks and depends of side
activity. Furthermore, util_est will not be updated when the cfs_rq is
unthrottled as everything happens at cfs_rq level. Main results is that
util_est will stay null whereas we now have running tasks. We have to wait
for the next dequeue/enqueue of the previously throttled tasks to get an
up to date util_est.
Remove the assumption that cfs_rq's estimated utilization of a CPU is 0
if there is no running task so the util_est of a task remains until the
latter is dequeued even if its cfs_rq has been throttled.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 7f65ea42eb ("sched/fair: Add util_est on top of PELT")
Link: http://lkml.kernel.org/r/1528972380-16268-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When period gets restarted after some idle time, start_cfs_bandwidth()
doesn't update the expiration information, expire_cfs_rq_runtime() will
see cfs_rq->runtime_expires smaller than rq clock and go to the clock
drift logic, wasting needless CPU cycles on the scheduler hot path.
Update the global expiration in start_cfs_bandwidth() to avoid frequent
expire_cfs_rq_runtime() calls once a new period begins.
Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180620101834.24455-2-xlpang@linux.alibaba.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
I noticed that cgroup task groups constantly get throttled even
if they have low CPU usage, this causes some jitters on the response
time to some of our business containers when enabling CPU quotas.
It's very simple to reproduce:
mkdir /sys/fs/cgroup/cpu/test
cd /sys/fs/cgroup/cpu/test
echo 100000 > cpu.cfs_quota_us
echo $$ > tasks
then repeat:
cat cpu.stat | grep nr_throttled # nr_throttled will increase steadily
After some analysis, we found that cfs_rq::runtime_remaining will
be cleared by expire_cfs_rq_runtime() due to two equal but stale
"cfs_{b|q}->runtime_expires" after period timer is re-armed.
The current condition to judge clock drift in expire_cfs_rq_runtime()
is wrong, the two runtime_expires are actually the same when clock
drift happens, so this condtion can never hit. The orginal design was
correctly done by this commit:
a9cf55b286 ("sched: Expire invalid runtime")
... but was changed to be the current implementation due to its locking bug.
This patch introduces another way, it adds a new field in both structures
cfs_rq and cfs_bandwidth to record the expiration update sequence, and
uses them to figure out if clock drift happens (true if they are equal).
Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 51f2176d74 ("sched/fair: Fix unlocked reads of some cfs_b->quota/period")
Link: http://lkml.kernel.org/r/20180620101834.24455-1-xlpang@linux.alibaba.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With commit:
8f111bc357 ("cpufreq/schedutil: Rewrite CPUFREQ_RT support")
the schedutil governor uses rq->rt.rt_nr_running to detect whether an
RT task is currently running on the CPU and to set frequency to max
if necessary.
cpufreq_update_util() is called in enqueue/dequeue_top_rt_rq() but
rq->rt.rt_nr_running has not been updated yet when dequeue_top_rt_rq() is
called so schedutil still considers that an RT task is running when the
last task is dequeued. The update of rq->rt.rt_nr_running happens later
in dequeue_rt_stack().
In fact, we can take advantage of the sequence that the dequeue then
re-enqueue rt entities when a rt task is enqueued or dequeued;
As a result enqueue_top_rt_rq() is always called when a task is
enqueued or dequeued and also when groups are throttled or unthrottled.
The only place that not use enqueue_top_rt_rq() is when root rt_rq is
throttled.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: efault@gmx.de
Cc: juri.lelli@redhat.com
Cc: patrick.bellasi@arm.com
Cc: viresh.kumar@linaro.org
Fixes: 8f111bc357 ('cpufreq/schedutil: Rewrite CPUFREQ_RT support')
Link: http://lkml.kernel.org/r/1530021202-21695-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Some people have reported that the warning in sched_tick_remote()
occasionally triggers, especially in favour of some RCU-Torture
pressure:
WARNING: CPU: 11 PID: 906 at kernel/sched/core.c:3138 sched_tick_remote+0xb6/0xc0
Modules linked in:
CPU: 11 PID: 906 Comm: kworker/u32:3 Not tainted 4.18.0-rc2+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
Workqueue: events_unbound sched_tick_remote
RIP: 0010:sched_tick_remote+0xb6/0xc0
Code: e8 0f 06 b8 00 c6 03 00 fb eb 9d 8b 43 04 85 c0 75 8d 48 8b 83 e0 0a 00 00 48 85 c0 75 81 eb 88 48 89 df e8 bc fe ff ff eb aa <0f> 0b eb
+c5 66 0f 1f 44 00 00 bf 17 00 00 00 e8 b6 2e fe ff 0f b6
Call Trace:
process_one_work+0x1df/0x3b0
worker_thread+0x44/0x3d0
kthread+0xf3/0x130
? set_worker_desc+0xb0/0xb0
? kthread_create_worker_on_cpu+0x70/0x70
ret_from_fork+0x35/0x40
This happens when the remote tick applies on an idle task. Usually the
idle_cpu() check avoids that, but it is performed before we lock the
runqueue and it is therefore racy. It was intended to be that way in
order to prevent from useless runqueue locks since idle task tick
callback is a no-op.
Now if the racy check slips out of our hands and we end up remotely
ticking an idle task, the empty task_tick_idle() is harmless. Still
it won't pass the WARN_ON_ONCE() test that ensures rq_clock_task() is
not too far from curr->se.exec_start because update_curr_idle() doesn't
update the exec_start value like other scheduler policies. Hence the
reported false positive.
So let's have another check, while the rq is locked, to make sure we
don't remote tick on an idle task. The lockless idle_cpu() still applies
to avoid unecessary rq lock contention.
Reported-by: Jacek Tomaka <jacekt@dug.com>
Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reported-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1530203381-31234-1-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After commit:
82958366cf ("sched: Replace update_shares weight distribution with per-entity computation")
tg_unthrottle_up() did not update the weight.
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/lkml/1523423816-18322-1-git-send-email-lirongqing@baidu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
match_string() returns the index of an array for a matching string,
which can be used instead of the open coded variant.
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/1527765086-19873-15-git-send-email-xieyisheng1@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The static key sched_smt_present is only updated at boot time when SMT
siblings have been detected. Booting with maxcpus=1 and bringing the
siblings online after boot rebuilds the scheduling domains correctly but
does not update the static key, so the SMT code is not enabled.
Let the key be updated in the scheduler CPU hotplug code to fix this.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Linus noted that swait basically implements exclusive mode -- because
swake_up() only wakes a single waiter. And because of that it should
take care to properly deal with the interruptible case.
In short, the problem is that swake_up() can race with a signal. In
this this case it is possible the swake_up() 'wakes' the waiter that
is already on the way out because it just got a signal and the wakeup
gets lost.
The normal wait code is very careful and avoids this situation, make
sure we do too.
Copy the exact exclusive semantics from wait.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: bigeasy@linutronix.de
Cc: oleg@redhat.com
Cc: paulmck@linux.vnet.ibm.com
Cc: pbonzini@redhat.com
Link: https://lkml.kernel.org/r/20180612083909.209762413@infradead.org
During a context switch, we first switch_mm() to the next task's mm,
then switch_to() that new task. This means that vmalloc'd regions which
had previously been faulted in can transiently disappear in the context
of the prev task.
Functions instrumented by KCOV may try to access a vmalloc'd kcov_area
during this window, and as the fault handling code is instrumented, this
results in a recursive fault.
We must avoid accessing any kcov_area during this window. We can do so
with a new flag in kcov_mode, set prior to switching the mm, and cleared
once the new task is live. Since task_struct::kcov_mode isn't always a
specific enum kcov_mode value, this is made an unsigned int.
The manipulation is hidden behind kcov_{prepare,finish}_switch() helpers,
which are empty for !CONFIG_KCOV kernels.
The code uses macros because I can't use static inline functions without a
circular include dependency between <linux/sched.h> and <linux/kcov.h>,
since the definition of task_struct uses things defined in <linux/kcov.h>
Link: http://lkml.kernel.org/r/20180504135535.53744-4-mark.rutland@arm.com
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull restartable sequence support from Thomas Gleixner:
"The restartable sequences syscall (finally):
After a lot of back and forth discussion and massive delays caused by
the speculative distraction of maintainers, the core set of
restartable sequences has finally reached a consensus.
It comes with the basic non disputed core implementation along with
support for arm, powerpc and x86 and a full set of selftests
It was exposed to linux-next earlier this week, so it does not fully
comply with the merge window requirements, but there is really no
point to drag it out for yet another cycle"
* 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rseq/selftests: Provide Makefile, scripts, gitignore
rseq/selftests: Provide parametrized tests
rseq/selftests: Provide basic percpu ops test
rseq/selftests: Provide basic test
rseq/selftests: Provide rseq library
selftests/lib.mk: Introduce OVERRIDE_TARGETS
powerpc: Wire up restartable sequences system call
powerpc: Add syscall detection for restartable sequences
powerpc: Add support for restartable sequences
x86: Wire up restartable sequence system call
x86: Add support for restartable sequences
arm: Wire up restartable sequences system call
arm: Add syscall detection for restartable sequences
arm: Add restartable sequences support
rseq: Introduce restartable sequences system call
uapi/headers: Provide types_32_64.h
Expose a new system call allowing each thread to register one userspace
memory area to be used as an ABI between kernel and user-space for two
purposes: user-space restartable sequences and quick access to read the
current CPU number value from user-space.
* Restartable sequences (per-cpu atomics)
Restartables sequences allow user-space to perform update operations on
per-cpu data without requiring heavy-weight atomic operations.
The restartable critical sections (percpu atomics) work has been started
by Paul Turner and Andrew Hunter. It lets the kernel handle restart of
critical sections. [1] [2] The re-implementation proposed here brings a
few simplifications to the ABI which facilitates porting to other
architectures and speeds up the user-space fast path.
Here are benchmarks of various rseq use-cases.
Test hardware:
arm32: ARMv7 Processor rev 4 (v7l) "Cubietruck", 2-core
x86-64: Intel E5-2630 v3@2.40GHz, 16-core, hyperthreading
The following benchmarks were all performed on a single thread.
* Per-CPU statistic counter increment
getcpu+atomic (ns/op) rseq (ns/op) speedup
arm32: 344.0 31.4 11.0
x86-64: 15.3 2.0 7.7
* LTTng-UST: write event 32-bit header, 32-bit payload into tracer
per-cpu buffer
getcpu+atomic (ns/op) rseq (ns/op) speedup
arm32: 2502.0 2250.0 1.1
x86-64: 117.4 98.0 1.2
* liburcu percpu: lock-unlock pair, dereference, read/compare word
getcpu+atomic (ns/op) rseq (ns/op) speedup
arm32: 751.0 128.5 5.8
x86-64: 53.4 28.6 1.9
* jemalloc memory allocator adapted to use rseq
Using rseq with per-cpu memory pools in jemalloc at Facebook (based on
rseq 2016 implementation):
The production workload response-time has 1-2% gain avg. latency, and
the P99 overall latency drops by 2-3%.
* Reading the current CPU number
Speeding up reading the current CPU number on which the caller thread is
running is done by keeping the current CPU number up do date within the
cpu_id field of the memory area registered by the thread. This is done
by making scheduler preemption set the TIF_NOTIFY_RESUME flag on the
current thread. Upon return to user-space, a notify-resume handler
updates the current CPU value within the registered user-space memory
area. User-space can then read the current CPU number directly from
memory.
Keeping the current cpu id in a memory area shared between kernel and
user-space is an improvement over current mechanisms available to read
the current CPU number, which has the following benefits over
alternative approaches:
- 35x speedup on ARM vs system call through glibc
- 20x speedup on x86 compared to calling glibc, which calls vdso
executing a "lsl" instruction,
- 14x speedup on x86 compared to inlined "lsl" instruction,
- Unlike vdso approaches, this cpu_id value can be read from an inline
assembly, which makes it a useful building block for restartable
sequences.
- The approach of reading the cpu id through memory mapping shared
between kernel and user-space is portable (e.g. ARM), which is not the
case for the lsl-based x86 vdso.
On x86, yet another possible approach would be to use the gs segment
selector to point to user-space per-cpu data. This approach performs
similarly to the cpu id cache, but it has two disadvantages: it is
not portable, and it is incompatible with existing applications already
using the gs segment selector for other purposes.
Benchmarking various approaches for reading the current CPU number:
ARMv7 Processor rev 4 (v7l)
Machine model: Cubietruck
- Baseline (empty loop): 8.4 ns
- Read CPU from rseq cpu_id: 16.7 ns
- Read CPU from rseq cpu_id (lazy register): 19.8 ns
- glibc 2.19-0ubuntu6.6 getcpu: 301.8 ns
- getcpu system call: 234.9 ns
x86-64 Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz:
- Baseline (empty loop): 0.8 ns
- Read CPU from rseq cpu_id: 0.8 ns
- Read CPU from rseq cpu_id (lazy register): 0.8 ns
- Read using gs segment selector: 0.8 ns
- "lsl" inline assembly: 13.0 ns
- glibc 2.19-0ubuntu6 getcpu: 16.6 ns
- getcpu system call: 53.9 ns
- Speed (benchmark taken on v8 of patchset)
Running 10 runs of hackbench -l 100000 seems to indicate, contrary to
expectations, that enabling CONFIG_RSEQ slightly accelerates the
scheduler:
Configuration: 2 sockets * 8-core Intel(R) Xeon(R) CPU E5-2630 v3 @
2.40GHz (directly on hardware, hyperthreading disabled in BIOS, energy
saving disabled in BIOS, turboboost disabled in BIOS, cpuidle.off=1
kernel parameter), with a Linux v4.6 defconfig+localyesconfig,
restartable sequences series applied.
* CONFIG_RSEQ=n
avg.: 41.37 s
std.dev.: 0.36 s
* CONFIG_RSEQ=y
avg.: 40.46 s
std.dev.: 0.33 s
- Size
On x86-64, between CONFIG_RSEQ=n/y, the text size increase of vmlinux is
567 bytes, and the data size increase of vmlinux is 5696 bytes.
[1] https://lwn.net/Articles/650333/
[2] http://www.linuxplumbersconf.org/2013/ocw/system/presentations/1695/original/LPC%20-%20PerCpu%20Atomics.pdf
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Chris Lameter <cl@linux.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Andrew Hunter <ahh@google.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Maurer <bmaurer@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-api@vger.kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20151027235635.16059.11630.stgit@pjt-glaptop.roam.corp.google.com
Link: http://lkml.kernel.org/r/20150624222609.6116.86035.stgit@kitami.mtv.corp.google.com
Link: https://lkml.kernel.org/r/20180602124408.8430-3-mathieu.desnoyers@efficios.com
These include a significant update of the generic power domains (genpd)
and Operating Performance Points (OPP) frameworks, mostly related to
the introduction of power domain performance levels, cpufreq updates
(new driver for Qualcomm Kryo processors, updates of the existing
drivers, some core fixes, schedutil governor improvements), PCI power
management fixes, ACPI workaround for EC-based wakeup events handling
on resume from suspend-to-idle, and major updates of the turbostat
and pm-graph utilities.
Specifics:
- Introduce power domain performance levels into the the generic
power domains (genpd) and Operating Performance Points (OPP)
frameworks (Viresh Kumar, Rajendra Nayak, Dan Carpenter).
- Fix two issues in the runtime PM framework related to the
initialization and removal of devices using device links (Ulf
Hansson).
- Clean up the initialization of drivers for devices in PM domains
(Ulf Hansson, Geert Uytterhoeven).
- Fix a cpufreq core issue related to the policy sysfs interface
causing CPU online to fail for CPUs sharing one cpufreq policy in
some situations (Tao Wang).
- Make it possible to use platform-specific suspend/resume hooks
in the cpufreq-dt driver and make the Armada 37xx DVFS use that
feature (Viresh Kumar, Miquel Raynal).
- Optimize policy transition notifications in cpufreq (Viresh Kumar).
- Improve the iowait boost mechanism in the schedutil cpufreq
governor (Patrick Bellasi).
- Improve the handling of deferred frequency updates in the
schedutil cpufreq governor (Joel Fernandes, Dietmar Eggemann,
Rafael Wysocki, Viresh Kumar).
- Add a new cpufreq driver for Qualcomm Kryo (Ilia Lin).
- Fix and clean up some cpufreq drivers (Colin Ian King, Dmitry
Osipenko, Doug Smythies, Luc Van Oostenryck, Simon Horman,
Viresh Kumar).
- Fix the handling of PCI devices with the DPM_SMART_SUSPEND flag
set and update stale comments in the PCI core PM code (Rafael
Wysocki).
- Work around an issue related to the handling of EC-based wakeup
events in the ACPI PM core during resume from suspend-to-idle if
the EC has been put into the low-power mode (Rafael Wysocki).
- Improve the handling of wakeup source objects in the PM core (Doug
Berger, Mahendran Ganesh, Rafael Wysocki).
- Update the driver core to prevent deferred probe from breaking
suspend/resume ordering (Feng Kan).
- Clean up the PM core somewhat (Bjorn Helgaas, Ulf Hansson, Rafael
Wysocki).
- Make the core suspend/resume code and cpufreq support the RT patch
(Sebastian Andrzej Siewior, Thomas Gleixner).
- Consolidate the PM QoS handling in cpuidle governors (Rafael
Wysocki).
- Fix a possible crash in the hibernation core (Tetsuo Handa).
- Update the rockchip-io Adaptive Voltage Scaling (AVS) driver
(David Wu).
- Update the turbostat utility (fixes, cleanups, new CPU IDs, new
command line options, built-in "Low Power Idle" counters support,
new POLL and POLL% columns) and add an entry for it to MAINTAINERS
(Len Brown, Artem Bityutskiy, Chen Yu, Laura Abbott, Matt Turner,
Prarit Bhargava, Srinivas Pandruvada).
- Update the pm-graph to version 5.1 (Todd Brandt).
- Update the intel_pstate_tracer utility (Doug Smythies).
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2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=wqBV
-----END PGP SIGNATURE-----
Merge tag 'pm-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"These include a significant update of the generic power domains
(genpd) and Operating Performance Points (OPP) frameworks, mostly
related to the introduction of power domain performance levels,
cpufreq updates (new driver for Qualcomm Kryo processors, updates of
the existing drivers, some core fixes, schedutil governor
improvements), PCI power management fixes, ACPI workaround for
EC-based wakeup events handling on resume from suspend-to-idle, and
major updates of the turbostat and pm-graph utilities.
Specifics:
- Introduce power domain performance levels into the the generic
power domains (genpd) and Operating Performance Points (OPP)
frameworks (Viresh Kumar, Rajendra Nayak, Dan Carpenter).
- Fix two issues in the runtime PM framework related to the
initialization and removal of devices using device links (Ulf
Hansson).
- Clean up the initialization of drivers for devices in PM domains
(Ulf Hansson, Geert Uytterhoeven).
- Fix a cpufreq core issue related to the policy sysfs interface
causing CPU online to fail for CPUs sharing one cpufreq policy in
some situations (Tao Wang).
- Make it possible to use platform-specific suspend/resume hooks in
the cpufreq-dt driver and make the Armada 37xx DVFS use that
feature (Viresh Kumar, Miquel Raynal).
- Optimize policy transition notifications in cpufreq (Viresh Kumar).
- Improve the iowait boost mechanism in the schedutil cpufreq
governor (Patrick Bellasi).
- Improve the handling of deferred frequency updates in the schedutil
cpufreq governor (Joel Fernandes, Dietmar Eggemann, Rafael Wysocki,
Viresh Kumar).
- Add a new cpufreq driver for Qualcomm Kryo (Ilia Lin).
- Fix and clean up some cpufreq drivers (Colin Ian King, Dmitry
Osipenko, Doug Smythies, Luc Van Oostenryck, Simon Horman, Viresh
Kumar).
- Fix the handling of PCI devices with the DPM_SMART_SUSPEND flag set
and update stale comments in the PCI core PM code (Rafael Wysocki).
- Work around an issue related to the handling of EC-based wakeup
events in the ACPI PM core during resume from suspend-to-idle if
the EC has been put into the low-power mode (Rafael Wysocki).
- Improve the handling of wakeup source objects in the PM core (Doug
Berger, Mahendran Ganesh, Rafael Wysocki).
- Update the driver core to prevent deferred probe from breaking
suspend/resume ordering (Feng Kan).
- Clean up the PM core somewhat (Bjorn Helgaas, Ulf Hansson, Rafael
Wysocki).
- Make the core suspend/resume code and cpufreq support the RT patch
(Sebastian Andrzej Siewior, Thomas Gleixner).
- Consolidate the PM QoS handling in cpuidle governors (Rafael
Wysocki).
- Fix a possible crash in the hibernation core (Tetsuo Handa).
- Update the rockchip-io Adaptive Voltage Scaling (AVS) driver (David
Wu).
- Update the turbostat utility (fixes, cleanups, new CPU IDs, new
command line options, built-in "Low Power Idle" counters support,
new POLL and POLL% columns) and add an entry for it to MAINTAINERS
(Len Brown, Artem Bityutskiy, Chen Yu, Laura Abbott, Matt Turner,
Prarit Bhargava, Srinivas Pandruvada).
- Update the pm-graph to version 5.1 (Todd Brandt).
- Update the intel_pstate_tracer utility (Doug Smythies)"
* tag 'pm-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (128 commits)
tools/power turbostat: update version number
tools/power turbostat: Add Node in output
tools/power turbostat: add node information into turbostat calculations
tools/power turbostat: remove num_ from cpu_topology struct
tools/power turbostat: rename num_cores_per_pkg to num_cores_per_node
tools/power turbostat: track thread ID in cpu_topology
tools/power turbostat: Calculate additional node information for a package
tools/power turbostat: Fix node and siblings lookup data
tools/power turbostat: set max_num_cpus equal to the cpumask length
tools/power turbostat: if --num_iterations, print for specific number of iterations
tools/power turbostat: Add Cannon Lake support
tools/power turbostat: delete duplicate #defines
x86: msr-index.h: Correct SNB_C1/C3_AUTO_UNDEMOTE defines
tools/power turbostat: Correct SNB_C1/C3_AUTO_UNDEMOTE defines
tools/power turbostat: add POLL and POLL% column
tools/power turbostat: Fix --hide Pk%pc10
tools/power turbostat: Build-in "Low Power Idle" counters support
tools/power turbostat: Don't make man pages executable
tools/power turbostat: remove blank lines
tools/power turbostat: a small C-states dump readability immprovement
...
Pull scheduler updates from Ingo Molnar:
- power-aware scheduling improvements (Patrick Bellasi)
- NUMA balancing improvements (Mel Gorman)
- vCPU scheduling fixes (Rohit Jain)
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Update util_est before updating schedutil
sched/cpufreq: Modify aggregate utilization to always include blocked FAIR utilization
sched/deadline/Documentation: Add overrun signal and GRUB-PA documentation
sched/core: Distinguish between idle_cpu() calls based on desired effect, introduce available_idle_cpu()
sched/wait: Include <linux/wait.h> in <linux/swait.h>
sched/numa: Stagger NUMA balancing scan periods for new threads
sched/core: Don't schedule threads on pre-empted vCPUs
sched/fair: Avoid calling sync_entity_load_avg() unnecessarily
sched/fair: Rearrange select_task_rq_fair() to optimize it
Pull RCU updates from Ingo Molnar:
- updates to the handling of expedited grace periods
- updates to reduce lock contention in the rcu_node combining tree
[ These are in preparation for the consolidation of RCU-bh,
RCU-preempt, and RCU-sched into a single flavor, which was
requested by Linus in response to a security flaw whose root cause
included confusion between the multiple flavors of RCU ]
- torture-test updates that save their users some time and effort
- miscellaneous fixes
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
rcu/x86: Provide early rcu_cpu_starting() callback
torture: Make kvm-find-errors.sh find build warnings
rcutorture: Abbreviate kvm.sh summary lines
rcutorture: Print end-of-test state in kvm.sh summary
rcutorture: Print end-of-test state
torture: Fold parse-torture.sh into parse-console.sh
torture: Add a script to edit output from failed runs
rcu: Update list of rcu_future_grace_period() trace events
rcu: Drop early GP request check from rcu_gp_kthread()
rcu: Simplify and inline cpu_needs_another_gp()
rcu: The rcu_gp_cleanup() function does not need cpu_needs_another_gp()
rcu: Make rcu_start_this_gp() check for out-of-range requests
rcu: Add funnel locking to rcu_start_this_gp()
rcu: Make rcu_start_future_gp() caller select grace period
rcu: Inline rcu_start_gp_advanced() into rcu_start_future_gp()
rcu: Clear request other than RCU_GP_FLAG_INIT at GP end
rcu: Cleanup, don't put ->completed into an int
rcu: Switch __rcu_process_callbacks() to rcu_accelerate_cbs()
rcu: Avoid __call_rcu_core() root rcu_node ->lock acquisition
rcu: Make rcu_migrate_callbacks wake GP kthread when needed
...
A missing clock update is causing the following warning:
rq->clock_update_flags < RQCF_ACT_SKIP
WARNING: CPU: 10 PID: 0 at kernel/sched/sched.h:963 inactive_task_timer+0x5d6/0x720
Call Trace:
<IRQ>
__hrtimer_run_queues+0x10f/0x530
hrtimer_interrupt+0xe5/0x240
smp_apic_timer_interrupt+0x79/0x2b0
apic_timer_interrupt+0xf/0x20
</IRQ>
do_idle+0x203/0x280
cpu_startup_entry+0x6f/0x80
start_secondary+0x1b0/0x200
secondary_startup_64+0xa5/0xb0
hardirqs last enabled at (793919): [<ffffffffa27c5f6e>] cpuidle_enter_state+0x9e/0x360
hardirqs last disabled at (793920): [<ffffffffa2a0096e>] interrupt_entry+0xce/0xe0
softirqs last enabled at (793922): [<ffffffffa20bef78>] irq_enter+0x68/0x70
softirqs last disabled at (793921): [<ffffffffa20bef5d>] irq_enter+0x4d/0x70
This happens because inactive_task_timer() calls sub_running_bw() (if
TASK_DEAD and non_contending) that might trigger a schedutil update,
which might access the clock. Clock is however currently updated only
later in inactive_task_timer() function.
Fix the problem by updating the clock right after task_rq_lock().
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180530160809.9074-1-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
select_task_rq() is used in a few paths to select the CPU upon which a
thread should be run - for example it is used by try_to_wake_up() & by
fork or exec balancing. As-is it allows use of any online CPU that is
present in the task's cpus_allowed mask.
This presents a problem because there is a period whilst CPUs are
brought online where a CPU is marked online, but is not yet fully
initialized - ie. the period where CPUHP_AP_ONLINE_IDLE <= state <
CPUHP_ONLINE. Usually we don't run any user tasks during this window,
but there are corner cases where this can happen. An example observed
is:
- Some user task A, running on CPU X, forks to create task B.
- sched_fork() calls __set_task_cpu() with cpu=X, setting task B's
task_struct::cpu field to X.
- CPU X is offlined.
- Task A, currently somewhere between the __set_task_cpu() in
copy_process() and the call to wake_up_new_task(), is migrated to
CPU Y by migrate_tasks() when CPU X is offlined.
- CPU X is onlined, but still in the CPUHP_AP_ONLINE_IDLE state. The
scheduler is now active on CPU X, but there are no user tasks on
the runqueue.
- Task A runs on CPU Y & reaches wake_up_new_task(). This calls
select_task_rq() with cpu=X, taken from task B's task_struct,
and select_task_rq() allows CPU X to be returned.
- Task A enqueues task B on CPU X's runqueue, via activate_task() &
enqueue_task().
- CPU X now has a user task on its runqueue before it has reached the
CPUHP_ONLINE state.
In most cases, the user tasks that schedule on the newly onlined CPU
have no idea that anything went wrong, but one case observed to be
problematic is if the task goes on to invoke the sched_setaffinity
syscall. The newly onlined CPU reaches the CPUHP_AP_ONLINE_IDLE state
before the CPU that brought it online calls stop_machine_unpark(). This
means that for a portion of the window of time between
CPUHP_AP_ONLINE_IDLE & CPUHP_ONLINE the newly onlined CPU's struct
cpu_stopper has its enabled field set to false. If a user thread is
executed on the CPU during this window and it invokes sched_setaffinity
with a CPU mask that does not include the CPU it's running on, then when
__set_cpus_allowed_ptr() calls stop_one_cpu() intending to invoke
migration_cpu_stop() and perform the actual migration away from the CPU
it will simply return -ENOENT rather than calling migration_cpu_stop().
We then return from the sched_setaffinity syscall back to the user task
that is now running on a CPU which it just asked not to run on, and
which is not present in its cpus_allowed mask.
This patch resolves the problem by having select_task_rq() enforce that
user tasks run on CPUs that are active - the same requirement that
select_fallback_rq() already enforces. This should ensure that newly
onlined CPUs reach the CPUHP_AP_ACTIVE state before being able to
schedule user tasks, and also implies that bringup_wait_for_ap() will
have called stop_machine_unpark() which resolves the sched_setaffinity
issue above.
I haven't yet investigated them, but it may be of interest to review
whether any of the actions performed by hotplug states between
CPUHP_AP_ONLINE_IDLE & CPUHP_AP_ACTIVE could have similar unintended
effects on user tasks that might schedule before they are reached, which
might widen the scope of the problem from just affecting the behaviour
of sched_setaffinity.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180526154648.11635-2-paul.burton@mips.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As already enforced by the WARN() in __set_cpus_allowed_ptr(), the rules
for running on an online && !active CPU are stricter than just being a
kthread, you need to be a per-cpu kthread.
If you're not strictly per-CPU, you have better CPUs to run on and
don't need the partially booted one to get your work done.
The exception is to allow smpboot threads to bootstrap the CPU itself
and get kernel 'services' initialized before we allow userspace on it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 955dbdf4ce ("sched: Allow migrating kthreads into online but inactive CPUs")
Link: http://lkml.kernel.org/r/20170725165821.cejhb7v2s3kecems@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a task is enqueued the estimated utilization of a CPU is updated
to better support the selection of the required frequency.
However, schedutil is (implicitly) updated by update_load_avg() which
always happens before util_est_{en,de}queue(), thus potentially
introducing a latency between estimated utilization updates and
frequency selections.
Let's update util_est at the beginning of enqueue_task_fair(),
which will ensure that all schedutil updates will see the most
updated estimated utilization value for a CPU.
Reported-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Fixes: 7f65ea42eb ("sched/fair: Add util_est on top of PELT")
Link: http://lkml.kernel.org/r/20180524141023.13765-3-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since the refactoring introduced by:
commit 8f111bc357 ("cpufreq/schedutil: Rewrite CPUFREQ_RT support")
we aggregate FAIR utilization only if this class has runnable tasks.
This was mainly due to avoid the risk to stay on an high frequency just
because of the blocked utilization of a CPU not being properly decayed
while the CPU was idle.
However, since:
commit 31e77c93e4 ("sched/fair: Update blocked load when newly idle")
the FAIR blocked utilization is properly decayed also for IDLE CPUs.
This allows us to use the FAIR blocked utilization as a safe mechanism
to gracefully reduce the frequency only if no FAIR tasks show up on a
CPU for a reasonable period of time.
Moreover, we also reduce the frequency drops of CPUs running periodic
tasks which, depending on the task periodicity and the time required
for a frequency switch, was increasing the chances to introduce some
undesirable performance variations.
Reported-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Link: http://lkml.kernel.org/r/20180524141023.13765-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 152db033d7 (schedutil: Allow cpufreq requests to be made
even when kthread kicked) made changes to prevent utilization updates
from being discarded during processing a previous request, but it
left a small window in which that still can happen in the one-CPU
policy case. Namely, updates coming in after setting work_in_progress
in sugov_update_commit() and clearing it in sugov_work() will still
be dropped due to the work_in_progress check in sugov_update_single().
To close that window, rearrange the code so as to acquire the update
lock around the deferred update branch in sugov_update_single()
and drop the work_in_progress check from it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Currently there is a chance of a schedutil cpufreq update request to be
dropped if there is a pending update request. This pending request can
be delayed if there is a scheduling delay of the irq_work and the wake
up of the schedutil governor kthread.
A very bad scenario is when a schedutil request was already just made,
such as to reduce the CPU frequency, then a newer request to increase
CPU frequency (even sched deadline urgent frequency increase requests)
can be dropped, even though the rate limits suggest that its Ok to
process a request. This is because of the way the work_in_progress flag
is used.
This patch improves the situation by allowing new requests to happen
even though the old one is still being processed. Note that in this
approach, if an irq_work was already issued, we just update next_freq
and don't bother to queue another request so there's no extra work being
done to make this happen.
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This routine checks if the CPU running this code belongs to the policy
of the target CPU or if not, can it do remote DVFS for it remotely. But
the current name of it implies as if it is only about doing remote
updates.
Rename it to make it more relevant.
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The iowait boosting code has been recently updated to add a progressive
boosting behavior which allows to be less aggressive in boosting tasks
doing only sporadic IO operations, thus being more energy efficient for
example on mobile platforms.
The current code is now however a bit convoluted. Some functionalities
(e.g. iowait boost reset) are replicated in different paths and their
documentation is slightly misaligned.
Let's cleanup the code by consolidating all the IO wait boosting related
functionality within within few dedicated functions and better define
their role:
- sugov_iowait_boost: set/increase the IO wait boost of a CPU
- sugov_iowait_apply: apply/reduce the IO wait boost of a CPU
Both these two function are used at every sugov update and they make
use of a unified IO wait boost reset policy provided by:
- sugov_iowait_reset: reset/disable the IO wait boost of a CPU
if a CPU is not updated for more then one tick
This makes possible a cleaner and more self-contained design for the IO
wait boosting code since the rest of the sugov update routines, both for
single and shared frequency domains, follow the same template:
/* Configure IO boost, if required */
sugov_iowait_boost()
/* Return here if freq change is in progress or throttled */
/* Collect and aggregate utilization information */
sugov_get_util()
sugov_aggregate_util()
/*
* Add IO boost, if currently enabled, on top of the aggregated
* utilization value
*/
sugov_iowait_apply()
As a extra bonus, let's also add the documentation for the new
functions and better align the in-code documentation.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
A more energy efficient update of the IO wait boosting mechanism has
been introduced in:
commit a5a0809bc5 ("cpufreq: schedutil: Make iowait boost more energy efficient")
where the boost value is expected to be:
- doubled at each successive wakeup from IO
staring from the minimum frequency supported by a CPU
- reset when a CPU is not updated for more then one tick
by either disabling the IO wait boost or resetting its value to the
minimum frequency if this new update requires an IO boost.
This approach is supposed to "ignore" boosting for sporadic wakeups from
IO, while still getting the frequency boosted to the maximum to benefit
long sequence of wakeup from IO operations.
However, these assumptions are not always satisfied.
For example, when an IO boosted CPU enters idle for more the one tick
and then wakes up after an IO wait, since in sugov_set_iowait_boost() we
first check the IOWAIT flag, we keep doubling the iowait boost instead
of restarting from the minimum frequency value.
This misbehavior could happen mainly on non-shared frequency domains,
thus defeating the energy efficiency optimization, but it can also
happen on shared frequency domain systems.
Let fix this issue in sugov_set_iowait_boost() by:
- first check the IO wait boost reset conditions
to eventually reset the boost value
- then applying the correct IO boost value
if required by the caller
Fixes: a5a0809bc5 (cpufreq: schedutil: Make iowait boost more energy efficient)
Reported-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Since the grub_reclaim() function can be made static, make it so.
Silences the following GCC warning (W=1):
kernel/sched/deadline.c:1120:5: warning: no previous prototype for ‘grub_reclaim’ [-Wmissing-prototypes]
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180516200902.959-1-malat@debian.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In the following commit:
6b55c9654f ("sched/debug: Move print_cfs_rq() declaration to kernel/sched/sched.h")
the print_cfs_rq() prototype was added to <kernel/sched/sched.h>,
right next to the prototypes for print_cfs_stats(), print_rt_stats()
and print_dl_stats().
Finish this previous commit and also move related prototypes for
print_rt_rq() and print_dl_rq().
Remove existing extern declarations now that they not needed anymore.
Silences the following GCC warning, triggered by W=1:
kernel/sched/debug.c:573:6: warning: no previous prototype for ‘print_rt_rq’ [-Wmissing-prototypes]
kernel/sched/debug.c:603:6: warning: no previous prototype for ‘print_dl_rq’ [-Wmissing-prototypes]
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180516195348.30426-1-malat@debian.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
- Updates to the handling of expedited grace periods, perhaps most
notably parallelizing their initialization. Other changes
include fixes from Boqun Feng.
- Miscellaneous fixes. These include an nvme fix from Nitzan Carmi
that I am carrying because it depends on a new SRCU function
cleanup_srcu_struct_quiesced(). This branch also includes fixes
from Byungchul Park and Yury Norov.
- Updates to reduce lock contention in the rcu_node combining tree.
These are in preparation for the consolidation of RCU-bh,
RCU-preempt, and RCU-sched into a single flavor, which was
requested by Linus Torvalds in response to a security flaw
whose root cause included confusion between the multiple flavors
of RCU.
- Torture-test updates that save their users some time and effort.
Conflicts:
drivers/nvme/host/core.c
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Variants of proc_create{,_data} that directly take a struct seq_operations
argument and drastically reduces the boilerplate code in the callers.
All trivial callers converted over.
Signed-off-by: Christoph Hellwig <hch@lst.de>
The cond_resched_softirq() macro is not used anywhere in mainline, so
this commit simplifies the kernel by eliminating it.
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Tested-by: Nicholas Piggin <npiggin@gmail.com>
The schedutil driver sets sg_policy->next_freq to UINT_MAX on certain
occasions to discard the cached value of next freq:
- In sugov_start(), when the schedutil governor is started for a group
of CPUs.
- And whenever we need to force a freq update before rate-limit
duration, which happens when:
- there is an update in cpufreq policy limits.
- Or when the utilization of DL scheduling class increases.
In return, get_next_freq() doesn't return a cached next_freq value but
recalculates the next frequency instead.
But having special meaning for a particular value of frequency makes the
code less readable and error prone. We recently fixed a bug where the
UINT_MAX value was considered as valid frequency in
sugov_update_single().
All we need is a flag which can be used to discard the value of
sg_policy->next_freq and we already have need_freq_update for that. Lets
reuse it instead of setting next_freq to UINT_MAX.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This reverts commit e2cabe48c2.
Lifting the restriction that the sugov kthread is bound to the
policy->related_cpus for a system with a slow switching cpufreq driver,
which is able to perform DVFS from any cpu (e.g. cpufreq-dt), is not
only not beneficial it also harms Enery-Aware Scheduling (EAS) on
systems with asymmetric cpu capacities (e.g. Arm big.LITTLE).
The sugov kthread which does the update for the little cpus could
potentially run on a big cpu. It could prevent that the big cluster goes
into deeper idle states although all the tasks are running on the little
cluster.
Example: hikey960 w/ 4.16.0-rc6-+
Arm big.LITTLE with per-cluster DVFS
root@h960:~# cat /proc/cpuinfo | grep "^CPU part"
CPU part : 0xd03 (Cortex-A53, little cpu)
CPU part : 0xd03
CPU part : 0xd03
CPU part : 0xd03
CPU part : 0xd09 (Cortex-A73, big cpu)
CPU part : 0xd09
CPU part : 0xd09
CPU part : 0xd09
root@h960:/sys/devices/system/cpu/cpufreq# ls
policy0 policy4 schedutil
root@h960:/sys/devices/system/cpu/cpufreq# cat policy*/related_cpus
0 1 2 3
4 5 6 7
(1) w/o the revert:
root@h960:~# ps -eo pid,class,rtprio,pri,psr,comm | awk 'NR == 1 ||
/sugov/'
PID CLS RTPRIO PRI PSR COMMAND
1489 #6 0 140 1 sugov:0
1490 #6 0 140 0 sugov:4
The sugov kthread sugov:4 responsible for policy4 runs on cpu0. (In this
case both sugov kthreads run on little cpus).
cross policy (cluster) remote callback example:
...
migration/1-14 [001] enqueue_task_fair: this_cpu=1 cpu_of(rq)=5
migration/1-14 [001] sugov_update_shared: this_cpu=1 sg_cpu->cpu=5
sg_cpu->sg_policy->policy->related_cpus=4-7
sugov:4-1490 [000] sugov_work: this_cpu=0
sg_cpu->sg_policy->policy->related_cpus=4-7
...
The remote callback (this_cpu=1, target_cpu=5) is executed on cpu=0.
(2) w/ the revert:
root@h960:~# ps -eo pid,class,rtprio,pri,psr,comm | awk 'NR == 1 ||
/sugov/'
PID CLS RTPRIO PRI PSR COMMAND
1491 #6 0 140 2 sugov:0
1492 #6 0 140 4 sugov:4
The sugov kthread sugov:4 responsible for policy4 runs on cpu4.
cross policy (cluster) remote callback example:
...
migration/1-14 [001] enqueue_task_fair: this_cpu=1 cpu_of(rq)=7
migration/1-14 [001] sugov_update_shared: this_cpu=1 sg_cpu->cpu=7
sg_cpu->sg_policy->policy->related_cpus=4-7
sugov:4-1492 [004] sugov_work: this_cpu=4
sg_cpu->sg_policy->policy->related_cpus=4-7
...
The remote callback (this_cpu=1, target_cpu=7) is executed on cpu=4.
Now the sugov kthread executes again on the policy (cluster) for which
the Operating Performance Point (OPP) should be changed.
It avoids the problem that an otherwise idle policy (cluster) is running
schedutil (the sugov kthread) for another one.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In the following commit:
247f2f6f3c ("sched/core: Don't schedule threads on pre-empted vCPUs")
... we distinguish between idle_cpu() when the vCPU is not running for
scheduling threads.
However, the idle_cpu() function is used in other places for
actually checking whether the state of the CPU is idle or not.
Hence split the use of that function based on the desired return value,
by introducing the available_idle_cpu() function.
This fixes a (slight) regression in that initial vCPU commit, because
some code paths (like the load-balancer) don't care and shouldn't care
if the vCPU is preempted or not, they just want to know if there's any
tasks on the CPU.
Signed-off-by: Rohit Jain <rohit.k.jain@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dhaval.giani@oracle.com
Cc: linux-kernel@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: steven.sistare@oracle.com
Cc: subhra.mazumdar@oracle.com
Link: http://lkml.kernel.org/r/1525883988-10356-1-git-send-email-rohit.k.jain@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Threads share an address space and each can change the protections of the
same address space to trap NUMA faults. This is redundant and potentially
counter-productive as any thread doing the update will suffice. Potentially
only one thread is required but that thread may be idle or it may not have
any locality concerns and pick an unsuitable scan rate.
This patch uses independent scan period but they are staggered based on
the number of address space users when the thread is created. The intent
is that threads will avoid scanning at the same time and have a chance
to adapt their scan rate later if necessary. This reduces the total scan
activity early in the lifetime of the threads.
The different in headline performance across a range of machines and
workloads is marginal but the system CPU usage is reduced as well as overall
scan activity. The following is the time reported by NAS Parallel Benchmark
using unbound openmp threads and a D size class:
4.17.0-rc1 4.17.0-rc1
vanilla stagger-v1r1
Time bt.D 442.77 ( 0.00%) 419.70 ( 5.21%)
Time cg.D 171.90 ( 0.00%) 180.85 ( -5.21%)
Time ep.D 33.10 ( 0.00%) 32.90 ( 0.60%)
Time is.D 9.59 ( 0.00%) 9.42 ( 1.77%)
Time lu.D 306.75 ( 0.00%) 304.65 ( 0.68%)
Time mg.D 54.56 ( 0.00%) 52.38 ( 4.00%)
Time sp.D 1020.03 ( 0.00%) 903.77 ( 11.40%)
Time ua.D 400.58 ( 0.00%) 386.49 ( 3.52%)
Note it's not a universal win but we have no prior knowledge of which
thread matters but the number of threads created often exceeds the size
of the node when the threads are not bound. However, there is a reducation
of overall system CPU usage:
4.17.0-rc1 4.17.0-rc1
vanilla stagger-v1r1
sys-time-bt.D 48.78 ( 0.00%) 48.22 ( 1.15%)
sys-time-cg.D 25.31 ( 0.00%) 26.63 ( -5.22%)
sys-time-ep.D 1.65 ( 0.00%) 0.62 ( 62.42%)
sys-time-is.D 40.05 ( 0.00%) 24.45 ( 38.95%)
sys-time-lu.D 37.55 ( 0.00%) 29.02 ( 22.72%)
sys-time-mg.D 47.52 ( 0.00%) 34.92 ( 26.52%)
sys-time-sp.D 119.01 ( 0.00%) 109.05 ( 8.37%)
sys-time-ua.D 51.52 ( 0.00%) 45.13 ( 12.40%)
NUMA scan activity is also reduced:
NUMA alloc local 1042828 1342670
NUMA base PTE updates 140481138 93577468
NUMA huge PMD updates 272171 180766
NUMA page range updates 279832690 186129660
NUMA hint faults 1395972 1193897
NUMA hint local faults 877925 855053
NUMA hint local percent 62 71
NUMA pages migrated 12057909 9158023
Similar observations are made for other thread-intensive workloads. System
CPU usage is lower even though the headline gains in performance tend to be
small. For example, specjbb 2005 shows almost no difference in performance
but scan activity is reduced by a third on a 4-socket box. I didn't find
a workload (thread intensive or otherwise) that suffered badly.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20180504154109.mvrha2qo5wdl65vr@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86/pti updates from Thomas Gleixner:
"A mixed bag of fixes and updates for the ghosts which are hunting us.
The scheduler fixes have been pulled into that branch to avoid
conflicts.
- A set of fixes to address a khread_parkme() race which caused lost
wakeups and loss of state.
- A deadlock fix for stop_machine() solved by moving the wakeups
outside of the stopper_lock held region.
- A set of Spectre V1 array access restrictions. The possible
problematic spots were discuvered by Dan Carpenters new checks in
smatch.
- Removal of an unused file which was forgotten when the rest of that
functionality was removed"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/vdso: Remove unused file
perf/x86/cstate: Fix possible Spectre-v1 indexing for pkg_msr
perf/x86/msr: Fix possible Spectre-v1 indexing in the MSR driver
perf/x86: Fix possible Spectre-v1 indexing for x86_pmu::event_map()
perf/x86: Fix possible Spectre-v1 indexing for hw_perf_event cache_*
perf/core: Fix possible Spectre-v1 indexing for ->aux_pages[]
sched/autogroup: Fix possible Spectre-v1 indexing for sched_prio_to_weight[]
sched/core: Fix possible Spectre-v1 indexing for sched_prio_to_weight[]
sched/core: Introduce set_special_state()
kthread, sched/wait: Fix kthread_parkme() completion issue
kthread, sched/wait: Fix kthread_parkme() wait-loop
sched/fair: Fix the update of blocked load when newly idle
stop_machine, sched: Fix migrate_swap() vs. active_balance() deadlock
Pull scheduler fix from Thomas Gleixner:
"Revert the new NUMA aware placement approach which turned out to
create more problems than it solved"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Revert "sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine()"
This reverts commit 7347fc87df.
Srikar Dronamra pointed out that while the commit in question did show
a performance improvement on ppc64, it did so at the cost of disabling
active CPU migration by automatic NUMA balancing which was not the intent.
The issue was that a serious flaw in the logic failed to ever active balance
if SD_WAKE_AFFINE was disabled on scheduler domains. Even when it's enabled,
the logic is still bizarre and against the original intent.
Investigation showed that fixing the patch in either the way he suggested,
using the correct comparison for jiffies values or introducing a new
numa_migrate_deferred variable in task_struct all perform similarly to a
revert with a mix of gains and losses depending on the workload, machine
and socket count.
The original intent of the commit was to handle a problem whereby
wake_affine, idle balancing and automatic NUMA balancing disagree on the
appropriate placement for a task. This was particularly true for cases where
a single task was a massive waker of tasks but where wake_wide logic did
not apply. This was particularly noticeable when a futex (a barrier) woke
all worker threads and tried pulling the wakees to the waker nodes. In that
specific case, it could be handled by tuning MPI or openMP appropriately,
but the behavior is not illogical and was worth attempting to fix. However,
the approach was wrong. Given that we're at rc4 and a fix is not obvious,
it's better to play safe, revert this commit and retry later.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: efault@gmx.de
Cc: ggherdovich@suse.cz
Cc: hpa@zytor.com
Cc: matt@codeblueprint.co.uk
Cc: mpe@ellerman.id.au
Link: http://lkml.kernel.org/r/20180509163115.6fnnyeg4vdm2ct4v@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If the next_freq field of struct sugov_policy is set to UINT_MAX,
it shouldn't be used for updating the CPU frequency (this is a
special "invalid" value), but after commit b7eaf1aab9 (cpufreq:
schedutil: Avoid reducing frequency of busy CPUs prematurely) it
may be passed as the new frequency to sugov_update_commit() in
sugov_update_single().
Fix that by adding an extra check for the special UINT_MAX value
of next_freq to sugov_update_single().
Fixes: b7eaf1aab9 (cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely)
Reported-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.12+ <stable@vger.kernel.org> # 4.12+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
After commit 794a56ebd9 (sched/cpufreq: Change the worker kthread to
SCHED_DEADLINE) schedutil kthreads are "ignored" for a clock frequency
selection point of view, so the potential corner case for RT tasks is not
possible at all now.
Remove the stale comment mentioning it.
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> kernel/sched/core.c:6921 cpu_weight_nice_write_s64() warn: potential spectre issue 'sched_prio_to_weight'
Userspace controls @nice, so sanitize the value before using it to
index an array.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Call sync_entity_load_avg() directly from find_idlest_cpu() instead of
select_task_rq_fair(), as that's where we need to use task's utilization
value. And call sync_entity_load_avg() only after making sure sched
domain spans over one of the allowed CPUs for the task.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/cd019d1753824c81130eae7b43e2bbcec47cc1ad.1524738578.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Rearrange select_task_rq_fair() a bit to avoid executing some
conditional statements in few specific code-paths. That gets rid of the
goto as well.
This shouldn't result in any functional changes.
Tested-by: Rohit Jain <rohit.k.jain@oracle.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/20831b8d237bf3a20e4e328286f678b425ff04c9.1524738578.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Gaurav reported a perceived problem with TASK_PARKED, which turned out
to be a broken wait-loop pattern in __kthread_parkme(), but the
reported issue can (and does) in fact happen for states that do not do
condition based sleeps.
When the 'current->state = TASK_RUNNING' store of a previous
(concurrent) try_to_wake_up() collides with the setting of a 'special'
sleep state, we can loose the sleep state.
Normal condition based wait-loops are immune to this problem, but for
sleep states that are not condition based are subject to this problem.
There already is a fix for TASK_DEAD. Abstract that and also apply it
to TASK_STOPPED and TASK_TRACED, both of which are also without
condition based wait-loop.
Reported-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Even with the wait-loop fixed, there is a further issue with
kthread_parkme(). Upon hotplug, when we do takedown_cpu(),
smpboot_park_threads() can return before all those threads are in fact
blocked, due to the placement of the complete() in __kthread_parkme().
When that happens, sched_cpu_dying() -> migrate_tasks() can end up
migrating such a still runnable task onto another CPU.
Normally the task will have hit schedule() and gone to sleep by the
time we do kthread_unpark(), which will then do __kthread_bind() to
re-bind the task to the correct CPU.
However, when we loose the initial TASK_PARKED store to the concurrent
wakeup issue described previously, do the complete(), get migrated, it
is possible to either:
- observe kthread_unpark()'s clearing of SHOULD_PARK and terminate
the park and set TASK_RUNNING, or
- __kthread_bind()'s wait_task_inactive() to observe the competing
TASK_RUNNING store.
Either way the WARN() in __kthread_bind() will trigger and fail to
correctly set the CPU affinity.
Fix this by only issuing the complete() when the kthread has scheduled
out. This does away with all the icky 'still running' nonsense.
The alternative is to promote TASK_PARKED to a special state, this
guarantees wait_task_inactive() cannot observe a 'stale' TASK_RUNNING
and we'll end up doing the right thing, but this preserves the whole
icky business of potentially migating the still runnable thing.
Reported-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With commit:
31e77c93e4 ("sched/fair: Update blocked load when newly idle")
... we release the rq->lock when updating blocked load of idle CPUs.
This opens a time window during which another CPU can add a task to this
CPU's cfs_rq.
The check for newly added task of idle_balance() is not in the common path.
Move the out label to include this check.
Reported-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 31e77c93e4 ("sched/fair: Update blocked load when newly idle")
Link: http://lkml.kernel.org/r/20180426103133.GA6953@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler fixes from Thomas Gleixner:
"A few scheduler fixes:
- Prevent a bogus warning vs. runqueue clock update flags in
do_sched_rt_period_timer()
- Simplify the helper functions which handle requests for skipping
the runqueue clock updat.
- Do not unlock the tunables mutex in the error path of the cpu
frequency scheduler utils. Its not held.
- Enforce proper alignement for 'struct util_est' in sched_avg to
prevent a misalignment fault on IA64"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/core: Force proper alignment of 'struct util_est'
sched/core: Simplify helpers for rq clock update skip requests
sched/rt: Fix rq->clock_update_flags < RQCF_ACT_SKIP warning
sched/cpufreq/schedutil: Fix error path mutex unlock
- Rework the idle loop in order to prevent CPUs from spending too
much time in shallow idle states by making it stop the scheduler
tick before putting the CPU into an idle state only if the idle
duration predicted by the idle governor is long enough. That
required the code to be reordered to invoke the idle governor
before stopping the tick, among other things (Rafael Wysocki,
Frederic Weisbecker, Arnd Bergmann).
- Add the missing description of the residency sysfs attribute to
the cpuidle documentation (Prashanth Prakash).
- Finalize the cpufreq cleanup moving frequency table validation
from drivers to the core (Viresh Kumar).
- Fix a clock leak regression in the armada-37xx cpufreq driver
(Gregory Clement).
- Fix the initialization of the CPU performance data structures
for shared policies in the CPPC cpufreq driver (Shunyong Yang).
- Clean up the ti-cpufreq, intel_pstate and CPPC cpufreq drivers
a bit (Viresh Kumar, Rafael Wysocki).
- Mark the expected switch fall-throughs in the PM QoS core (Gustavo
Silva).
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2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=Pnk4
-----END PGP SIGNATURE-----
Merge tag 'pm-4.17-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management updates from Rafael Wysocki:
"These include one big-ticket item which is the rework of the idle loop
in order to prevent CPUs from spending too much time in shallow idle
states. It reduces idle power on some systems by 10% or more and may
improve performance of workloads in which the idle loop overhead
matters. This has been in the works for several weeks and it has been
tested and reviewed quite thoroughly.
Also included are changes that finalize the cpufreq cleanup moving
frequency table validation from drivers to the core, a few fixes and
cleanups of cpufreq drivers, a cpuidle documentation update and a PM
QoS core update to mark the expected switch fall-throughs in it.
Specifics:
- Rework the idle loop in order to prevent CPUs from spending too
much time in shallow idle states by making it stop the scheduler
tick before putting the CPU into an idle state only if the idle
duration predicted by the idle governor is long enough.
That required the code to be reordered to invoke the idle governor
before stopping the tick, among other things (Rafael Wysocki,
Frederic Weisbecker, Arnd Bergmann).
- Add the missing description of the residency sysfs attribute to the
cpuidle documentation (Prashanth Prakash).
- Finalize the cpufreq cleanup moving frequency table validation from
drivers to the core (Viresh Kumar).
- Fix a clock leak regression in the armada-37xx cpufreq driver
(Gregory Clement).
- Fix the initialization of the CPU performance data structures for
shared policies in the CPPC cpufreq driver (Shunyong Yang).
- Clean up the ti-cpufreq, intel_pstate and CPPC cpufreq drivers a
bit (Viresh Kumar, Rafael Wysocki).
- Mark the expected switch fall-throughs in the PM QoS core (Gustavo
Silva)"
* tag 'pm-4.17-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (23 commits)
tick-sched: avoid a maybe-uninitialized warning
cpufreq: Drop cpufreq_table_validate_and_show()
cpufreq: SCMI: Don't validate the frequency table twice
cpufreq: CPPC: Initialize shared perf capabilities of CPUs
cpufreq: armada-37xx: Fix clock leak
cpufreq: CPPC: Don't set transition_latency
cpufreq: ti-cpufreq: Use builtin_platform_driver()
cpufreq: intel_pstate: Do not include debugfs.h
PM / QoS: mark expected switch fall-throughs
cpuidle: Add definition of residency to sysfs documentation
time: hrtimer: Use timerqueue_iterate_next() to get to the next timer
nohz: Avoid duplication of code related to got_idle_tick
nohz: Gather tick_sched booleans under a common flag field
cpuidle: menu: Avoid selecting shallow states with stopped tick
cpuidle: menu: Refine idle state selection for running tick
sched: idle: Select idle state before stopping the tick
time: hrtimer: Introduce hrtimer_next_event_without()
time: tick-sched: Split tick_nohz_stop_sched_tick()
cpuidle: Return nohz hint from cpuidle_select()
jiffies: Introduce USER_TICK_USEC and redefine TICK_USEC
...
In order to address the issue with short idle duration predictions
by the idle governor after the scheduler tick has been stopped,
reorder the code in cpuidle_idle_call() so that the governor idle
state selection runs before tick_nohz_idle_go_idle() and use the
"nohz" hint returned by cpuidle_select() to decide whether or not
to stop the tick.
This isn't straightforward, because menu_select() invokes
tick_nohz_get_sleep_length() to get the time to the next timer
event and the number returned by the latter comes from
__tick_nohz_idle_stop_tick(). Fortunately, however, it is possible
to compute that number without actually stopping the tick and with
the help of the existing code.
Namely, tick_nohz_get_sleep_length() can be made call
tick_nohz_next_event(), introduced earlier, to get the time to the
next non-highres timer event. If that happens, tick_nohz_next_event()
need not be called by __tick_nohz_idle_stop_tick() again.
If it turns out that the scheduler tick cannot be stopped going
forward or the next timer event is too close for the tick to be
stopped, tick_nohz_get_sleep_length() can simply return the time to
the next event currently programmed into the corresponding clock
event device.
In addition to knowing the return value of tick_nohz_next_event(),
however, tick_nohz_get_sleep_length() needs to know the time to the
next highres timer event, but with the scheduler tick timer excluded,
which can be computed with the help of hrtimer_get_next_event().
That minimum of that number and the tick_nohz_next_event() return
value is the total time to the next timer event with the assumption
that the tick will be stopped. It can be returned to the idle
governor which can use it for predicting idle duration (under the
assumption that the tick will be stopped) and deciding whether or
not it makes sense to stop the tick before putting the CPU into the
selected idle state.
With the above, the sleep_length field in struct tick_sched is not
necessary any more, so drop it.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=199227
Reported-by: Doug Smythies <dsmythies@telus.net>
Reported-by: Thomas Ilsche <thomas.ilsche@tu-dresden.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Add a new pointer argument to cpuidle_select() and to the ->select
cpuidle governor callback to allow a boolean value indicating
whether or not the tick should be stopped before entering the
selected state to be returned from there.
Make the ladder governor ignore that pointer (to preserve its
current behavior) and make the menu governor return 'false" through
it if:
(1) the idle exit latency is constrained at 0, or
(2) the selected state is a polling one, or
(3) the expected idle period duration is within the tick period
range.
In addition to that, the correction factor computations in the menu
governor need to take the possibility that the tick may not be
stopped into account to avoid artificially small correction factor
values. To that end, add a mechanism to record tick wakeups, as
suggested by Peter Zijlstra, and use it to modify the menu_update()
behavior when tick wakeup occurs. Namely, if the CPU is woken up by
the tick and the return value of tick_nohz_get_sleep_length() is not
within the tick boundary, the predicted idle duration is likely too
short, so make menu_update() try to compensate for that by updating
the governor statistics as though the CPU was idle for a long time.
Since the value returned through the new argument pointer of
cpuidle_select() is not used by its caller yet, this change by
itself is not expected to alter the functionality of the code.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
KASAN splats indicate that in some cases we free a live mm, then
continue to access it, with potentially disastrous results. This is
likely due to a mismatched mmdrop() somewhere in the kernel, but so far
the culprit remains elusive.
Let's have __mmdrop() verify that the mm isn't live for the current
task, similar to the existing check for init_mm. This way, we can catch
this class of issue earlier, and without requiring KASAN.
Currently, idle_task_exit() leaves active_mm stale after it switches to
init_mm. This isn't harmful, but will trigger the new assertions, so we
must adjust idle_task_exit() to update active_mm.
Link: http://lkml.kernel.org/r/20180312140103.19235-1-mark.rutland@arm.com
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make cpuidle_idle_call() decide whether or not to stop the tick.
First, the cpuidle_enter_s2idle() path deals with the tick (and with
the entire timekeeping for that matter) by itself and it doesn't need
the tick to be stopped beforehand.
Second, to address the issue with short idle duration predictions
by the idle governor after the tick has been stopped, it will be
necessary to change the ordering of cpuidle_select() with respect
to tick_nohz_idle_stop_tick(). To prepare for that, put a
tick_nohz_idle_stop_tick() call in the same branch in which
cpuidle_select() is called.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Push the decision whether or not to stop the tick somewhat deeper
into the idle loop.
Stopping the tick upfront leads to unpleasant outcomes in case the
idle governor doesn't agree with the nohz code on the duration of the
upcoming idle period. Specifically, if the tick has been stopped and
the idle governor predicts short idle, the situation is bad regardless
of whether or not the prediction is accurate. If it is accurate, the
tick has been stopped unnecessarily which means excessive overhead.
If it is not accurate, the CPU is likely to spend too much time in
the (shallow, because short idle has been predicted) idle state
selected by the governor [1].
As the first step towards addressing this problem, change the code
to make the tick stopping decision inside of the loop in do_idle().
In particular, do not stop the tick in the cpu_idle_poll() code path.
Also don't do that in tick_nohz_irq_exit() which doesn't really have
enough information on whether or not to stop the tick.
Link: https://marc.info/?l=linux-pm&m=150116085925208&w=2 # [1]
Link: https://tu-dresden.de/zih/forschung/ressourcen/dateien/projekte/haec/powernightmares.pdf
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Prepare the scheduler tick code for reworking the idle loop to
avoid stopping the tick in some cases.
The idea is to split the nohz idle entry call to decouple the idle
time stats accounting and preparatory work from the actual tick stop
code, in order to later be able to delay the tick stop once we reach
more power-knowledgeable callers.
Move away the tick_nohz_start_idle() invocation from
__tick_nohz_idle_enter(), rename the latter to
__tick_nohz_idle_stop_tick() and define tick_nohz_idle_stop_tick()
as a wrapper around it for calling it from the outside.
Make tick_nohz_idle_enter() only call tick_nohz_start_idle() instead
of calling the entire __tick_nohz_idle_enter(), add another wrapper
disabling and enabling interrupts around tick_nohz_idle_stop_tick()
and make the current callers of tick_nohz_idle_enter() call it too
to retain their current functionality.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
By renaming the functions we can get rid of the skip parameter
and have better code redability. It makes zero sense to have
things such as:
rq_clock_skip_update(rq, false)
When the skip request is in fact not going to happen. Ever. Rename
things such that we end up with:
rq_clock_skip_update(rq)
rq_clock_cancel_skipupdate(rq)
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20180404161539.nhadkff2aats74jh@linux-n805
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While running rt-tests' pi_stress program I got the following splat:
rq->clock_update_flags < RQCF_ACT_SKIP
WARNING: CPU: 27 PID: 0 at kernel/sched/sched.h:960 assert_clock_updated.isra.38.part.39+0x13/0x20
[...]
<IRQ>
enqueue_top_rt_rq+0xf4/0x150
? cpufreq_dbs_governor_start+0x170/0x170
sched_rt_rq_enqueue+0x65/0x80
sched_rt_period_timer+0x156/0x360
? sched_rt_rq_enqueue+0x80/0x80
__hrtimer_run_queues+0xfa/0x260
hrtimer_interrupt+0xcb/0x220
smp_apic_timer_interrupt+0x62/0x120
apic_timer_interrupt+0xf/0x20
</IRQ>
[...]
do_idle+0x183/0x1e0
cpu_startup_entry+0x5f/0x70
start_secondary+0x192/0x1d0
secondary_startup_64+0xa5/0xb0
We can get rid of it be the "traditional" means of adding an
update_rq_clock() call after acquiring the rq->lock in
do_sched_rt_period_timer().
The case for the RT task throttling (which this workload also hits)
can be ignored in that the skip_update call is actually bogus and
quite the contrary (the request bits are removed/reverted).
By setting RQCF_UPDATED we really don't care if the skip is happening
or not and will therefore make the assert_clock_updated() check happy.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: linux-kernel@vger.kernel.org
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20180402164954.16255-1-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull removal of in-kernel calls to syscalls from Dominik Brodowski:
"System calls are interaction points between userspace and the kernel.
Therefore, system call functions such as sys_xyzzy() or
compat_sys_xyzzy() should only be called from userspace via the
syscall table, but not from elsewhere in the kernel.
At least on 64-bit x86, it will likely be a hard requirement from
v4.17 onwards to not call system call functions in the kernel: It is
better to use use a different calling convention for system calls
there, where struct pt_regs is decoded on-the-fly in a syscall wrapper
which then hands processing over to the actual syscall function. This
means that only those parameters which are actually needed for a
specific syscall are passed on during syscall entry, instead of
filling in six CPU registers with random user space content all the
time (which may cause serious trouble down the call chain). Those
x86-specific patches will be pushed through the x86 tree in the near
future.
Moreover, rules on how data may be accessed may differ between kernel
data and user data. This is another reason why calling sys_xyzzy() is
generally a bad idea, and -- at most -- acceptable in arch-specific
code.
This patchset removes all in-kernel calls to syscall functions in the
kernel with the exception of arch/. On top of this, it cleans up the
three places where many syscalls are referenced or prototyped, namely
kernel/sys_ni.c, include/linux/syscalls.h and include/linux/compat.h"
* 'syscalls-next' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux: (109 commits)
bpf: whitelist all syscalls for error injection
kernel/sys_ni: remove {sys_,sys_compat} from cond_syscall definitions
kernel/sys_ni: sort cond_syscall() entries
syscalls/x86: auto-create compat_sys_*() prototypes
syscalls: sort syscall prototypes in include/linux/compat.h
net: remove compat_sys_*() prototypes from net/compat.h
syscalls: sort syscall prototypes in include/linux/syscalls.h
kexec: move sys_kexec_load() prototype to syscalls.h
x86/sigreturn: use SYSCALL_DEFINE0
x86: fix sys_sigreturn() return type to be long, not unsigned long
x86/ioport: add ksys_ioperm() helper; remove in-kernel calls to sys_ioperm()
mm: add ksys_readahead() helper; remove in-kernel calls to sys_readahead()
mm: add ksys_mmap_pgoff() helper; remove in-kernel calls to sys_mmap_pgoff()
mm: add ksys_fadvise64_64() helper; remove in-kernel call to sys_fadvise64_64()
fs: add ksys_fallocate() wrapper; remove in-kernel calls to sys_fallocate()
fs: add ksys_p{read,write}64() helpers; remove in-kernel calls to syscalls
fs: add ksys_truncate() wrapper; remove in-kernel calls to sys_truncate()
fs: add ksys_sync_file_range helper(); remove in-kernel calls to syscall
kernel: add ksys_setsid() helper; remove in-kernel call to sys_setsid()
kernel: add ksys_unshare() helper; remove in-kernel calls to sys_unshare()
...
Pull wait_var_event updates from Ingo Molnar:
"This introduces the new wait_var_event() API, which is a more flexible
waiting primitive than wait_on_atomic_t().
All wait_on_atomic_t() users are migrated over to the new API and
wait_on_atomic_t() is removed. The migration fixes one bug and should
result in no functional changes for the other usecases"
* 'sched-wait-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/wait: Improve __var_waitqueue() code generation
sched/wait: Remove the wait_on_atomic_t() API
sched/wait, arch/mips: Fix and convert wait_on_atomic_t() usage to the new wait_var_event() API
sched/wait, fs/ocfs2: Convert wait_on_atomic_t() usage to the new wait_var_event() API
sched/wait, fs/nfs: Convert wait_on_atomic_t() usage to the new wait_var_event() API
sched/wait, fs/fscache: Convert wait_on_atomic_t() usage to the new wait_var_event() API
sched/wait, fs/btrfs: Convert wait_on_atomic_t() usage to the new wait_var_event() API
sched/wait, fs/afs: Convert wait_on_atomic_t() usage to the new wait_var_event() API
sched/wait, drivers/media: Convert wait_on_atomic_t() usage to the new wait_var_event() API
sched/wait, drivers/drm: Convert wait_on_atomic_t() usage to the new wait_var_event() API
sched/wait: Introduce wait_var_event()
Pull scheduler updates from Ingo Molnar:
"The main scheduler changes in this cycle were:
- NUMA balancing improvements (Mel Gorman)
- Further load tracking improvements (Patrick Bellasi)
- Various NOHZ balancing cleanups and optimizations (Peter Zijlstra)
- Improve blocked load handling, in particular we can now reduce and
eventually stop periodic load updates on 'very idle' CPUs. (Vincent
Guittot)
- On isolated CPUs offload the final 1Hz scheduler tick as well, plus
related cleanups and reorganization. (Frederic Weisbecker)
- Core scheduler code cleanups (Ingo Molnar)"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (45 commits)
sched/core: Update preempt_notifier_key to modern API
sched/cpufreq: Rate limits for SCHED_DEADLINE
sched/fair: Update util_est only on util_avg updates
sched/cpufreq/schedutil: Use util_est for OPP selection
sched/fair: Use util_est in LB and WU paths
sched/fair: Add util_est on top of PELT
sched/core: Remove TASK_ALL
sched/completions: Use bool in try_wait_for_completion()
sched/fair: Update blocked load when newly idle
sched/fair: Move idle_balance()
sched/nohz: Merge CONFIG_NO_HZ_COMMON blocks
sched/fair: Move rebalance_domains()
sched/nohz: Optimize nohz_idle_balance()
sched/fair: Reduce the periodic update duration
sched/nohz: Stop NOHZ stats when decayed
sched/cpufreq: Provide migration hint
sched/nohz: Clean up nohz enter/exit
sched/fair: Update blocked load from NEWIDLE
sched/fair: Add NOHZ stats balancing
sched/fair: Restructure nohz_balance_kick()
...
Using the sched-internal do_sched_yield() helper allows us to get rid of
the sched-internal call to the sys_sched_yield() syscall.
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
This patch prevents the 'global_tunables_lock' mutex from being
unlocked before being locked. This mutex is not locked if the
sugov_kthread_create() function fails.
Signed-off-by: Jules Maselbas <jules.maselbas@arm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Redpath <chris.redpath@arm.com>
Cc: Dietmar Eggermann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Stephen Kyle <stephen.kyle@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: nd@arm.com
Link: http://lkml.kernel.org/r/20180329144301.38419-1-jules.maselbas@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler fixes from Ingo Molnar:
"Two sched debug output related fixes: a console output fix and
formatting fixes"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/debug: Adjust newlines for better alignment
sched/debug: Fix per-task line continuation for console output
When the SCHED_DEADLINE scheduling class increases the CPU utilization, it
should not wait for the rate limit, otherwise it may miss some deadline.
Tests using rt-app on Exynos5422 with up to 10 SCHED_DEADLINE tasks have
shown reductions of even 10% of deadline misses with a negligible
increase of energy consumption (measured through Baylibre Cape).
Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linux-pm@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Todd Kjos <tkjos@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/1520937340-2755-1-git-send-email-claudio@evidence.eu.com
Scheduler debug stats include newlines that display out of alignment
when prefixed by timestamps. For example, the dmesg utility:
% echo t > /proc/sysrq-trigger
% dmesg
...
[ 83.124251]
runnable tasks:
S task PID tree-key switches prio wait-time
sum-exec sum-sleep
-----------------------------------------------------------------------------------------------------------
At the same time, some syslog utilities (like rsyslog by default) don't
like the additional newlines control characters, saving lines like this
to /var/log/messages:
Mar 16 16:02:29 localhost kernel: #012runnable tasks:#012 S task PID tree-key ...
^^^^ ^^^^
Clean these up by moving newline characters to their own SEQ_printf
invocation. This leaves the /proc/sched_debug unchanged, but brings the
entire output into alignment when prefixed:
% echo t > /proc/sysrq-trigger
% dmesg
...
[ 62.410368] runnable tasks:
[ 62.410368] S task PID tree-key switches prio wait-time sum-exec sum-sleep
[ 62.410369] -----------------------------------------------------------------------------------------------------------
[ 62.410369] I kworker/u12:0 5 1932.215593 332 120 0.000000 3.621252 0.000000 0 0 /
and no escaped control characters from rsyslog in /var/log/messages:
Mar 16 16:15:06 localhost kernel: runnable tasks:
Mar 16 16:15:06 localhost kernel: S task PID tree-key ...
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1521484555-8620-3-git-send-email-joe.lawrence@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the SEQ_printf() macro prints to the console, it runs a simple
printk() without KERN_CONT "continued" line printing. The result of
this is oddly wrapped task info, for example:
% echo t > /proc/sysrq-trigger
% dmesg
...
runnable tasks:
...
[ 29.608611] I
[ 29.608613] rcu_sched 8 3252.013846 4087 120
[ 29.608614] 0.000000 29.090111 0.000000
[ 29.608615] 0 0
[ 29.608616] /
Modify SEQ_printf to use pr_cont() for expected one-line results:
% echo t > /proc/sysrq-trigger
% dmesg
...
runnable tasks:
...
[ 106.716329] S cpuhp/5 37 2006.315026 14 120 0.000000 0.496893 0.000000 0 0 /
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1521484555-8620-2-git-send-email-joe.lawrence@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since we fixed hash_64() to not suck there is no need to play games to
attempt to improve the hash value on 64-bit.
Also, since we don't use the bit value for the variables, use hash_ptr()
directly.
No change in functionality.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There are no users left (everyone got converted to wait_var_event()), remove it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As a replacement for the wait_on_atomic_t() API provide the
wait_var_event() API.
The wait_var_event() API is based on the very same hashed-waitqueue
idea, but doesn't care about the type (atomic_t) or the specific
condition (atomic_read() == 0). IOW. it's much more widely
applicable/flexible.
It shares all the benefits/disadvantages of a hashed-waitqueue
approach with the existing wait_on_atomic_t/wait_on_bit() APIs.
The API is modeled after the existing wait_event() API, but instead of
taking a wait_queue_head, it takes an address. This addresses is
hashed to obtain a wait_queue_head from the bit_wait_table.
Similar to the wait_event() API, it takes a condition expression as
second argument and will wait until this expression becomes true.
The following are (mostly) identical replacements:
wait_on_atomic_t(&my_atomic, atomic_t_wait, TASK_UNINTERRUPTIBLE);
wake_up_atomic_t(&my_atomic);
wait_var_event(&my_atomic, !atomic_read(&my_atomic));
wake_up_var(&my_atomic);
The only difference is that wake_up_var() is an unconditional wakeup
and doesn't check the previously hard-coded (atomic_read() == 0)
condition here. This is of little concequence, since most callers are
already conditional on atomic_dec_and_test() and the ones that are
not, are trivial to make so.
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The estimated utilization of a task is currently updated every time the
task is dequeued. However, to keep overheads under control, PELT signals
are effectively updated at maximum once every 1ms.
Thus, for really short running tasks, it can happen that their util_avg
value has not been updates since their last enqueue. If such tasks are
also frequently running tasks (e.g. the kind of workload generated by
hackbench) it can also happen that their util_avg is updated only every
few activations.
This means that updating util_est at every dequeue potentially introduces
not necessary overheads and it's also conceptually wrong if the util_avg
signal has never been updated during a task activation.
Let's introduce a throttling mechanism on task's util_est updates
to sync them with util_avg updates. To make the solution memory
efficient, both in terms of space and load/store operations, we encode a
synchronization flag into the LSB of util_est.enqueued.
This makes util_est an even values only metric, which is still
considered good enough for its purpose.
The synchronization bit is (re)set by __update_load_avg_se() once the
PELT signal of a task has been updated during its last activation.
Such a throttling mechanism allows to keep under control util_est
overheads in the wakeup hot path, thus making it a suitable mechanism
which can be enabled also on high-intensity workload systems.
Thus, this now switches on by default the estimation utilization
scheduler feature.
Suggested-by: Chris Redpath <chris.redpath@arm.com>
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@android.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20180309095245.11071-5-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When schedutil looks at the CPU utilization, the current PELT value for
that CPU is returned straight away. In certain scenarios this can have
undesired side effects and delays on frequency selection.
For example, since the task utilization is decayed at wakeup time, a
long sleeping big task newly enqueued does not add immediately a
significant contribution to the target CPU. This introduces some latency
before schedutil will be able to detect the best frequency required by
that task.
Moreover, the PELT signal build-up time is a function of the current
frequency, because of the scale invariant load tracking support. Thus,
starting from a lower frequency, the utilization build-up time will
increase even more and further delays the selection of the actual
frequency which better serves the task requirements.
In order to reduce these kind of latencies, we integrate the usage
of the CPU's estimated utilization in the sugov_get_util function.
This allows to properly consider the expected utilization of a CPU which,
for example, has just got a big task running after a long sleep period.
Ultimately this allows to select the best frequency to run a task
right after its wake-up.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Muckle <smuckle@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@android.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/20180309095245.11071-4-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the scheduler looks at the CPU utilization, the current PELT value
for a CPU is returned straight away. In certain scenarios this can have
undesired side effects on task placement.
For example, since the task utilization is decayed at wakeup time, when
a long sleeping big task is enqueued it does not add immediately a
significant contribution to the target CPU.
As a result we generate a race condition where other tasks can be placed
on the same CPU while it is still considered relatively empty.
In order to reduce this kind of race conditions, this patch introduces the
required support to integrate the usage of the CPU's estimated utilization
in the wakeup path, via cpu_util_wake(), as well as in the load-balance
path, via cpu_util() which is used by update_sg_lb_stats().
The estimated utilization of a CPU is defined to be the maximum between
its PELT's utilization and the sum of the estimated utilization (at
previous dequeue time) of all the tasks currently RUNNABLE on that CPU.
This allows to properly represent the spare capacity of a CPU which, for
example, has just got a big task running since a long sleep period.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@android.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20180309095245.11071-3-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The util_avg signal computed by PELT is too variable for some use-cases.
For example, a big task waking up after a long sleep period will have its
utilization almost completely decayed. This introduces some latency before
schedutil will be able to pick the best frequency to run a task.
The same issue can affect task placement. Indeed, since the task
utilization is already decayed at wakeup, when the task is enqueued in a
CPU, this can result in a CPU running a big task as being temporarily
represented as being almost empty. This leads to a race condition where
other tasks can be potentially allocated on a CPU which just started to run
a big task which slept for a relatively long period.
Moreover, the PELT utilization of a task can be updated every [ms], thus
making it a continuously changing value for certain longer running
tasks. This means that the instantaneous PELT utilization of a RUNNING
task is not really meaningful to properly support scheduler decisions.
For all these reasons, a more stable signal can do a better job of
representing the expected/estimated utilization of a task/cfs_rq.
Such a signal can be easily created on top of PELT by still using it as
an estimator which produces values to be aggregated on meaningful
events.
This patch adds a simple implementation of util_est, a new signal built on
top of PELT's util_avg where:
util_est(task) = max(task::util_avg, f(task::util_avg@dequeue))
This allows to remember how big a task has been reported by PELT in its
previous activations via f(task::util_avg@dequeue), which is the new
_task_util_est(struct task_struct*) function added by this patch.
If a task should change its behavior and it runs longer in a new
activation, after a certain time its util_est will just track the
original PELT signal (i.e. task::util_avg).
The estimated utilization of cfs_rq is defined only for root ones.
That's because the only sensible consumer of this signal are the
scheduler and schedutil when looking for the overall CPU utilization
due to FAIR tasks.
For this reason, the estimated utilization of a root cfs_rq is simply
defined as:
util_est(cfs_rq) = max(cfs_rq::util_avg, cfs_rq::util_est::enqueued)
where:
cfs_rq::util_est::enqueued = sum(_task_util_est(task))
for each RUNNABLE task on that root cfs_rq
It's worth noting that the estimated utilization is tracked only for
objects of interests, specifically:
- Tasks: to better support tasks placement decisions
- root cfs_rqs: to better support both tasks placement decisions as
well as frequencies selection
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@android.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20180309095245.11071-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull cgroup fixes from Tejun Heo:
"Two commits to fix the following subtle cgroup2 behavior bugs:
- cpu.max was rejecting config when it shouldn't
- thread mode enable was allowed when it shouldn't"
* 'for-4.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: fix rule checking for threaded mode switching
sched, cgroup: Don't reject lower cpu.max on ancestors
Since the return type of the function is bool, the internal
'ret' variable should be bool too.
Signed-off-by: Gaurav Jindal<gauravjindal1104@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180221125407.GA14292@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When NEWLY_IDLE load balance is not triggered, we might need to update the
blocked load anyway. We can kick an ilb so an idle CPU will take care of
updating blocked load or we can try to update them locally before entering
idle. In the latter case, we reuse part of the nohz_idle_balance.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: brendan.jackman@arm.com
Cc: dietmar.eggemann@arm.com
Cc: morten.rasmussen@foss.arm.com
Cc: valentin.schneider@arm.com
Link: http://lkml.kernel.org/r/1518622006-16089-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We're going to want to call nohz_idle_balance() or parts thereof from
idle_balance(). Since we already have a forward declaration of
idle_balance() move it down such that it's below nohz_idle_balance()
avoiding the need for a forward declaration for that.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that we have two back-to-back NO_HZ_COMMON blocks, merge them.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This pure code movement results in two #ifdef CONFIG_NO_HZ_COMMON
sections landing next to each other.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Avoid calling update_blocked_averages() when it does not in fact have
any by re-using/extending update_nohz_stats().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instead of using the cfs_rq_is_decayed() which monitors all *_avg
and *_sum, we create a cfs_rq_has_blocked() which only takes care of
util_avg and load_avg. We are only interested by these 2 values which are
decaying faster than the *_sum so we can stop the periodic update earlier.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: brendan.jackman@arm.com
Cc: dietmar.eggemann@arm.com
Cc: morten.rasmussen@foss.arm.com
Cc: valentin.schneider@arm.com
Link: http://lkml.kernel.org/r/1518517879-2280-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Stopped the periodic update of blocked load when all idle CPUs have fully
decayed. We introduce a new nohz.has_blocked that reflect if some idle
CPUs has blocked load that have to be periodiccally updated. nohz.has_blocked
is set everytime that a Idle CPU can have blocked load and it is then clear
when no more blocked load has been detected during an update. We don't need
atomic operation but only to make cure of the right ordering when updating
nohz.idle_cpus_mask and nohz.has_blocked.
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: brendan.jackman@arm.com
Cc: dietmar.eggemann@arm.com
Cc: morten.rasmussen@foss.arm.com
Cc: valentin.schneider@arm.com
Link: http://lkml.kernel.org/r/1518517879-2280-2-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It was suggested that a migration hint might be usefull for the
CPU-freq governors.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The primary observation is that nohz enter/exit is always from the
current CPU, therefore NOHZ_TICK_STOPPED does not in fact need to be
an atomic.
Secondary is that we appear to have 2 nearly identical hooks in the
nohz enter code, set_cpu_sd_state_idle() and
nohz_balance_enter_idle(). Fold the whole set_cpu_sd_state thing into
nohz_balance_{enter,exit}_idle.
Removes an atomic op from both enter and exit paths.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since we already iterate CPUs looking for work on NEWIDLE, use this
iteration to age the blocked load. If the domain for which this is
done completely spand the idle set, we can push the ILB based aging
forward.
Suggested-by: Brendan Jackman <brendan.jackman@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Teach the idle balancer about the need to update statistics which have
a different periodicity from regular balancing.
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The current:
if (nohz_kick_needed())
nohz_balancer_kick()
is pointless complexity, fold them into a single call and avoid the
various conditions at the call site.
When we introduce multiple different needs to kick the ilb, the above
construct also becomes a problem.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Split the NOHZ idle balancer into doing two separate actions:
- update blocked load statistic
- actually load-balance
Since the latter requires the former, ensure this happens. For now
always tag both bits at the same time.
Prepares for a future where we can toggle only the STATS bit.
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Using atomic_t allows us to use the more flexible bitops provided
there. Also its smaller.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instead of trying to duplicate scheduler state to track if an RT task
is running, directly use the scheduler runqueue state for it.
This vastly simplifies things and fixes a number of bugs related to
sugov and the scheduler getting out of sync wrt this state.
As a consequence we not also update the remove cfs/dl state when
iterating the shared mask.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Due to using GCC defines for configuration, some labels might be unused in
certain configurations. While adding a __maybe_unused to the label is
fine in general, the line has to be terminated with ';'. This is also
reflected in the GCC documentation, but GCC parsed the previous variant
without an error message.
This has been spotted while compiling with goto-cc, the compiler for the
CPROVER tool suite.
Signed-off-by: Norbert Manthey <nmanthey@amazon.de>
Signed-off-by: Michael Tautschnig <tautschn@amazon.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1519717660-16157-1-git-send-email-nmanthey@amazon.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Make it easier to concatenate all the scheduler .c files for single-module
compilation.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge these two small .c modules as they implement two aspects
of idle task handling.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Do the following cleanups and simplifications:
- sched/sched.h already includes <asm/paravirt.h>, so no need to
include it in sched/core.c again.
- order the <linux/sched/*.h> headers alphabetically
- add all <linux/sched/*.h> headers to kernel/sched/sched.h
- remove all unnecessary includes from the .c files that
are already included in kernel/sched/sched.h.
Finally, make all scheduler .c files use a single common header:
#include "sched.h"
... which now contains a union of the relied upon headers.
This makes the various .c files easier to read and easier to handle.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:
- fix speling in comments,
- use curly braces for multi-line statements,
- remove unnecessary parentheses from integer literals,
- capitalize consistently,
- remove stray newlines,
- add comments where necessary,
- remove invalid/unnecessary comments,
- align structure definitions and other data types vertically,
- add missing newlines for increased readability,
- fix vertical tabulation where it's misaligned,
- harmonize preprocessor conditional block labeling
and vertical alignment,
- remove line-breaks where they uglify the code,
- add newline after local variable definitions,
No change in functionality:
md5:
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm
1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
- Fixed style error: Missing space before the open parenthesis
- Fixed style warnings: 2x Missing blank line after declaration
One warning left: else after return
(I don't feel comfortable fixing that without side effects)
Signed-off-by: Mario Leinweber <marioleinweber@web.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20180302182007.28691-1-marioleinweber@web.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that the 1Hz tick is offloaded to workqueues, we can safely remove
the residual code that used to handle it locally.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1519186649-3242-7-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a CPU runs in full dynticks mode, a 1Hz tick remains in order to
keep the scheduler stats alive. However this residual tick is a burden
for bare metal tasks that can't stand any interruption at all, or want
to minimize them.
The usual boot parameters "nohz_full=" or "isolcpus=nohz" will now
outsource these scheduler ticks to the global workqueue so that a
housekeeping CPU handles those remotely. The sched_class::task_tick()
implementations have been audited and look safe to be called remotely
as the target runqueue and its current task are passed in parameter
and don't seem to be accessed locally.
Note that in the case of using isolcpus, it's still up to the user to
affine the global workqueues to the housekeeping CPUs through
/sys/devices/virtual/workqueue/cpumask or domains isolation
"isolcpus=nohz,domain".
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1519186649-3242-6-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As we prepare for offloading the residual 1hz scheduler ticks to
workqueue, let's affine those to housekeepers so that they don't
interrupt the CPUs that don't want to be disturbed.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1519186649-3242-5-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Do that rename in order to normalize the hrtick namespace.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1519186649-3242-2-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If wake_affine() pulls a task to another node for any reason and the node is
no longer preferred then temporarily stop automatic NUMA balancing pulling
the task back. Otherwise, tasks with a strong waker/wakee relationship
may constantly fight automatic NUMA balancing over where a task should
be placed.
Once again netperf is interesting here. The performance barely changes
but automatic NUMA balancing is interesting:
Hmean send-64 354.67 ( 0.00%) 352.15 ( -0.71%)
Hmean send-128 702.91 ( 0.00%) 693.84 ( -1.29%)
Hmean send-256 1350.07 ( 0.00%) 1344.19 ( -0.44%)
Hmean send-1024 5124.38 ( 0.00%) 4941.24 ( -3.57%)
Hmean send-2048 9687.44 ( 0.00%) 9624.45 ( -0.65%)
Hmean send-3312 14577.64 ( 0.00%) 14514.35 ( -0.43%)
Hmean send-4096 16393.62 ( 0.00%) 16488.30 ( 0.58%)
Hmean send-8192 26877.26 ( 0.00%) 26431.63 ( -1.66%)
Hmean send-16384 38683.43 ( 0.00%) 38264.91 ( -1.08%)
Hmean recv-64 354.67 ( 0.00%) 352.15 ( -0.71%)
Hmean recv-128 702.91 ( 0.00%) 693.84 ( -1.29%)
Hmean recv-256 1350.07 ( 0.00%) 1344.19 ( -0.44%)
Hmean recv-1024 5124.38 ( 0.00%) 4941.24 ( -3.57%)
Hmean recv-2048 9687.43 ( 0.00%) 9624.45 ( -0.65%)
Hmean recv-3312 14577.59 ( 0.00%) 14514.35 ( -0.43%)
Hmean recv-4096 16393.55 ( 0.00%) 16488.20 ( 0.58%)
Hmean recv-8192 26876.96 ( 0.00%) 26431.29 ( -1.66%)
Hmean recv-16384 38682.41 ( 0.00%) 38263.94 ( -1.08%)
NUMA alloc hit 1465986 1423090
NUMA alloc miss 0 0
NUMA interleave hit 0 0
NUMA alloc local 1465897 1423003
NUMA base PTE updates 1473 1420
NUMA huge PMD updates 0 0
NUMA page range updates 1473 1420
NUMA hint faults 1383 1312
NUMA hint local faults 451 124
NUMA hint local percent 32 9
There is a slight degrading in performance but there are slightly fewer
NUMA faults. There is a large drop in the percentage of local faults but
the bulk of migrations for netperf are in small shared libraries so it's
reflecting the fact that automatic NUMA balancing has backed off. This is
a case where despite wake_affine() and automatic NUMA balancing fighting
for placement that there is a marginal benefit to rescheduling to local
data quickly. However, it should be noted that wake_affine() and automatic
NUMA balancing fighting each other constantly is undesirable.
However, the benefit in other cases is large. This is the result for NAS
with the D class sizing on a 4-socket machine:
nas-mpi
4.15.0 4.15.0
sdnuma-v1r23 delayretry-v1r23
Time cg.D 557.00 ( 0.00%) 431.82 ( 22.47%)
Time ep.D 77.83 ( 0.00%) 79.01 ( -1.52%)
Time is.D 26.46 ( 0.00%) 26.64 ( -0.68%)
Time lu.D 727.14 ( 0.00%) 597.94 ( 17.77%)
Time mg.D 191.35 ( 0.00%) 146.85 ( 23.26%)
4.15.0 4.15.0
sdnuma-v1r23delayretry-v1r23
User 75665.20 70413.30
System 20321.59 8861.67
Elapsed 766.13 634.92
Minor Faults 16528502 7127941
Major Faults 4553 5068
NUMA alloc local 6963197 6749135
NUMA base PTE updates 366409093 107491434
NUMA huge PMD updates 687556 198880
NUMA page range updates 718437765 209317994
NUMA hint faults 13643410 4601187
NUMA hint local faults 9212593 3063996
NUMA hint local percent 67 66
Note the massive reduction in system CPU usage even though the percentage
of local faults is barely affected. There is a massive reduction in the
number of PTE updates showing that automatic NUMA balancing has backed off.
A critical observation is also that there is a massive reduction in minor
faults which is due to far fewer NUMA hinting faults being trapped.
There were questions on NAS OMP and how it behaved related to threads
being bound to CPUs. First, there are more gains than losses with this
patch applied and a reduction in system CPU usage:
nas-omp
4.16.0-rc1 4.16.0-rc1
sdnuma-v2r1 delayretry-v2r1
Time bt.D 436.71 ( 0.00%) 430.05 ( 1.53%)
Time cg.D 201.02 ( 0.00%) 180.87 ( 10.02%)
Time ep.D 32.84 ( 0.00%) 32.68 ( 0.49%)
Time is.D 9.63 ( 0.00%) 9.64 ( -0.10%)
Time lu.D 331.20 ( 0.00%) 304.80 ( 7.97%)
Time mg.D 54.87 ( 0.00%) 52.72 ( 3.92%)
Time sp.D 1108.78 ( 0.00%) 917.10 ( 17.29%)
Time ua.D 378.81 ( 0.00%) 398.83 ( -5.28%)
4.16.0-rc1 4.16.0-rc1
sdnuma-v2r1delayretry-v2r1
User 305633.08 296751.91
System 451.75 357.80
Elapsed 2595.73 2368.13
However, it does not close the gap between binding and being unbound. There
is negligible difference between the performance of the baseline and a
patched kernel when threads are bound so it is not presented here:
4.16.0-rc1 4.16.0-rc1
delayretry-bind delayretry-unbound
Time bt.D 385.02 ( 0.00%) 430.05 ( -11.70%)
Time cg.D 144.02 ( 0.00%) 180.87 ( -25.59%)
Time ep.D 32.85 ( 0.00%) 32.68 ( 0.52%)
Time is.D 10.52 ( 0.00%) 9.64 ( 8.37%)
Time lu.D 285.31 ( 0.00%) 304.80 ( -6.83%)
Time mg.D 43.21 ( 0.00%) 52.72 ( -22.01%)
Time sp.D 820.24 ( 0.00%) 917.10 ( -11.81%)
Time ua.D 337.09 ( 0.00%) 398.83 ( -18.32%)
4.16.0-rc1 4.16.0-rc1
delayretry-binddelayretry-unbound
User 277731.25 296751.91
System 261.29 357.80
Elapsed 2100.55 2368.13
Unfortunately, while performance is improved by the patch, there is still
quite a long way to go before it's equivalent to hard binding.
Other workloads like hackbench, tbench, dbench and schbench are barely
affected. dbench shows a mix of gains and losses depending on the machine
although in general, the results are more stable.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Giovanni Gherdovich <ggherdovich@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180213133730.24064-7-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
find_idlest_group() compares a local group with each other group to select
the one that is most idle. When comparing groups in different NUMA domains,
a very slight imbalance is enough to select a remote NUMA node even if the
runnable load on both groups is 0 or close to 0. This ignores the cost of
remote accesses entirely and is a problem when selecting the CPU for a
newly forked task to run on. This is problematic when a forking server
is almost guaranteed to run on a remote node incurring numerous remote
accesses and potentially causing automatic NUMA balancing to try migrate
the task back or migrate the data to another node. Similar weirdness is
observed if a basic shell command pipes output to another as each process
in the pipeline is likely to start on different nodes and then get adjusted
later by wake_affine().
This patch adds imbalance to remote domains when considering whether to
select CPUs from remote domains. If the local domain is selected, imbalance
will still be used to try select a CPU from a lower scheduler domain's group
instead of stacking tasks on the same CPU.
A variety of workloads and machines were tested and as expected, there is no
difference on UMA. The difference on NUMA can be dramatic. This is a comparison
of elapsed times running the git regression test suite. It's fork-intensive with
short-lived processes:
4.15.0 4.15.0
noexit-v1r23 sdnuma-v1r23
Elapsed min 1706.06 ( 0.00%) 1435.94 ( 15.83%)
Elapsed mean 1709.53 ( 0.00%) 1436.98 ( 15.94%)
Elapsed stddev 2.16 ( 0.00%) 1.01 ( 53.38%)
Elapsed coeffvar 0.13 ( 0.00%) 0.07 ( 44.54%)
Elapsed max 1711.59 ( 0.00%) 1438.01 ( 15.98%)
4.15.0 4.15.0
noexit-v1r23 sdnuma-v1r23
User 5434.12 5188.41
System 4878.77 3467.09
Elapsed 10259.06 8624.21
That shows a considerable reduction in elapsed times. It's important to
note that automatic NUMA balancing does not affect this load as processes
are too short-lived.
There is also a noticable impact on hackbench such as this example using
processes and pipes:
hackbench-process-pipes
4.15.0 4.15.0
noexit-v1r23 sdnuma-v1r23
Amean 1 1.0973 ( 0.00%) 0.9393 ( 14.40%)
Amean 4 1.3427 ( 0.00%) 1.3730 ( -2.26%)
Amean 7 1.4233 ( 0.00%) 1.6670 ( -17.12%)
Amean 12 3.0250 ( 0.00%) 3.3013 ( -9.13%)
Amean 21 9.0860 ( 0.00%) 9.5343 ( -4.93%)
Amean 30 14.6547 ( 0.00%) 13.2433 ( 9.63%)
Amean 48 22.5447 ( 0.00%) 20.4303 ( 9.38%)
Amean 79 29.2010 ( 0.00%) 26.7853 ( 8.27%)
Amean 110 36.7443 ( 0.00%) 35.8453 ( 2.45%)
Amean 141 45.8533 ( 0.00%) 42.6223 ( 7.05%)
Amean 172 55.1317 ( 0.00%) 50.6473 ( 8.13%)
Amean 203 64.4420 ( 0.00%) 58.3957 ( 9.38%)
Amean 234 73.2293 ( 0.00%) 67.1047 ( 8.36%)
Amean 265 80.5220 ( 0.00%) 75.7330 ( 5.95%)
Amean 296 88.7567 ( 0.00%) 82.1533 ( 7.44%)
It's not a universal win as there are occasions when spreading wide and
quickly is a benefit but it's more of a win than it is a loss. For other
workloads, there is little difference but netperf is interesting. Without
the patch, the server and client starts on different nodes but quickly get
migrated due to wake_affine. Hence, the difference is overall performance
is marginal but detectable:
4.15.0 4.15.0
noexit-v1r23 sdnuma-v1r23
Hmean send-64 349.09 ( 0.00%) 354.67 ( 1.60%)
Hmean send-128 699.16 ( 0.00%) 702.91 ( 0.54%)
Hmean send-256 1316.34 ( 0.00%) 1350.07 ( 2.56%)
Hmean send-1024 5063.99 ( 0.00%) 5124.38 ( 1.19%)
Hmean send-2048 9705.19 ( 0.00%) 9687.44 ( -0.18%)
Hmean send-3312 14359.48 ( 0.00%) 14577.64 ( 1.52%)
Hmean send-4096 16324.20 ( 0.00%) 16393.62 ( 0.43%)
Hmean send-8192 26112.61 ( 0.00%) 26877.26 ( 2.93%)
Hmean send-16384 37208.44 ( 0.00%) 38683.43 ( 3.96%)
Hmean recv-64 349.09 ( 0.00%) 354.67 ( 1.60%)
Hmean recv-128 699.16 ( 0.00%) 702.91 ( 0.54%)
Hmean recv-256 1316.34 ( 0.00%) 1350.07 ( 2.56%)
Hmean recv-1024 5063.99 ( 0.00%) 5124.38 ( 1.19%)
Hmean recv-2048 9705.16 ( 0.00%) 9687.43 ( -0.18%)
Hmean recv-3312 14359.42 ( 0.00%) 14577.59 ( 1.52%)
Hmean recv-4096 16323.98 ( 0.00%) 16393.55 ( 0.43%)
Hmean recv-8192 26111.85 ( 0.00%) 26876.96 ( 2.93%)
Hmean recv-16384 37206.99 ( 0.00%) 38682.41 ( 3.97%)
However, what is very interesting is how automatic NUMA balancing behaves.
Each netperf instance runs long enough for balancing to activate:
NUMA base PTE updates 4620 1473
NUMA huge PMD updates 0 0
NUMA page range updates 4620 1473
NUMA hint faults 4301 1383
NUMA hint local faults 1309 451
NUMA hint local percent 30 32
NUMA pages migrated 1335 491
AutoNUMA cost 21% 6%
There is an unfortunate number of remote faults although tracing indicated
that the vast majority are in shared libraries. However, the tendency to
start tasks on the same node if there is capacity means that there were
far fewer PTE updates and faults incurred overall.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Giovanni Gherdovich <ggherdovich@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180213133730.24064-6-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a task exits, it notifies the parent that it has exited. This is a
sync wakeup and the exiting task may pull the parent towards the wakers
CPU. For simple workloads like using a shell, it was observed that the
shell is pulled across nodes by exiting processes. This is daft as the
parent may be long-lived and properly placed. This patch special cases a
sync wakeup on exit to avoid pulling tasks across nodes. Testing on a range
of workloads and machines showed very little differences in performance
although there was a small 3% boost on some machines running a shellscript
intensive workload (git regression test suite).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Giovanni Gherdovich <ggherdovich@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180213133730.24064-5-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
wake_affine_weight() will consider migrating a task to, or near, the current
CPU if there is a load imbalance. If the CPUs share LLC then either CPU
is valid as a search-for-idle-sibling target and equally appropriate for
stacking two tasks on one CPU if an idle sibling is unavailable. If they do
not share cache then a cross-node migration potentially impacts locality
so while they are equal from a CPU capacity point of view, they are not
equal in terms of memory locality. In either case, it's more appropriate
to migrate only if there is a difference in their effective load.
This patch modifies wake_affine_weight() to only consider migrating a task
if there is a load imbalance for normal wakeups but will allow potential
stacking if the loads are equal and it's a sync wakeup.
For the most part, the different in performance is marginal. For example,
on a 4-socket server running netperf UDP_STREAM on localhost the differences
are as follows:
4.15.0 4.15.0
16rc0 noequal-v1r23
Hmean send-64 355.47 ( 0.00%) 349.50 ( -1.68%)
Hmean send-128 697.98 ( 0.00%) 693.35 ( -0.66%)
Hmean send-256 1328.02 ( 0.00%) 1318.77 ( -0.70%)
Hmean send-1024 5051.83 ( 0.00%) 5051.11 ( -0.01%)
Hmean send-2048 9637.02 ( 0.00%) 9601.34 ( -0.37%)
Hmean send-3312 14355.37 ( 0.00%) 14414.51 ( 0.41%)
Hmean send-4096 16464.97 ( 0.00%) 16301.37 ( -0.99%)
Hmean send-8192 26722.42 ( 0.00%) 26428.95 ( -1.10%)
Hmean send-16384 38137.81 ( 0.00%) 38046.11 ( -0.24%)
Hmean recv-64 355.47 ( 0.00%) 349.50 ( -1.68%)
Hmean recv-128 697.98 ( 0.00%) 693.35 ( -0.66%)
Hmean recv-256 1328.02 ( 0.00%) 1318.77 ( -0.70%)
Hmean recv-1024 5051.83 ( 0.00%) 5051.11 ( -0.01%)
Hmean recv-2048 9636.95 ( 0.00%) 9601.30 ( -0.37%)
Hmean recv-3312 14355.32 ( 0.00%) 14414.48 ( 0.41%)
Hmean recv-4096 16464.74 ( 0.00%) 16301.16 ( -0.99%)
Hmean recv-8192 26721.63 ( 0.00%) 26428.17 ( -1.10%)
Hmean recv-16384 38136.00 ( 0.00%) 38044.88 ( -0.24%)
Stddev send-64 7.30 ( 0.00%) 4.75 ( 34.96%)
Stddev send-128 15.15 ( 0.00%) 22.38 ( -47.66%)
Stddev send-256 13.99 ( 0.00%) 19.14 ( -36.81%)
Stddev send-1024 105.73 ( 0.00%) 67.38 ( 36.27%)
Stddev send-2048 294.57 ( 0.00%) 223.88 ( 24.00%)
Stddev send-3312 302.28 ( 0.00%) 271.74 ( 10.10%)
Stddev send-4096 195.92 ( 0.00%) 121.10 ( 38.19%)
Stddev send-8192 399.71 ( 0.00%) 563.77 ( -41.04%)
Stddev send-16384 1163.47 ( 0.00%) 1103.68 ( 5.14%)
Stddev recv-64 7.30 ( 0.00%) 4.75 ( 34.96%)
Stddev recv-128 15.15 ( 0.00%) 22.38 ( -47.66%)
Stddev recv-256 13.99 ( 0.00%) 19.14 ( -36.81%)
Stddev recv-1024 105.73 ( 0.00%) 67.38 ( 36.27%)
Stddev recv-2048 294.59 ( 0.00%) 223.89 ( 24.00%)
Stddev recv-3312 302.24 ( 0.00%) 271.75 ( 10.09%)
Stddev recv-4096 196.03 ( 0.00%) 121.14 ( 38.20%)
Stddev recv-8192 399.86 ( 0.00%) 563.65 ( -40.96%)
Stddev recv-16384 1163.79 ( 0.00%) 1103.86 ( 5.15%)
The difference in overall performance is marginal but note that most
measurements are less variable. There were similar observations for other
netperf comparisons. hackbench with sockets or threads with processes or
threads showed minor difference with some reduction of migration. tbench
showed only marginal differences that were within the noise. dbench,
regardless of filesystem, showed minor differences all of which are
within noise. Multiple machines, both UMA and NUMA were tested without
any regressions showing up.
The biggest risk with a patch like this is affecting wakeup latencies.
However, the schbench load from Facebook which is very sensitive to wakeup
latency showed a mixed result with mostly improvements in wakeup latency:
4.15.0 4.15.0
16rc0 noequal-v1r23
Lat 50.00th-qrtle-1 38.00 ( 0.00%) 38.00 ( 0.00%)
Lat 75.00th-qrtle-1 49.00 ( 0.00%) 41.00 ( 16.33%)
Lat 90.00th-qrtle-1 52.00 ( 0.00%) 50.00 ( 3.85%)
Lat 95.00th-qrtle-1 54.00 ( 0.00%) 51.00 ( 5.56%)
Lat 99.00th-qrtle-1 63.00 ( 0.00%) 60.00 ( 4.76%)
Lat 99.50th-qrtle-1 66.00 ( 0.00%) 61.00 ( 7.58%)
Lat 99.90th-qrtle-1 78.00 ( 0.00%) 65.00 ( 16.67%)
Lat 50.00th-qrtle-2 38.00 ( 0.00%) 38.00 ( 0.00%)
Lat 75.00th-qrtle-2 42.00 ( 0.00%) 43.00 ( -2.38%)
Lat 90.00th-qrtle-2 46.00 ( 0.00%) 48.00 ( -4.35%)
Lat 95.00th-qrtle-2 49.00 ( 0.00%) 50.00 ( -2.04%)
Lat 99.00th-qrtle-2 55.00 ( 0.00%) 57.00 ( -3.64%)
Lat 99.50th-qrtle-2 58.00 ( 0.00%) 60.00 ( -3.45%)
Lat 99.90th-qrtle-2 65.00 ( 0.00%) 68.00 ( -4.62%)
Lat 50.00th-qrtle-4 41.00 ( 0.00%) 41.00 ( 0.00%)
Lat 75.00th-qrtle-4 45.00 ( 0.00%) 46.00 ( -2.22%)
Lat 90.00th-qrtle-4 50.00 ( 0.00%) 50.00 ( 0.00%)
Lat 95.00th-qrtle-4 54.00 ( 0.00%) 53.00 ( 1.85%)
Lat 99.00th-qrtle-4 61.00 ( 0.00%) 61.00 ( 0.00%)
Lat 99.50th-qrtle-4 65.00 ( 0.00%) 64.00 ( 1.54%)
Lat 99.90th-qrtle-4 76.00 ( 0.00%) 82.00 ( -7.89%)
Lat 50.00th-qrtle-8 48.00 ( 0.00%) 46.00 ( 4.17%)
Lat 75.00th-qrtle-8 55.00 ( 0.00%) 54.00 ( 1.82%)
Lat 90.00th-qrtle-8 60.00 ( 0.00%) 59.00 ( 1.67%)
Lat 95.00th-qrtle-8 63.00 ( 0.00%) 63.00 ( 0.00%)
Lat 99.00th-qrtle-8 71.00 ( 0.00%) 69.00 ( 2.82%)
Lat 99.50th-qrtle-8 74.00 ( 0.00%) 73.00 ( 1.35%)
Lat 99.90th-qrtle-8 98.00 ( 0.00%) 90.00 ( 8.16%)
Lat 50.00th-qrtle-16 56.00 ( 0.00%) 55.00 ( 1.79%)
Lat 75.00th-qrtle-16 68.00 ( 0.00%) 67.00 ( 1.47%)
Lat 90.00th-qrtle-16 77.00 ( 0.00%) 78.00 ( -1.30%)
Lat 95.00th-qrtle-16 82.00 ( 0.00%) 84.00 ( -2.44%)
Lat 99.00th-qrtle-16 90.00 ( 0.00%) 93.00 ( -3.33%)
Lat 99.50th-qrtle-16 93.00 ( 0.00%) 97.00 ( -4.30%)
Lat 99.90th-qrtle-16 110.00 ( 0.00%) 110.00 ( 0.00%)
Lat 50.00th-qrtle-32 68.00 ( 0.00%) 62.00 ( 8.82%)
Lat 75.00th-qrtle-32 90.00 ( 0.00%) 83.00 ( 7.78%)
Lat 90.00th-qrtle-32 110.00 ( 0.00%) 100.00 ( 9.09%)
Lat 95.00th-qrtle-32 122.00 ( 0.00%) 111.00 ( 9.02%)
Lat 99.00th-qrtle-32 145.00 ( 0.00%) 133.00 ( 8.28%)
Lat 99.50th-qrtle-32 154.00 ( 0.00%) 143.00 ( 7.14%)
Lat 99.90th-qrtle-32 2316.00 ( 0.00%) 515.00 ( 77.76%)
Lat 50.00th-qrtle-35 69.00 ( 0.00%) 72.00 ( -4.35%)
Lat 75.00th-qrtle-35 92.00 ( 0.00%) 95.00 ( -3.26%)
Lat 90.00th-qrtle-35 111.00 ( 0.00%) 114.00 ( -2.70%)
Lat 95.00th-qrtle-35 122.00 ( 0.00%) 124.00 ( -1.64%)
Lat 99.00th-qrtle-35 142.00 ( 0.00%) 144.00 ( -1.41%)
Lat 99.50th-qrtle-35 150.00 ( 0.00%) 154.00 ( -2.67%)
Lat 99.90th-qrtle-35 6104.00 ( 0.00%) 5640.00 ( 7.60%)
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Giovanni Gherdovich <ggherdovich@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180213133730.24064-4-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On sync wakeups, the previous CPU effective load may not be used so delay
the calculation until it's needed.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Giovanni Gherdovich <ggherdovich@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180213133730.24064-3-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The only caller of wake_affine() knows the CPU ID. Pass it in instead of
rechecking it.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Giovanni Gherdovich <ggherdovich@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180213133730.24064-2-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since schedutil kernel thread directly set priority to 0, the macro
SUGOV_KTHREAD_PRIORITY is not used. So remove it.
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vikram Mulukutla <markivx@codeaurora.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/1518097702-9665-1-git-send-email-leo.yan@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Mark noticed that he had sporadic "spinlock recursion" warnings from
the DEBUG_SPINLOCK code. Now rq->lock is special in that the owner
changes in the middle of a context switch.
It so happens that we fix up the lock.owner too late, @prev can run
(remotely) the moment prev->on_cpu is cleared, this then allows @prev
to again try and acquire this rq->lock and trigger this warning.
So we have to switch lock.owner before clearing prev->on_cpu.
Do this by moving the DEBUG_SPINLOCK annotation from after switch_to()
to before switch_to() and collect all lockdep annotations there into
prepare_lock_switch() to mirror the existing finish_lock_switch().
Debugged-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
rq->clock_task may be updated between the two calls of
rq_clock_task() in update_curr_rt(). Calling rq_clock_task() only
once makes it more accurate and efficient, taking update_curr() as
reference.
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: zhong.weidong@zte.com.cn
Link: http://lkml.kernel.org/r/1517882008-44552-1-git-send-email-wen.yang99@zte.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
rq->clock_task may be updated between the two calls of
rq_clock_task() in update_curr_dl(). Calling rq_clock_task() only
once makes it more accurate and efficient, taking update_curr() as
reference.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: zhong.weidong@zte.com.cn
Link: http://lkml.kernel.org/r/1517882148-44599-1-git-send-email-wen.yang99@zte.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Remove a useless space in # ifdef and align it with others.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1518512382-29426-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While adding cgroup2 interface for the cpu controller, 0d5936344f
("sched: Implement interface for cgroup unified hierarchy") forgot to
update input validation and left it to reject cpu.max config if any
descendant has set a higher value.
cgroup2 officially supports delegation and a descendant must not be
able to restrict what its ancestors can configure. For absolute
limits such as cpu.max and memory.max, this means that the config at
each level should only act as the upper limit at that level and
shouldn't interfere with what other cgroups can configure.
This patch updates config validation on cgroup2 so that the cpu
controller follows the same convention.
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 0d5936344f ("sched: Implement interface for cgroup unified hierarchy")
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org # v4.15+
The select_idle_sibling() (SIS) rewrite in commit:
10e2f1acd0 ("sched/core: Rewrite and improve select_idle_siblings()")
... replaced a domain iteration with a search that broadly speaking
does a wrapped walk of the scheduler domain sharing a last-level-cache.
While this had a number of improvements, one consequence is that two tasks
that share a waker/wakee relationship push each other around a socket. Even
though two tasks may be active, all cores are evenly used. This is great from
a search perspective and spreads a load across individual cores, but it has
adverse consequences for cpufreq. As each CPU has relatively low utilisation,
cpufreq may decide the utilisation is too low to used a higher P-state and
overall computation throughput suffers.
While individual cpufreq and cpuidle drivers may compensate by artifically
boosting P-state (at c0) or avoiding lower C-states (during idle), it does
not help if hardware-based cpufreq (e.g. HWP) is used.
This patch tracks a recently used CPU based on what CPU a task was running
on when it last was a waker a CPU it was recently using when a task is a
wakee. During SIS, the recently used CPU is used as a target if it's still
allowed by the task and is idle.
The benefit may be non-obvious so consider an example of two tasks
communicating back and forth. Task A may be an application doing IO where
task B is a kworker or kthread like journald. Task A may issue IO, wake
B and B wakes up A on completion. With the existing scheme this may look
like the following (potentially different IDs if SMT is in use but similar
principal applies).
A (cpu 0) wake B (wakes on cpu 1)
B (cpu 1) wake A (wakes on cpu 2)
A (cpu 2) wake B (wakes on cpu 3)
etc.
A careful reader may wonder why CPU 0 was not idle when B wakes A the
first time and it's simply due to the fact that A can be rescheduled to
another CPU and the pattern is that prev == target when B tries to wakeup A
and the information about CPU 0 has been lost.
With this patch, the pattern is more likely to be:
A (cpu 0) wake B (wakes on cpu 1)
B (cpu 1) wake A (wakes on cpu 0)
A (cpu 0) wake B (wakes on cpu 1)
etc
i.e. two communicating casts are more likely to use just two cores instead
of all available cores sharing a LLC.
The most dramatic speedup was noticed on dbench using the XFS filesystem on
UMA as clients interact heavily with workqueues in that configuration. Note
that a similar speedup is not observed on ext4 as the wakeup pattern
is different:
4.15.0-rc9 4.15.0-rc9
waprev-v1 biasancestor-v1
Hmean 1 287.54 ( 0.00%) 817.01 ( 184.14%)
Hmean 2 1268.12 ( 0.00%) 1781.24 ( 40.46%)
Hmean 4 1739.68 ( 0.00%) 1594.47 ( -8.35%)
Hmean 8 2464.12 ( 0.00%) 2479.56 ( 0.63%)
Hmean 64 1455.57 ( 0.00%) 1434.68 ( -1.44%)
The results can be less dramatic on NUMA where automatic balancing interferes
with the test. It's also known that network benchmarks running on localhost
also benefit quite a bit from this patch (roughly 10% on netperf RR for UDP
and TCP depending on the machine). Hackbench also seens small improvements
(6-11% depending on machine and thread count). The facebook schbench was also
tested but in most cases showed little or no different to wakeup latencies.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180130104555.4125-5-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
wake_affine_idle() prefers to move a task to the current CPU if the
wakeup is due to an interrupt. The expectation is that the interrupt
data is cache hot and relevant to the waking task as well as avoiding
a search. However, there is no way to determine if there was cache hot
data on the previous CPU that may exceed the interrupt data. Furthermore,
round-robin delivery of interrupts can migrate tasks around a socket where
each CPU is under-utilised. This can interact badly with cpufreq which
makes decisions based on per-cpu data. It has been observed on machines
with HWP that p-states are not boosted to their maximum levels even though
the workload is latency and throughput sensitive.
This patch uses the previous CPU for the task if it's idle and cache-affine
with the current CPU even if the current CPU is idle due to the wakup
being related to the interrupt. This reduces migrations at the cost of
the interrupt data not being cache hot when the task wakes.
A variety of workloads were tested on various machines and no adverse
impact was noticed that was outside noise. dbench on ext4 on UMA showed
roughly 10% reduction in the number of CPU migrations and it is a case
where interrupts are frequent for IO competions. In most cases, the
difference in performance is quite small but variability is often
reduced. For example, this is the result for pgbench running on a UMA
machine with different numbers of clients.
4.15.0-rc9 4.15.0-rc9
baseline waprev-v1
Hmean 1 22096.28 ( 0.00%) 22734.86 ( 2.89%)
Hmean 4 74633.42 ( 0.00%) 75496.77 ( 1.16%)
Hmean 7 115017.50 ( 0.00%) 113030.81 ( -1.73%)
Hmean 12 126209.63 ( 0.00%) 126613.40 ( 0.32%)
Hmean 16 131886.91 ( 0.00%) 130844.35 ( -0.79%)
Stddev 1 636.38 ( 0.00%) 417.11 ( 34.46%)
Stddev 4 614.64 ( 0.00%) 583.24 ( 5.11%)
Stddev 7 542.46 ( 0.00%) 435.45 ( 19.73%)
Stddev 12 173.93 ( 0.00%) 171.50 ( 1.40%)
Stddev 16 671.42 ( 0.00%) 680.30 ( -1.32%)
CoeffVar 1 2.88 ( 0.00%) 1.83 ( 36.26%)
Note that the different in performance is marginal but for low utilisation,
there is less variability.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180130104555.4125-4-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is a preparation patch that has wake_affine*() return a CPU ID instead of
a boolean. The intent is to allow the wake_affine() helpers to be avoided
if a decision is already made. This patch has no functional change.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180130104555.4125-3-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
wake_affine_idle() takes parameters it never uses so clean it up.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180130104555.4125-2-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
rq->clock_task may be updated between the two calls of
rq_clock_task() in update_curr_rt(). Calling rq_clock_task() only
once makes it more accurate and efficient, taking update_curr() as
reference.
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: zhong.weidong@zte.com.cn
Link: http://lkml.kernel.org/r/1517800721-42092-1-git-send-email-wen.yang99@zte.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When issuing an IPI RT push, where an IPI is sent to each CPU that has more
than one RT task scheduled on it, it references the root domain's rto_mask,
that contains all the CPUs within the root domain that has more than one RT
task in the runable state. The problem is, after the IPIs are initiated, the
rq->lock is released. This means that the root domain that is associated to
the run queue could be freed while the IPIs are going around.
Add a sched_get_rd() and a sched_put_rd() that will increment and decrement
the root domain's ref count respectively. This way when initiating the IPIs,
the scheduler will up the root domain's ref count before releasing the
rq->lock, ensuring that the root domain does not go away until the IPI round
is complete.
Reported-by: Pavan Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4bdced5c9a ("sched/rt: Simplify the IPI based RT balancing logic")
Link: http://lkml.kernel.org/r/CAEU1=PkiHO35Dzna8EQqNSKW1fr1y1zRQ5y66X117MG06sQtNA@mail.gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the rto_push_irq_work_func() is called, it looks at the RT overloaded
bitmask in the root domain via the runqueue (rq->rd). The problem is that
during CPU up and down, nothing here stops rq->rd from changing between
taking the rq->rd->rto_lock and releasing it. That means the lock that is
released is not the same lock that was taken.
Instead of using this_rq()->rd to get the root domain, as the irq work is
part of the root domain, we can simply get the root domain from the irq work
that is passed to the routine:
container_of(work, struct root_domain, rto_push_work)
This keeps the root domain consistent.
Reported-by: Pavan Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4bdced5c9a ("sched/rt: Simplify the IPI based RT balancing logic")
Link: http://lkml.kernel.org/r/CAEU1=PkiHO35Dzna8EQqNSKW1fr1y1zRQ5y66X117MG06sQtNA@mail.gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
These functions are already gated by schedstats_enabled(), there is no
point in then issuing another static_branch for every individual
update in them.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The whole of ttwu_stat() is guarded by a single schedstat_enabled(),
there is absolutely no point in then issuing another static_branch for
every single schedstat_inc() in there.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Provide core serializing membarrier command to support memory reclaim
by JIT.
Each architecture needs to explicitly opt into that support by
documenting in their architecture code how they provide the core
serializing instructions required when returning from the membarrier
IPI, and after the scheduler has updated the curr->mm pointer (before
going back to user-space). They should then select
ARCH_HAS_MEMBARRIER_SYNC_CORE to enable support for that command on
their architecture.
Architectures selecting this feature need to either document that
they issue core serializing instructions when returning to user-space,
or implement their architecture-specific sync_core_before_usermode().
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Andrew Hunter <ahh@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Avi Kivity <avi@scylladb.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: David Sehr <sehr@google.com>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maged Michael <maged.michael@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Link: http://lkml.kernel.org/r/20180129202020.8515-9-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Allow expedited membarrier to be used for data shared between processes
through shared memory.
Processes wishing to receive the membarriers register with
MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED. Those which want to issue
membarrier invoke MEMBARRIER_CMD_GLOBAL_EXPEDITED.
This allows extremely simple kernel-level implementation: we have almost
everything we need with the PRIVATE_EXPEDITED barrier code. All we need
to do is to add a flag in the mm_struct that will be used to check
whether we need to send the IPI to the current thread of each CPU.
There is a slight downside to this approach compared to targeting
specific shared memory users: when performing a membarrier operation,
all registered "global" receivers will get the barrier, even if they
don't share a memory mapping with the sender issuing
MEMBARRIER_CMD_GLOBAL_EXPEDITED.
This registration approach seems to fit the requirement of not
disturbing processes that really deeply care about real-time: they
simply should not register with MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED.
In order to align the membarrier command names, the "MEMBARRIER_CMD_SHARED"
command is renamed to "MEMBARRIER_CMD_GLOBAL", keeping an alias of
MEMBARRIER_CMD_SHARED to MEMBARRIER_CMD_GLOBAL for UAPI header backward
compatibility.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Andrew Hunter <ahh@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Avi Kivity <avi@scylladb.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: David Sehr <sehr@google.com>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maged Michael <maged.michael@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-api@vger.kernel.org
Link: http://lkml.kernel.org/r/20180129202020.8515-5-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Document the membarrier requirement on having a full memory barrier in
__schedule() after coming from user-space, before storing to rq->curr.
It is provided by smp_mb__after_spinlock() in __schedule().
Document that membarrier requires a full barrier on transition from
kernel thread to userspace thread. We currently have an implicit barrier
from atomic_dec_and_test() in mmdrop() that ensures this.
The x86 switch_mm_irqs_off() full barrier is currently provided by many
cpumask update operations as well as write_cr3(). Document that
write_cr3() provides this barrier.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Andrew Hunter <ahh@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Avi Kivity <avi@scylladb.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: David Sehr <sehr@google.com>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maged Michael <maged.michael@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-api@vger.kernel.org
Link: http://lkml.kernel.org/r/20180129202020.8515-4-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Allow PowerPC to skip the full memory barrier in switch_mm(), and
only issue the barrier when scheduling into a task belonging to a
process that has registered to use expedited private.
Threads targeting the same VM but which belong to different thread
groups is a tricky case. It has a few consequences:
It turns out that we cannot rely on get_nr_threads(p) to count the
number of threads using a VM. We can use
(atomic_read(&mm->mm_users) == 1 && get_nr_threads(p) == 1)
instead to skip the synchronize_sched() for cases where the VM only has
a single user, and that user only has a single thread.
It also turns out that we cannot use for_each_thread() to set
thread flags in all threads using a VM, as it only iterates on the
thread group.
Therefore, test the membarrier state variable directly rather than
relying on thread flags. This means
membarrier_register_private_expedited() needs to set the
MEMBARRIER_STATE_PRIVATE_EXPEDITED flag, issue synchronize_sched(), and
only then set MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY which allows
private expedited membarrier commands to succeed.
membarrier_arch_switch_mm() now tests for the
MEMBARRIER_STATE_PRIVATE_EXPEDITED flag.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Andrew Hunter <ahh@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Avi Kivity <avi@scylladb.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: David Sehr <sehr@google.com>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maged Michael <maged.michael@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20180129202020.8515-3-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull printk updates from Petr Mladek:
- Add a console_msg_format command line option:
The value "default" keeps the old "[time stamp] text\n" format. The
value "syslog" allows to see the syslog-like "<log
level>[timestamp] text" format.
This feature was requested by people doing regression tests, for
example, 0day robot. They want to have both filtered and full logs
at hands.
- Reduce the risk of softlockup:
Pass the console owner in a busy loop.
This is a new approach to the old problem. It was first proposed by
Steven Rostedt on Kernel Summit 2017. It marks a context in which
the console_lock owner calls console drivers and could not sleep.
On the other side, printk() callers could detect this state and use
a busy wait instead of a simple console_trylock(). Finally, the
console_lock owner checks if there is a busy waiter at the end of
the special context and eventually passes the console_lock to the
waiter.
The hand-off works surprisingly well and helps in many situations.
Well, there is still a possibility of the softlockup, for example,
when the flood of messages stops and the last owner still has too
much to flush.
There is increasing number of people having problems with
printk-related softlockups. We might eventually need to get better
solution. Anyway, this looks like a good start and promising
direction.
- Do not allow to schedule in console_unlock() called from printk():
This reverts an older controversial commit. The reschedule helped
to avoid softlockups. But it also slowed down the console output.
This patch is obsoleted by the new console waiter logic described
above. In fact, the reschedule made the hand-off less effective.
- Deprecate "%pf" and "%pF" format specifier:
It was needed on ia64, ppc64 and parisc64 to dereference function
descriptors and show the real function address. It is done
transparently by "%ps" and "pS" format specifier now.
Sergey Senozhatsky found that all the function descriptors were in
a special elf section and could be easily detected.
- Remove printk_symbol() API:
It has been obsoleted by "%pS" format specifier, and this change
helped to remove few continuous lines and a less intuitive old API.
- Remove redundant memsets:
Sergey removed unnecessary memset when processing printk.devkmsg
command line option.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk: (27 commits)
printk: drop redundant devkmsg_log_str memsets
printk: Never set console_may_schedule in console_trylock()
printk: Hide console waiter logic into helpers
printk: Add console owner and waiter logic to load balance console writes
kallsyms: remove print_symbol() function
checkpatch: add pF/pf deprecation warning
symbol lookup: introduce dereference_symbol_descriptor()
parisc64: Add .opd based function descriptor dereference
powerpc64: Add .opd based function descriptor dereference
ia64: Add .opd based function descriptor dereference
sections: split dereference_function_descriptor()
openrisc: Fix conflicting types for _exext and _stext
lib: do not use print_symbol()
irq debug: do not use print_symbol()
sysfs: do not use print_symbol()
drivers: do not use print_symbol()
x86: do not use print_symbol()
unicore32: do not use print_symbol()
sh: do not use print_symbol()
mn10300: do not use print_symbol()
...
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle were:
- Implement frequency/CPU invariance and OPP selection for
SCHED_DEADLINE (Juri Lelli)
- Tweak the task migration logic for better multi-tasking
workload scalability (Mel Gorman)
- Misc cleanups, fixes and improvements"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/deadline: Make bandwidth enforcement scale-invariant
sched/cpufreq: Move arch_scale_{freq,cpu}_capacity() outside of #ifdef CONFIG_SMP
sched/cpufreq: Remove arch_scale_freq_capacity()'s 'sd' parameter
sched/cpufreq: Always consider all CPUs when deciding next freq
sched/cpufreq: Split utilization signals
sched/cpufreq: Change the worker kthread to SCHED_DEADLINE
sched/deadline: Move CPU frequency selection triggering points
sched/cpufreq: Use the DEADLINE utilization signal
sched/deadline: Implement "runtime overrun signal" support
sched/fair: Only immediately migrate tasks due to interrupts if prev and target CPUs share cache
sched/fair: Correct obsolete comment about cpufreq_update_util()
sched/fair: Remove impossible condition from find_idlest_group_cpu()
sched/cpufreq: Don't pass flags to sugov_set_iowait_boost()
sched/cpufreq: Initialize sg_cpu->flags to 0
sched/fair: Consider RT/IRQ pressure in capacity_spare_wake()
sched/fair: Use 'unsigned long' for utilization, consistently
sched/core: Rework and clarify prepare_lock_switch()
sched/fair: Remove unused 'curr' parameter from wakeup_gran
sched/headers: Constify object_is_on_stack()
Pull RCU updates from Ingo Molnar:
"The main RCU changes in this cycle were:
- Updates to use cond_resched() instead of cond_resched_rcu_qs()
where feasible (currently everywhere except in kernel/rcu and in
kernel/torture.c). Also a couple of fixes to avoid sending IPIs to
offline CPUs.
- Updates to simplify RCU's dyntick-idle handling.
- Updates to remove almost all uses of smp_read_barrier_depends() and
read_barrier_depends().
- Torture-test updates.
- Miscellaneous fixes"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits)
torture: Save a line in stutter_wait(): while -> for
torture: Eliminate torture_runnable and perf_runnable
torture: Make stutter less vulnerable to compilers and races
locking/locktorture: Fix num reader/writer corner cases
locking/locktorture: Fix rwsem reader_delay
torture: Place all torture-test modules in one MAINTAINERS group
rcutorture/kvm-build.sh: Skip build directory check
rcutorture: Simplify functions.sh include path
rcutorture: Simplify logging
rcutorture/kvm-recheck-*: Improve result directory readability check
rcutorture/kvm.sh: Support execution from any directory
rcutorture/kvm.sh: Use consistent help text for --qemu-args
rcutorture/kvm.sh: Remove unused variable, `alldone`
rcutorture: Remove unused script, config2frag.sh
rcutorture/configinit: Fix build directory error message
rcutorture: Preempt RCU-preempt readers more vigorously
torture: Reduce #ifdefs for preempt_schedule()
rcu: Remove have_rcu_nocb_mask from tree_plugin.h
rcu: Add comment giving debug strategy for double call_rcu()
tracing, rcu: Hide trace event rcu_nocb_wake when not used
...
Before commit:
e33a9bba85 ("sched/core: move IO scheduling accounting from io_schedule_timeout() into scheduler")
delayacct_blkio_end() was called after context-switching into the task which
completed I/O.
This resulted in double counting: the task would account a delay both waiting
for I/O and for time spent in the runqueue.
With e33a9bba85, delayacct_blkio_end() is called by try_to_wake_up().
In ttwu, we have not yet context-switched. This is more correct, in that
the delay accounting ends when the I/O is complete.
But delayacct_blkio_end() relies on 'get_current()', and we have not yet
context-switched into the task whose I/O completed. This results in the
wrong task having its delay accounting statistics updated.
Instead of doing that, pass the task_struct being woken to delayacct_blkio_end(),
so that it can update the statistics of the correct task.
Signed-off-by: Josh Snyder <joshs@netflix.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Cc: <stable@vger.kernel.org>
Cc: Brendan Gregg <bgregg@netflix.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-block@vger.kernel.org
Fixes: e33a9bba85 ("sched/core: move IO scheduling accounting from io_schedule_timeout() into scheduler")
Link: http://lkml.kernel.org/r/1513613712-571-1-git-send-email-joshs@netflix.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler fixes from Ingo Molnar:
"A Kconfig fix, a build fix and a membarrier bug fix"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
membarrier: Disable preemption when calling smp_call_function_many()
sched/isolation: Make CONFIG_CPU_ISOLATION=y depend on SMP or COMPILE_TEST
ia64, sched/cputime: Fix build error if CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y
This patch adds the possibility of getting the delivery of a SIGXCPU
signal whenever there is a runtime overrun. The request is done through
the sched_flags field within the sched_attr structure.
Forward port of https://lkml.org/lkml/2009/10/16/170
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1513077024-25461-1-git-send-email-claudio@evidence.eu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If waking from an idle CPU due to an interrupt then it's possible that
the waker task will be pulled to wake on the current CPU. Unfortunately,
depending on the type of interrupt and IRQ configuration, there may not
be a strong relationship between the CPU an interrupt was delivered on
and the CPU a task was running on. For example, the interrupts could all
be delivered to CPUs on one particular node due to the machine topology
or IRQ affinity configuration. Another example is an interrupt for an IO
completion which can be delivered to any CPU where there is no guarantee
the data is either cache hot or even local.
This patch was motivated by the observation that an IO workload was
being pulled cross-node on a frequent basis when IO completed. From a
wakeup latency perspective, it's still useful to know that an idle CPU is
immediately available for use but lets only consider an automatic migration
if the CPUs share cache to limit damage due to NUMA migrations. Migrations
may still occur if wake_affine_weight determines it's appropriate.
These are the throughput results for dbench running on ext4 comparing
4.15-rc3 and this patch on a 2-socket machine where interrupts due to IO
completions can happen on any CPU.
4.15.0-rc3 4.15.0-rc3
vanilla lessmigrate
Hmean 1 854.64 ( 0.00%) 865.01 ( 1.21%)
Hmean 2 1229.60 ( 0.00%) 1274.44 ( 3.65%)
Hmean 4 1591.81 ( 0.00%) 1628.08 ( 2.28%)
Hmean 8 1845.04 ( 0.00%) 1831.80 ( -0.72%)
Hmean 16 2038.61 ( 0.00%) 2091.44 ( 2.59%)
Hmean 32 2327.19 ( 0.00%) 2430.29 ( 4.43%)
Hmean 64 2570.61 ( 0.00%) 2568.54 ( -0.08%)
Hmean 128 2481.89 ( 0.00%) 2499.28 ( 0.70%)
Stddev 1 14.31 ( 0.00%) 5.35 ( 62.65%)
Stddev 2 21.29 ( 0.00%) 11.09 ( 47.92%)
Stddev 4 7.22 ( 0.00%) 6.80 ( 5.92%)
Stddev 8 26.70 ( 0.00%) 9.41 ( 64.76%)
Stddev 16 22.40 ( 0.00%) 20.01 ( 10.70%)
Stddev 32 45.13 ( 0.00%) 44.74 ( 0.85%)
Stddev 64 93.10 ( 0.00%) 93.18 ( -0.09%)
Stddev 128 184.28 ( 0.00%) 177.85 ( 3.49%)
Note the small increase in throughput for low thread counts but also
note that the standard deviation for each sample during the test run is
lower. The throughput figures for dbench can be misleading so the benchmark
is actually modified to time the latency of the processing of one load
file with many samples taken. The difference in latency is
4.15.0-rc3 4.15.0-rc3
vanilla lessmigrate
Amean 1 21.71 ( 0.00%) 21.47 ( 1.08%)
Amean 2 30.89 ( 0.00%) 29.58 ( 4.26%)
Amean 4 47.54 ( 0.00%) 46.61 ( 1.97%)
Amean 8 82.71 ( 0.00%) 82.81 ( -0.12%)
Amean 16 149.45 ( 0.00%) 145.01 ( 2.97%)
Amean 32 265.49 ( 0.00%) 248.43 ( 6.42%)
Amean 64 463.23 ( 0.00%) 463.55 ( -0.07%)
Amean 128 933.97 ( 0.00%) 935.50 ( -0.16%)
Stddev 1 1.58 ( 0.00%) 1.54 ( 2.26%)
Stddev 2 2.84 ( 0.00%) 2.95 ( -4.15%)
Stddev 4 6.78 ( 0.00%) 6.85 ( -0.99%)
Stddev 8 16.85 ( 0.00%) 16.37 ( 2.85%)
Stddev 16 41.59 ( 0.00%) 41.04 ( 1.32%)
Stddev 32 111.05 ( 0.00%) 105.11 ( 5.35%)
Stddev 64 285.94 ( 0.00%) 288.01 ( -0.72%)
Stddev 128 803.39 ( 0.00%) 809.73 ( -0.79%)
It's a small improvement which is not surprising given that migrations that
migrate to a different node as not that common. However, it is noticeable
in the CPU migration statistics which are reduced by 24%.
There was a query for v1 of this patch about NAS so here are the results
for C-class using MPI for parallelisation on the same machine
nas-mpi
4.15.0-rc3 4.15.0-rc3
vanilla noirq
Time cg.C 24.25 ( 0.00%) 23.17 ( 4.45%)
Time ep.C 8.22 ( 0.00%) 8.29 ( -0.85%)
Time ft.C 22.67 ( 0.00%) 20.34 ( 10.28%)
Time is.C 1.42 ( 0.00%) 1.47 ( -3.52%)
Time lu.C 55.62 ( 0.00%) 54.81 ( 1.46%)
Time mg.C 7.93 ( 0.00%) 7.91 ( 0.25%)
4.15.0-rc3 4.15.0-rc3
vanilla noirq-v1r1
User 3799.96 3748.34
System 672.10 626.15
Elapsed 91.91 79.49
lu.C sees a small gain, ft.C a large gain and ep.C and is.C see small
regressions but in terms of absolute time, the difference is small and
likely within run-to-run variance. System CPU usage is slightly reduced.
schbench from Facebook was also requested. This is a bit of a mixed bag but
it's important to note that this workload should not be heavily impacted
by wakeups from interrupt context.
4.15.0-rc3 4.15.0-rc3
vanilla noirq-v1r1
Lat 50.00th-qrtle-1 41.00 ( 0.00%) 41.00 ( 0.00%)
Lat 75.00th-qrtle-1 42.00 ( 0.00%) 42.00 ( 0.00%)
Lat 90.00th-qrtle-1 43.00 ( 0.00%) 44.00 ( -2.33%)
Lat 95.00th-qrtle-1 44.00 ( 0.00%) 46.00 ( -4.55%)
Lat 99.00th-qrtle-1 57.00 ( 0.00%) 58.00 ( -1.75%)
Lat 99.50th-qrtle-1 59.00 ( 0.00%) 59.00 ( 0.00%)
Lat 99.90th-qrtle-1 67.00 ( 0.00%) 78.00 ( -16.42%)
Lat 50.00th-qrtle-2 40.00 ( 0.00%) 51.00 ( -27.50%)
Lat 75.00th-qrtle-2 45.00 ( 0.00%) 56.00 ( -24.44%)
Lat 90.00th-qrtle-2 53.00 ( 0.00%) 59.00 ( -11.32%)
Lat 95.00th-qrtle-2 57.00 ( 0.00%) 61.00 ( -7.02%)
Lat 99.00th-qrtle-2 67.00 ( 0.00%) 71.00 ( -5.97%)
Lat 99.50th-qrtle-2 69.00 ( 0.00%) 74.00 ( -7.25%)
Lat 99.90th-qrtle-2 83.00 ( 0.00%) 77.00 ( 7.23%)
Lat 50.00th-qrtle-4 51.00 ( 0.00%) 51.00 ( 0.00%)
Lat 75.00th-qrtle-4 57.00 ( 0.00%) 56.00 ( 1.75%)
Lat 90.00th-qrtle-4 60.00 ( 0.00%) 59.00 ( 1.67%)
Lat 95.00th-qrtle-4 62.00 ( 0.00%) 62.00 ( 0.00%)
Lat 99.00th-qrtle-4 73.00 ( 0.00%) 72.00 ( 1.37%)
Lat 99.50th-qrtle-4 76.00 ( 0.00%) 74.00 ( 2.63%)
Lat 99.90th-qrtle-4 85.00 ( 0.00%) 78.00 ( 8.24%)
Lat 50.00th-qrtle-8 54.00 ( 0.00%) 58.00 ( -7.41%)
Lat 75.00th-qrtle-8 59.00 ( 0.00%) 62.00 ( -5.08%)
Lat 90.00th-qrtle-8 65.00 ( 0.00%) 66.00 ( -1.54%)
Lat 95.00th-qrtle-8 67.00 ( 0.00%) 70.00 ( -4.48%)
Lat 99.00th-qrtle-8 78.00 ( 0.00%) 79.00 ( -1.28%)
Lat 99.50th-qrtle-8 81.00 ( 0.00%) 80.00 ( 1.23%)
Lat 99.90th-qrtle-8 116.00 ( 0.00%) 83.00 ( 28.45%)
Lat 50.00th-qrtle-16 65.00 ( 0.00%) 64.00 ( 1.54%)
Lat 75.00th-qrtle-16 77.00 ( 0.00%) 71.00 ( 7.79%)
Lat 90.00th-qrtle-16 83.00 ( 0.00%) 82.00 ( 1.20%)
Lat 95.00th-qrtle-16 87.00 ( 0.00%) 87.00 ( 0.00%)
Lat 99.00th-qrtle-16 95.00 ( 0.00%) 96.00 ( -1.05%)
Lat 99.50th-qrtle-16 99.00 ( 0.00%) 103.00 ( -4.04%)
Lat 99.90th-qrtle-16 104.00 ( 0.00%) 122.00 ( -17.31%)
Lat 50.00th-qrtle-32 71.00 ( 0.00%) 73.00 ( -2.82%)
Lat 75.00th-qrtle-32 91.00 ( 0.00%) 92.00 ( -1.10%)
Lat 90.00th-qrtle-32 108.00 ( 0.00%) 107.00 ( 0.93%)
Lat 95.00th-qrtle-32 118.00 ( 0.00%) 115.00 ( 2.54%)
Lat 99.00th-qrtle-32 134.00 ( 0.00%) 129.00 ( 3.73%)
Lat 99.50th-qrtle-32 138.00 ( 0.00%) 133.00 ( 3.62%)
Lat 99.90th-qrtle-32 149.00 ( 0.00%) 146.00 ( 2.01%)
Lat 50.00th-qrtle-39 83.00 ( 0.00%) 81.00 ( 2.41%)
Lat 75.00th-qrtle-39 105.00 ( 0.00%) 102.00 ( 2.86%)
Lat 90.00th-qrtle-39 120.00 ( 0.00%) 119.00 ( 0.83%)
Lat 95.00th-qrtle-39 129.00 ( 0.00%) 128.00 ( 0.78%)
Lat 99.00th-qrtle-39 153.00 ( 0.00%) 149.00 ( 2.61%)
Lat 99.50th-qrtle-39 166.00 ( 0.00%) 156.00 ( 6.02%)
Lat 99.90th-qrtle-39 12304.00 ( 0.00%) 12848.00 ( -4.42%)
When heavily loaded (e.g. 99.50th-qrtle-39 indicates 39 threads), there
are small gains in many cases. Otherwise it depends on the quartile used
where it can be bad -- e.g. 75.00th-qrtle-2. However, even these results
are probably a co-incidence. For this workload, much depends on what node
the threads get placed on and their relative locality and not wakeups from
interrupt context. A larger component on how it behaves would be automatic
NUMA balancing where a fault incurred to measure locality would be a much
larger contributer to latency than the wakeup path.
This is the results from an almost identical machine that happened to run
the same test. They only differ in terms of storage which is irrelevant
for this test.
4.15.0-rc3 4.15.0-rc3
vanilla noirq-v1r1
Lat 50.00th-qrtle-1 41.00 ( 0.00%) 41.00 ( 0.00%)
Lat 75.00th-qrtle-1 42.00 ( 0.00%) 42.00 ( 0.00%)
Lat 90.00th-qrtle-1 44.00 ( 0.00%) 43.00 ( 2.27%)
Lat 95.00th-qrtle-1 53.00 ( 0.00%) 45.00 ( 15.09%)
Lat 99.00th-qrtle-1 59.00 ( 0.00%) 58.00 ( 1.69%)
Lat 99.50th-qrtle-1 60.00 ( 0.00%) 59.00 ( 1.67%)
Lat 99.90th-qrtle-1 86.00 ( 0.00%) 61.00 ( 29.07%)
Lat 50.00th-qrtle-2 52.00 ( 0.00%) 41.00 ( 21.15%)
Lat 75.00th-qrtle-2 57.00 ( 0.00%) 46.00 ( 19.30%)
Lat 90.00th-qrtle-2 60.00 ( 0.00%) 53.00 ( 11.67%)
Lat 95.00th-qrtle-2 62.00 ( 0.00%) 57.00 ( 8.06%)
Lat 99.00th-qrtle-2 73.00 ( 0.00%) 68.00 ( 6.85%)
Lat 99.50th-qrtle-2 74.00 ( 0.00%) 71.00 ( 4.05%)
Lat 99.90th-qrtle-2 90.00 ( 0.00%) 75.00 ( 16.67%)
Lat 50.00th-qrtle-4 57.00 ( 0.00%) 52.00 ( 8.77%)
Lat 75.00th-qrtle-4 60.00 ( 0.00%) 58.00 ( 3.33%)
Lat 90.00th-qrtle-4 62.00 ( 0.00%) 62.00 ( 0.00%)
Lat 95.00th-qrtle-4 65.00 ( 0.00%) 65.00 ( 0.00%)
Lat 99.00th-qrtle-4 76.00 ( 0.00%) 75.00 ( 1.32%)
Lat 99.50th-qrtle-4 77.00 ( 0.00%) 77.00 ( 0.00%)
Lat 99.90th-qrtle-4 87.00 ( 0.00%) 81.00 ( 6.90%)
Lat 50.00th-qrtle-8 59.00 ( 0.00%) 57.00 ( 3.39%)
Lat 75.00th-qrtle-8 63.00 ( 0.00%) 62.00 ( 1.59%)
Lat 90.00th-qrtle-8 66.00 ( 0.00%) 67.00 ( -1.52%)
Lat 95.00th-qrtle-8 68.00 ( 0.00%) 70.00 ( -2.94%)
Lat 99.00th-qrtle-8 79.00 ( 0.00%) 80.00 ( -1.27%)
Lat 99.50th-qrtle-8 80.00 ( 0.00%) 84.00 ( -5.00%)
Lat 99.90th-qrtle-8 84.00 ( 0.00%) 90.00 ( -7.14%)
Lat 50.00th-qrtle-16 65.00 ( 0.00%) 65.00 ( 0.00%)
Lat 75.00th-qrtle-16 77.00 ( 0.00%) 75.00 ( 2.60%)
Lat 90.00th-qrtle-16 84.00 ( 0.00%) 83.00 ( 1.19%)
Lat 95.00th-qrtle-16 88.00 ( 0.00%) 87.00 ( 1.14%)
Lat 99.00th-qrtle-16 97.00 ( 0.00%) 96.00 ( 1.03%)
Lat 99.50th-qrtle-16 100.00 ( 0.00%) 104.00 ( -4.00%)
Lat 99.90th-qrtle-16 110.00 ( 0.00%) 126.00 ( -14.55%)
Lat 50.00th-qrtle-32 70.00 ( 0.00%) 71.00 ( -1.43%)
Lat 75.00th-qrtle-32 92.00 ( 0.00%) 94.00 ( -2.17%)
Lat 90.00th-qrtle-32 110.00 ( 0.00%) 110.00 ( 0.00%)
Lat 95.00th-qrtle-32 121.00 ( 0.00%) 118.00 ( 2.48%)
Lat 99.00th-qrtle-32 135.00 ( 0.00%) 137.00 ( -1.48%)
Lat 99.50th-qrtle-32 140.00 ( 0.00%) 146.00 ( -4.29%)
Lat 99.90th-qrtle-32 150.00 ( 0.00%) 160.00 ( -6.67%)
Lat 50.00th-qrtle-39 80.00 ( 0.00%) 71.00 ( 11.25%)
Lat 75.00th-qrtle-39 102.00 ( 0.00%) 91.00 ( 10.78%)
Lat 90.00th-qrtle-39 118.00 ( 0.00%) 108.00 ( 8.47%)
Lat 95.00th-qrtle-39 128.00 ( 0.00%) 117.00 ( 8.59%)
Lat 99.00th-qrtle-39 149.00 ( 0.00%) 133.00 ( 10.74%)
Lat 99.50th-qrtle-39 160.00 ( 0.00%) 139.00 ( 13.12%)
Lat 99.90th-qrtle-39 13808.00 ( 0.00%) 4920.00 ( 64.37%)
Despite being nearly identical, it showed a variety of major gains so
I'm not convinced that heavy emphasis should be placed on this particular
workload in terms of evaluating this particular patch. Further evidence of
this is the fact that testing on a UMA machine showed small gains/losses
even though the patch should be a no-op on UMA.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171219085947.13136-2-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since the remote cpufreq callback work, the cpufreq_update_util() call can happen
from remote CPUs. The comment about local CPUs is thus obsolete. Update it
accordingly.
Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Android Kernel <kernel-team@android.com>
Cc: Atish Patra <atish.patra@oracle.com>
Cc: Chris Redpath <Chris.Redpath@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: EAS Dev <eas-dev@lists.linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Ramussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Rohit Jain <rohit.k.jain@oracle.com>
Cc: Saravana Kannan <skannan@quicinc.com>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vikram Mulukutla <markivx@codeaurora.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/20171215153944.220146-2-joelaf@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
find_idlest_group_cpu() goes through CPUs of a group previous selected by
find_idlest_group(). find_idlest_group() returns NULL if the local group is the
selected one and doesn't execute find_idlest_group_cpu if the group to which
'cpu' belongs to is chosen. So we're always guaranteed to call
find_idlest_group_cpu() with a group to which 'cpu' is non-local.
This makes one of the conditions in find_idlest_group_cpu() an impossible one,
which we can get rid off.
Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Brendan Jackman <brendan.jackman@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Android Kernel <kernel-team@android.com>
Cc: Atish Patra <atish.patra@oracle.com>
Cc: Chris Redpath <Chris.Redpath@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: EAS Dev <eas-dev@lists.linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Ramussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Rohit Jain <rohit.k.jain@oracle.com>
Cc: Saravana Kannan <skannan@quicinc.com>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vikram Mulukutla <markivx@codeaurora.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20171215153944.220146-3-joelaf@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Initializing sg_cpu->flags to SCHED_CPUFREQ_RT has no obvious benefit.
The flags field wouldn't be used until the utilization update handler is
called for the first time, and once that is called we will overwrite
flags anyway.
Initialize it to 0.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael Wysocki <rjw@rjwysocki.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: dietmar.eggemann@arm.com
Cc: joelaf@google.com
Cc: morten.rasmussen@arm.com
Cc: tkjos@android.com
Link: http://lkml.kernel.org/r/763feda6424ced8486b25a0c52979634e6104478.1513158452.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
capacity_spare_wake() in the slow path influences choice of idlest groups,
as we search for groups with maximum spare capacity. In scenarios where
RT pressure is high, a sub optimal group can be chosen and hurt
performance of the task being woken up.
Fix this by using capacity_of() instead of capacity_orig_of() in capacity_spare_wake().
Tests results from improvements with this change are below. More tests
were also done by myself and Matt Fleming to ensure no degradation in
different benchmarks.
1) Rohit ran barrier.c test (details below) with following improvements:
------------------------------------------------------------------------
This was Rohit's original use case for a patch he posted at [1] however
from his recent tests he showed my patch can replace his slow path
changes [1] and there's no need to selectively scan/skip CPUs in
find_idlest_group_cpu in the slow path to get the improvement he sees.
barrier.c (open_mp code) as a micro-benchmark. It does a number of
iterations and barrier sync at the end of each for loop.
Here barrier,c is running in along with ping on CPU 0 and 1 as:
'ping -l 10000 -q -s 10 -f hostX'
barrier.c can be found at:
http://www.spinics.net/lists/kernel/msg2506955.html
Following are the results for the iterations per second with this
micro-benchmark (higher is better), on a 44 core, 2 socket 88 Threads
Intel x86 machine:
+--------+------------------+---------------------------+
|Threads | Without patch | With patch |
| | | |
+--------+--------+---------+-----------------+---------+
| | Mean | Std Dev | Mean | Std Dev |
+--------+--------+---------+-----------------+---------+
|1 | 539.36 | 60.16 | 572.54 (+6.15%) | 40.95 |
|2 | 481.01 | 19.32 | 530.64 (+10.32%)| 56.16 |
|4 | 474.78 | 22.28 | 479.46 (+0.99%) | 18.89 |
|8 | 450.06 | 24.91 | 447.82 (-0.50%) | 12.36 |
|16 | 436.99 | 22.57 | 441.88 (+1.12%) | 7.39 |
|32 | 388.28 | 55.59 | 429.4 (+10.59%)| 31.14 |
|64 | 314.62 | 6.33 | 311.81 (-0.89%) | 11.99 |
+--------+--------+---------+-----------------+---------+
2) ping+hackbench test on bare-metal sever (by Rohit)
-----------------------------------------------------
Here hackbench is running in threaded mode along
with, running ping on CPU 0 and 1 as:
'ping -l 10000 -q -s 10 -f hostX'
This test is running on 2 socket, 20 core and 40 threads Intel x86
machine:
Number of loops is 10000 and runtime is in seconds (Lower is better).
+--------------+-----------------+--------------------------+
|Task Groups | Without patch | With patch |
| +-------+---------+----------------+---------+
|(Groups of 40)| Mean | Std Dev | Mean | Std Dev |
+--------------+-------+---------+----------------+---------+
|1 | 0.851 | 0.007 | 0.828 (+2.77%)| 0.032 |
|2 | 1.083 | 0.203 | 1.087 (-0.37%)| 0.246 |
|4 | 1.601 | 0.051 | 1.611 (-0.62%)| 0.055 |
|8 | 2.837 | 0.060 | 2.827 (+0.35%)| 0.031 |
|16 | 5.139 | 0.133 | 5.107 (+0.63%)| 0.085 |
|25 | 7.569 | 0.142 | 7.503 (+0.88%)| 0.143 |
+--------------+-------+---------+----------------+---------+
[1] https://patchwork.kernel.org/patch/9991635/
Matt Fleming also ran several different hackbench tests and cyclic test
to santiy-check that the patch doesn't harm other usecases.
Tested-by: Matt Fleming <matt@codeblueprint.co.uk>
Tested-by: Rohit Jain <rohit.k.jain@oracle.com>
Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Atish Patra <atish.patra@oracle.com>
Cc: Brendan Jackman <brendan.jackman@arm.com>
Cc: Chris Redpath <Chris.Redpath@arm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Ramussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Saravana Kannan <skannan@quicinc.com>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vikram Mulukutla <markivx@codeaurora.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20171214212158.188190-1-joelaf@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Utilization and capacity are tracked as 'unsigned long', however some
functions using them return an 'int' which is ultimately assigned back to
'unsigned long' variables.
Since there is not scope on using a different and signed type,
consolidate the signature of functions returning utilization to always
use the native type.
This change improves code consistency, and it also benefits
code paths where utilizations should be clamped by avoiding
further type conversions or ugly type casts.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chris Redpath <chris.redpath@arm.com>
Reviewed-by: Brendan Jackman <brendan.jackman@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@android.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20171205171018.9203-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The prepare_lock_switch() function has an unused parameter, and also the
function name was not descriptive. To improve readability and remove
the extra parameter, do the following changes:
* Move prepare_lock_switch() from kernel/sched/sched.h to
kernel/sched/core.c, rename it to prepare_task(), and remove the
unused parameter.
* Split the smp_store_release() out from finish_lock_switch() to a
function named finish_task.
* Comments ajdustments.
Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171215140603.gxe5i2y6fg5ojfpp@smtp.gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
smp_call_function_many() requires disabling preemption around the call.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: <stable@vger.kernel.org> # v4.14+
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Andrew Hunter <ahh@google.com>
Cc: Avi Kivity <avi@scylladb.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maged Michael <maged.michael@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171215192310.25293-1-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull RCU updates from Paul E. McKenney:
- Updates to use cond_resched() instead of cond_resched_rcu_qs()
where feasible (currently everywhere except in kernel/rcu and
in kernel/torture.c). Also a couple of fixes to avoid sending
IPIs to offline CPUs.
- Updates to simplify RCU's dyntick-idle handling.
- Updates to remove almost all uses of smp_read_barrier_depends()
and read_barrier_depends().
- Miscellaneous fixes.
- Torture-test updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since the recent remote cpufreq callback work, its possible that a cpufreq
update is triggered from a remote CPU. For single policies however, the current
code uses the local CPU when trying to determine if the remote sg_cpu entered
idle or is busy. This is incorrect. To remedy this, compare with the nohz tick
idle_calls counter of the remote CPU.
Fixes: 674e75411f (sched: cpufreq: Allow remote cpufreq callbacks)
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Joel Fernandes <joelaf@google.com>
Cc: 4.14+ <stable@vger.kernel.org> # 4.14+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Daniel Wagner reported a crash on the BeagleBone Black SoC.
This is a single CPU architecture, and does not have a functional
arch_send_call_function_single_ipi() implementation which can crash
the kernel if that is called.
As it only has one CPU, it shouldn't be called, but if the kernel is
compiled for SMP, the push/pull RT scheduling logic now calls it for
irq_work if the one CPU is overloaded, it can use that function to call
itself and crash the kernel.
Ideally, we should disable the SCHED_FEAT(RT_PUSH_IPI) if the system
only has a single CPU. But SCHED_FEAT is a constant if sched debugging
is turned off. Another fix can also be used, and this should also help
with normal SMP machines. That is, do not initiate the pull code if
there's only one RT overloaded CPU, and that CPU happens to be the
current CPU that is scheduling in a lower priority task.
Even on a system with many CPUs, if there's many RT tasks waiting to
run on a single CPU, and that CPU schedules in another RT task of lower
priority, it will initiate the PULL logic in case there's a higher
priority RT task on another CPU that is waiting to run. But if there is
no other CPU with waiting RT tasks, it will initiate the RT pull logic
on itself (as it still has RT tasks waiting to run). This is a wasted
effort.
Not only does this help with SMP code where the current CPU is the only
one with RT overloaded tasks, it should also solve the issue that
Daniel encountered, because it will prevent the PULL logic from
executing, as there's only one CPU on the system, and the check added
here will cause it to exit the RT pull code.
Reported-by: Daniel Wagner <wagi@monom.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: stable@vger.kernel.org
Fixes: 4bdced5c9 ("sched/rt: Simplify the IPI based RT balancing logic")
Link: http://lkml.kernel.org/r/20171202130454.4cbbfe8d@vmware.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix the following kernel-doc warnings after code restructuring:
../kernel/sched/core.c:5113: warning: No description found for parameter 't'
../kernel/sched/core.c:5113: warning: Excess function parameter 'interval' description in 'sched_rr_get_interval'
get rid of set_fs()")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: abca5fc535 ("sched_rr_get_interval(): move compat to native,
Link: http://lkml.kernel.org/r/995c6ded-b32e-bbe4-d9f5-4d42d121aff1@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move local "sched.h" include to the bottom. sched.h defines
several macros that are getting redefined in ARCH-specific
code, for instance, finish_arch_post_lock_switch() and
prepare_arch_switch(), so we need ARCH-specific definitions
to come in first.
Link: http://lkml.kernel.org/r/20171208082422.5021-1-sergey.senozhatsky@gmail.com
To: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: linux-pm@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: linux-mm@kvack.org
Suggested-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Autogroup does not seem to use any of kallsyms functions/defines.
Link: http://lkml.kernel.org/r/20171208025616.16267-2-sergey.senozhatsky@gmail.com
To: Andrew Morton <akpm@linux-foundation.org>
To: Michal Hocko <mhocko@suse.com>
To: Rafael Wysocki <rjw@rjwysocki.net>
To: Len Brown <len.brown@intel.com>
To: Bjorn Helgaas <bhelgaas@google.com>
To: Vlastimil Babka <vbabka@suse.cz>
To: Tejun Heo <tj@kernel.org>
To: Lai Jiangshan <jiangshanlai@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: linux-pm@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Unlike running, the runnable part can't be directly propagated through
the hierarchy when we migrate a task. The main reason is that runnable
time can be shared with other sched_entities that stay on the rq and
this runnable time will also remain on prev cfs_rq and must not be
removed.
Instead, we can estimate what should be the new runnable of the prev
cfs_rq and check that this estimation stay in a possible range. The
prop_runnable_sum is a good estimation when adding runnable_sum but
fails most often when we remove it. Instead, we could use the formula
below instead:
gcfs_rq's runnable_sum = gcfs_rq->avg.load_sum / gcfs_rq->load.weight
which assumes that tasks are equally runnable which is not true but
easy to compute.
Beside these estimates, we have several simple rules that help us to filter
out wrong ones:
- ge->avg.runnable_sum <= than LOAD_AVG_MAX
- ge->avg.runnable_sum >= ge->avg.running_sum (ge->avg.util_sum << LOAD_AVG_MAX)
- ge->avg.runnable_sum can't increase when we detach a task
The effect of these fixes is better cgroups balancing.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Chris Mason <clm@fb.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/1510842112-21028-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The following cleanup commit:
50816c4899 ("sched/wait: Standardize internal naming of wait-queue entries")
... unintentionally changed the behavior of add_wait_queue() from
inserting the wait entry at the head of the wait queue to the tail
of the wait queue.
Beyond a negative performance impact this change in behavior
theoretically also breaks wait queues which mix exclusive and
non-exclusive waiters, as non-exclusive waiters will not be
woken up if they are queued behind enough exclusive waiters.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@fb.com
Fixes: ("sched/wait: Standardize internal naming of wait-queue entries")
Link: http://lkml.kernel.org/r/a16c8ccffd39bd08fdaa45a5192294c784b803a7.1512544324.git.osandov@fb.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The rcutorture test suite occasionally provokes a splat due to invoking
rt_mutex_lock() which needs to boost the priority of a task currently
sitting on a runqueue that belongs to an offline CPU:
WARNING: CPU: 0 PID: 12 at /home/paulmck/public_git/linux-rcu/arch/x86/kernel/smp.c:128 native_smp_send_reschedule+0x37/0x40
Modules linked in:
CPU: 0 PID: 12 Comm: rcub/7 Not tainted 4.14.0-rc4+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
task: ffff9ed3de5f8cc0 task.stack: ffffbbf80012c000
RIP: 0010:native_smp_send_reschedule+0x37/0x40
RSP: 0018:ffffbbf80012fd10 EFLAGS: 00010082
RAX: 000000000000002f RBX: ffff9ed3dd9cb300 RCX: 0000000000000004
RDX: 0000000080000004 RSI: 0000000000000086 RDI: 00000000ffffffff
RBP: ffffbbf80012fd10 R08: 000000000009da7a R09: 0000000000007b9d
R10: 0000000000000001 R11: ffffffffbb57c2cd R12: 000000000000000d
R13: ffff9ed3de5f8cc0 R14: 0000000000000061 R15: ffff9ed3ded59200
FS: 0000000000000000(0000) GS:ffff9ed3dea00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000080686f0 CR3: 000000001b9e0000 CR4: 00000000000006f0
Call Trace:
resched_curr+0x61/0xd0
switched_to_rt+0x8f/0xa0
rt_mutex_setprio+0x25c/0x410
task_blocks_on_rt_mutex+0x1b3/0x1f0
rt_mutex_slowlock+0xa9/0x1e0
rt_mutex_lock+0x29/0x30
rcu_boost_kthread+0x127/0x3c0
kthread+0x104/0x140
? rcu_report_unblock_qs_rnp+0x90/0x90
? kthread_create_on_node+0x40/0x40
ret_from_fork+0x22/0x30
Code: f0 00 0f 92 c0 84 c0 74 14 48 8b 05 34 74 c5 00 be fd 00 00 00 ff 90 a0 00 00 00 5d c3 89 fe 48 c7 c7 a0 c6 fc b9 e8 d5 b5 06 00 <0f> ff 5d c3 0f 1f 44 00 00 8b 05 a2 d1 13 02 85 c0 75 38 55 48
But the target task's priority has already been adjusted, so the only
purpose of switched_to_rt() invoking resched_curr() is to wake up the
CPU running some task that needs to be preempted by the boosted task.
But the CPU is offline, which presumably means that the task must be
migrated to some other CPU, and that this other CPU will undertake any
needed preemption at the time of migration. Because the runqueue lock
is held when resched_curr() is invoked, we know that the boosted task
cannot go anywhere, so it is not necessary to invoke resched_curr()
in this particular case.
This commit therefore makes switched_to_rt() refrain from invoking
resched_curr() when the target CPU is offline.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
The rcutorture test suite occasionally provokes a splat due to invoking
resched_cpu() on an offline CPU:
WARNING: CPU: 2 PID: 8 at /home/paulmck/public_git/linux-rcu/arch/x86/kernel/smp.c:128 native_smp_send_reschedule+0x37/0x40
Modules linked in:
CPU: 2 PID: 8 Comm: rcu_preempt Not tainted 4.14.0-rc4+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
task: ffff902ede9daf00 task.stack: ffff96c50010c000
RIP: 0010:native_smp_send_reschedule+0x37/0x40
RSP: 0018:ffff96c50010fdb8 EFLAGS: 00010096
RAX: 000000000000002e RBX: ffff902edaab4680 RCX: 0000000000000003
RDX: 0000000080000003 RSI: 0000000000000000 RDI: 00000000ffffffff
RBP: ffff96c50010fdb8 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 00000000299f36ae R12: 0000000000000001
R13: ffffffff9de64240 R14: 0000000000000001 R15: ffffffff9de64240
FS: 0000000000000000(0000) GS:ffff902edfc80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f7d4c642 CR3: 000000001e0e2000 CR4: 00000000000006e0
Call Trace:
resched_curr+0x8f/0x1c0
resched_cpu+0x2c/0x40
rcu_implicit_dynticks_qs+0x152/0x220
force_qs_rnp+0x147/0x1d0
? sync_rcu_exp_select_cpus+0x450/0x450
rcu_gp_kthread+0x5a9/0x950
kthread+0x142/0x180
? force_qs_rnp+0x1d0/0x1d0
? kthread_create_on_node+0x40/0x40
ret_from_fork+0x27/0x40
Code: 14 01 0f 92 c0 84 c0 74 14 48 8b 05 14 4f f4 00 be fd 00 00 00 ff 90 a0 00 00 00 5d c3 89 fe 48 c7 c7 38 89 ca 9d e8 e5 56 08 00 <0f> ff 5d c3 0f 1f 44 00 00 8b 05 52 9e 37 02 85 c0 75 38 55 48
---[ end trace 26df9e5df4bba4ac ]---
This splat cannot be generated by expedited grace periods because they
always invoke resched_cpu() on the current CPU, which is good because
expedited grace periods require that resched_cpu() unconditionally
succeed. However, other parts of RCU can tolerate resched_cpu() acting
as a no-op, at least as long as it doesn't happen too often.
This commit therefore makes resched_cpu() invoke resched_curr() only if
the CPU is either online or is the current CPU.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Pull compat and uaccess updates from Al Viro:
- {get,put}_compat_sigset() series
- assorted compat ioctl stuff
- more set_fs() elimination
- a few more timespec64 conversions
- several removals of pointless access_ok() in places where it was
followed only by non-__ variants of primitives
* 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (24 commits)
coredump: call do_unlinkat directly instead of sys_unlink
fs: expose do_unlinkat for built-in callers
ext4: take handling of EXT4_IOC_GROUP_ADD into a helper, get rid of set_fs()
ipmi: get rid of pointless access_ok()
pi433: sanitize ioctl
cxlflash: get rid of pointless access_ok()
mtdchar: get rid of pointless access_ok()
r128: switch compat ioctls to drm_ioctl_kernel()
selection: get rid of field-by-field copyin
VT_RESIZEX: get rid of field-by-field copyin
i2c compat ioctls: move to ->compat_ioctl()
sched_rr_get_interval(): move compat to native, get rid of set_fs()
mips: switch to {get,put}_compat_sigset()
sparc: switch to {get,put}_compat_sigset()
s390: switch to {get,put}_compat_sigset()
ppc: switch to {get,put}_compat_sigset()
parisc: switch to {get,put}_compat_sigset()
get_compat_sigset()
get rid of {get,put}_compat_itimerspec()
io_getevents: Use timespec64 to represent timeouts
...
-----BEGIN PGP SIGNATURE-----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=3vy0
-----END PGP SIGNATURE-----
Merge tag 'afs-next-20171113' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull AFS updates from David Howells:
"kAFS filesystem driver overhaul.
The major points of the overhaul are:
(1) Preliminary groundwork is laid for supporting network-namespacing
of kAFS. The remainder of the namespacing work requires some way
to pass namespace information to submounts triggered by an
automount. This requires something like the mount overhaul that's
in progress.
(2) sockaddr_rxrpc is used in preference to in_addr for holding
addresses internally and add support for talking to the YFS VL
server. With this, kAFS can do everything over IPv6 as well as
IPv4 if it's talking to servers that support it.
(3) Callback handling is overhauled to be generally passive rather
than active. 'Callbacks' are promises by the server to tell us
about data and metadata changes. Callbacks are now checked when
we next touch an inode rather than actively going and looking for
it where possible.
(4) File access permit caching is overhauled to store the caching
information per-inode rather than per-directory, shared over
subordinate files. Whilst older AFS servers only allow ACLs on
directories (shared to the files in that directory), newer AFS
servers break that restriction.
To improve memory usage and to make it easier to do mass-key
removal, permit combinations are cached and shared.
(5) Cell database management is overhauled to allow lighter locks to
be used and to make cell records autonomous state machines that
look after getting their own DNS records and cleaning themselves
up, in particular preventing races in acquiring and relinquishing
the fscache token for the cell.
(6) Volume caching is overhauled. The afs_vlocation record is got rid
of to simplify things and the superblock is now keyed on the cell
and the numeric volume ID only. The volume record is tied to a
superblock and normal superblock management is used to mediate
the lifetime of the volume fscache token.
(7) File server record caching is overhauled to make server records
independent of cells and volumes. A server can be in multiple
cells (in such a case, the administrator must make sure that the
VL services for all cells correctly reflect the volumes shared
between those cells).
Server records are now indexed using the UUID of the server
rather than the address since a server can have multiple
addresses.
(8) File server rotation is overhauled to handle VMOVED, VBUSY (and
similar), VOFFLINE and VNOVOL indications and to handle rotation
both of servers and addresses of those servers. The rotation will
also wait and retry if the server says it is busy.
(9) Data writeback is overhauled. Each inode no longer stores a list
of modified sections tagged with the key that authorised it in
favour of noting the modified region of a page in page->private
and storing a list of keys that made modifications in the inode.
This simplifies things and allows other keys to be used to
actually write to the server if a key that made a modification
becomes useless.
(10) Writable mmap() is implemented. This allows a kernel to be build
entirely on AFS.
Note that Pre AFS-3.4 servers are no longer supported, though this can
be added back if necessary (AFS-3.4 was released in 1998)"
* tag 'afs-next-20171113' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: (35 commits)
afs: Protect call->state changes against signals
afs: Trace page dirty/clean
afs: Implement shared-writeable mmap
afs: Get rid of the afs_writeback record
afs: Introduce a file-private data record
afs: Use a dynamic port if 7001 is in use
afs: Fix directory read/modify race
afs: Trace the sending of pages
afs: Trace the initiation and completion of client calls
afs: Fix documentation on # vs % prefix in mount source specification
afs: Fix total-length calculation for multiple-page send
afs: Only progress call state at end of Tx phase from rxrpc callback
afs: Make use of the YFS service upgrade to fully support IPv6
afs: Overhaul volume and server record caching and fileserver rotation
afs: Move server rotation code into its own file
afs: Add an address list concept
afs: Overhaul cell database management
afs: Overhaul permit caching
afs: Overhaul the callback handling
afs: Rename struct afs_call server member to cm_server
...
Pull cgroup updates from Tejun Heo:
"Cgroup2 cpu controller support is finally merged.
- Basic cpu statistics support to allow monitoring by default without
the CPU controller enabled.
- cgroup2 cpu controller support.
- /sys/kernel/cgroup files to help dealing with new / optional
features"
* 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: export list of cgroups v2 features using sysfs
cgroup: export list of delegatable control files using sysfs
cgroup: mark @cgrp __maybe_unused in cpu_stat_show()
MAINTAINERS: relocate cpuset.c
cgroup, sched: Move basic cpu stats from cgroup.stat to cpu.stat
sched: Implement interface for cgroup unified hierarchy
sched: Misc preps for cgroup unified hierarchy interface
sched/cputime: Add dummy cputime_adjust() implementation for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
cgroup: statically initialize init_css_set->dfl_cgrp
cgroup: Implement cgroup2 basic CPU usage accounting
cpuacct: Introduce cgroup_account_cputime[_field]()
sched/cputime: Expose cputime_adjust()
- Relocate the OPP (Operating Performance Points) framework to its
own directory under drivers/ and add support for power domain
performance states to it (Viresh Kumar).
- Modify the PM core, the PCI bus type and the ACPI PM domain to
support power management driver flags allowing device drivers to
specify their capabilities and preferences regarding the handling
of devices with enabled runtime PM during system suspend/resume
and clean up that code somewhat (Rafael Wysocki, Ulf Hansson).
- Add frequency-invariant accounting support to the task scheduler
on ARM and ARM64 (Dietmar Eggemann).
- Fix PM QoS device resume latency framework to prevent "no
restriction" requests from overriding requests with specific
requirements and drop the confusing PM_QOS_FLAG_REMOTE_WAKEUP
device PM QoS flag (Rafael Wysocki).
- Drop legacy class suspend/resume operations from the PM core
and drop legacy bus type suspend and resume callbacks from
ARM/locomo (Rafael Wysocki).
- Add min/max frequency support to devfreq and clean it up
somewhat (Chanwoo Choi).
- Rework wakeup support in the generic power domains (genpd)
framework and update some of its users accordingly (Geert
Uytterhoeven).
- Convert timers in the PM core to use timer_setup() (Kees Cook).
- Add support for exposing the SLP_S0 (Low Power S0 Idle)
residency counter based on the LPIT ACPI table on Intel
platforms (Srinivas Pandruvada).
- Add per-CPU PM QoS resume latency support to the ladder cpuidle
governor (Ramesh Thomas).
- Fix a deadlock between the wakeup notify handler and the
notifier removal in the ACPI core (Ville Syrjälä).
- Fix a cpufreq schedutil governor issue causing it to use
stale cached frequency values sometimes (Viresh Kumar).
- Fix an issue in the system suspend core support code causing
wakeup events detection to fail in some cases (Rajat Jain).
- Fix the generic power domains (genpd) framework to prevent
the PM core from using the direct-complete optimization with
it as that is guaranteed to fail (Ulf Hansson).
- Fix a minor issue in the cpuidle core and clean it up a bit
(Gaurav Jindal, Nicholas Piggin).
- Fix and clean up the intel_idle and ARM cpuidle drivers (Jason
Baron, Len Brown, Leo Yan).
- Fix a couple of minor issues in the OPP framework and clean it
up (Arvind Yadav, Fabio Estevam, Sudeep Holla, Tobias Jordan).
- Fix and clean up some cpufreq drivers and fix a minor issue in
the cpufreq statistics code (Arvind Yadav, Bhumika Goyal, Fabio
Estevam, Gautham Shenoy, Gustavo Silva, Marek Szyprowski, Masahiro
Yamada, Robert Jarzmik, Zumeng Chen).
- Fix minor issues in the system suspend and hibernation core, in
power management documentation and in the AVS (Adaptive Voltage
Scaling) framework (Helge Deller, Himanshu Jha, Joe Perches,
Rafael Wysocki).
- Fix some issues in the cpupower utility and document that Shuah
Khan is going to maintain it going forward (Prarit Bhargava,
Shuah Khan).
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2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=QTnx
-----END PGP SIGNATURE-----
Merge tag 'pm-4.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"There are no real big ticket items here this time.
The most noticeable change is probably the relocation of the OPP
(Operating Performance Points) framework to its own directory under
drivers/ as it has grown big enough for that. Also Viresh is now going
to maintain it and send pull requests for it to me, so you will see
this change in the git history going forward (but still not right
now).
Another noticeable set of changes is the modifications of the PM core,
the PCI subsystem and the ACPI PM domain to allow of more integration
between system-wide suspend/resume and runtime PM. For now it's just a
way to avoid resuming devices from runtime suspend unnecessarily
during system suspend (if the driver sets a flag to indicate its
readiness for that) and in the works is an analogous mechanism to
allow devices to stay suspended after system resume.
In addition to that, we have some changes related to supporting
frequency-invariant CPU utilization metrics in the scheduler and in
the schedutil cpufreq governor on ARM and changes to add support for
device performance states to the generic power domains (genpd)
framework.
The rest is mostly fixes and cleanups of various sorts.
Specifics:
- Relocate the OPP (Operating Performance Points) framework to its
own directory under drivers/ and add support for power domain
performance states to it (Viresh Kumar).
- Modify the PM core, the PCI bus type and the ACPI PM domain to
support power management driver flags allowing device drivers to
specify their capabilities and preferences regarding the handling
of devices with enabled runtime PM during system suspend/resume and
clean up that code somewhat (Rafael Wysocki, Ulf Hansson).
- Add frequency-invariant accounting support to the task scheduler on
ARM and ARM64 (Dietmar Eggemann).
- Fix PM QoS device resume latency framework to prevent "no
restriction" requests from overriding requests with specific
requirements and drop the confusing PM_QOS_FLAG_REMOTE_WAKEUP
device PM QoS flag (Rafael Wysocki).
- Drop legacy class suspend/resume operations from the PM core and
drop legacy bus type suspend and resume callbacks from ARM/locomo
(Rafael Wysocki).
- Add min/max frequency support to devfreq and clean it up somewhat
(Chanwoo Choi).
- Rework wakeup support in the generic power domains (genpd)
framework and update some of its users accordingly (Geert
Uytterhoeven).
- Convert timers in the PM core to use timer_setup() (Kees Cook).
- Add support for exposing the SLP_S0 (Low Power S0 Idle) residency
counter based on the LPIT ACPI table on Intel platforms (Srinivas
Pandruvada).
- Add per-CPU PM QoS resume latency support to the ladder cpuidle
governor (Ramesh Thomas).
- Fix a deadlock between the wakeup notify handler and the notifier
removal in the ACPI core (Ville Syrjälä).
- Fix a cpufreq schedutil governor issue causing it to use stale
cached frequency values sometimes (Viresh Kumar).
- Fix an issue in the system suspend core support code causing wakeup
events detection to fail in some cases (Rajat Jain).
- Fix the generic power domains (genpd) framework to prevent the PM
core from using the direct-complete optimization with it as that is
guaranteed to fail (Ulf Hansson).
- Fix a minor issue in the cpuidle core and clean it up a bit (Gaurav
Jindal, Nicholas Piggin).
- Fix and clean up the intel_idle and ARM cpuidle drivers (Jason
Baron, Len Brown, Leo Yan).
- Fix a couple of minor issues in the OPP framework and clean it up
(Arvind Yadav, Fabio Estevam, Sudeep Holla, Tobias Jordan).
- Fix and clean up some cpufreq drivers and fix a minor issue in the
cpufreq statistics code (Arvind Yadav, Bhumika Goyal, Fabio
Estevam, Gautham Shenoy, Gustavo Silva, Marek Szyprowski, Masahiro
Yamada, Robert Jarzmik, Zumeng Chen).
- Fix minor issues in the system suspend and hibernation core, in
power management documentation and in the AVS (Adaptive Voltage
Scaling) framework (Helge Deller, Himanshu Jha, Joe Perches, Rafael
Wysocki).
- Fix some issues in the cpupower utility and document that Shuah
Khan is going to maintain it going forward (Prarit Bhargava, Shuah
Khan)"
* tag 'pm-4.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (88 commits)
tools/power/cpupower: add libcpupower.so.0.0.1 to .gitignore
tools/power/cpupower: Add 64 bit library detection
intel_idle: Graceful probe failure when MWAIT is disabled
cpufreq: schedutil: Reset cached_raw_freq when not in sync with next_freq
freezer: Fix typo in freezable_schedule_timeout() comment
PM / s2idle: Clear the events_check_enabled flag
cpufreq: stats: Handle the case when trans_table goes beyond PAGE_SIZE
cpufreq: arm_big_little: make cpufreq_arm_bL_ops structures const
cpufreq: arm_big_little: make function arguments and structure pointer const
cpuidle: Avoid assignment in if () argument
cpuidle: Clean up cpuidle_enable_device() error handling a bit
ACPI / PM: Fix acpi_pm_notifier_lock vs flush_workqueue() deadlock
PM / Domains: Fix genpd to deal with drivers returning 1 from ->prepare()
cpuidle: ladder: Add per CPU PM QoS resume latency support
PM / QoS: Fix device resume latency framework
PM / domains: Rework governor code to be more consistent
PM / Domains: Remove gpd_dev_ops.active_wakeup() callback
soc: rockchip: power-domain: Use GENPD_FLAG_ACTIVE_WAKEUP
soc: mediatek: Use GENPD_FLAG_ACTIVE_WAKEUP
ARM: shmobile: pm-rmobile: Use GENPD_FLAG_ACTIVE_WAKEUP
...
Pull scheduler updates from Ingo Molnar:
"The main updates in this cycle were:
- Group balancing enhancements and cleanups (Brendan Jackman)
- Move CPU isolation related functionality into its separate
kernel/sched/isolation.c file, with related 'housekeeping_*()'
namespace and nomenclature et al. (Frederic Weisbecker)
- Improve the interactive/cpu-intense fairness calculation (Josef
Bacik)
- Improve the PELT code and related cleanups (Peter Zijlstra)
- Improve the logic of pick_next_task_fair() (Uladzislau Rezki)
- Improve the RT IPI based balancing logic (Steven Rostedt)
- Various micro-optimizations:
- better !CONFIG_SCHED_DEBUG optimizations (Patrick Bellasi)
- better idle loop (Cheng Jian)
- ... plus misc fixes, cleanups and updates"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds
sched/sysctl: Fix attributes of some extern declarations
sched/isolation: Document isolcpus= boot parameter flags, mark it deprecated
sched/isolation: Add basic isolcpus flags
sched/isolation: Move isolcpus= handling to the housekeeping code
sched/isolation: Handle the nohz_full= parameter
sched/isolation: Introduce housekeeping flags
sched/isolation: Split out new CONFIG_CPU_ISOLATION=y config from CONFIG_NO_HZ_FULL
sched/isolation: Rename is_housekeeping_cpu() to housekeeping_cpu()
sched/isolation: Use its own static key
sched/isolation: Make the housekeeping cpumask private
sched/isolation: Provide a dynamic off-case to housekeeping_any_cpu()
sched/isolation, watchdog: Use housekeeping_cpumask() instead of ad-hoc version
sched/isolation: Move housekeeping related code to its own file
sched/idle: Micro-optimize the idle loop
sched/isolcpus: Fix "isolcpus=" boot parameter handling when !CONFIG_CPUMASK_OFFSTACK
x86/tsc: Append the 'tsc=' description for the 'tsc=unstable' boot parameter
sched/rt: Simplify the IPI based RT balancing logic
block/ioprio: Use a helper to check for RT prio
sched/rt: Add a helper to test for a RT task
...
Pull core locking updates from Ingo Molnar:
"The main changes in this cycle are:
- Another attempt at enabling cross-release lockdep dependency
tracking (automatically part of CONFIG_PROVE_LOCKING=y), this time
with better performance and fewer false positives. (Byungchul Park)
- Introduce lockdep_assert_irqs_enabled()/disabled() and convert
open-coded equivalents to lockdep variants. (Frederic Weisbecker)
- Add down_read_killable() and use it in the VFS's iterate_dir()
method. (Kirill Tkhai)
- Convert remaining uses of ACCESS_ONCE() to
READ_ONCE()/WRITE_ONCE(). Most of the conversion was Coccinelle
driven. (Mark Rutland, Paul E. McKenney)
- Get rid of lockless_dereference(), by strengthening Alpha atomics,
strengthening READ_ONCE() with smp_read_barrier_depends() and thus
being able to convert users of lockless_dereference() to
READ_ONCE(). (Will Deacon)
- Various micro-optimizations:
- better PV qspinlocks (Waiman Long),
- better x86 barriers (Michael S. Tsirkin)
- better x86 refcounts (Kees Cook)
- ... plus other fixes and enhancements. (Borislav Petkov, Juergen
Gross, Miguel Bernal Marin)"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits)
locking/x86: Use LOCK ADD for smp_mb() instead of MFENCE
rcu: Use lockdep to assert IRQs are disabled/enabled
netpoll: Use lockdep to assert IRQs are disabled/enabled
timers/posix-cpu-timers: Use lockdep to assert IRQs are disabled/enabled
sched/clock, sched/cputime: Use lockdep to assert IRQs are disabled/enabled
irq_work: Use lockdep to assert IRQs are disabled/enabled
irq/timings: Use lockdep to assert IRQs are disabled/enabled
perf/core: Use lockdep to assert IRQs are disabled/enabled
x86: Use lockdep to assert IRQs are disabled/enabled
smp/core: Use lockdep to assert IRQs are disabled/enabled
timers/hrtimer: Use lockdep to assert IRQs are disabled/enabled
timers/nohz: Use lockdep to assert IRQs are disabled/enabled
workqueue: Use lockdep to assert IRQs are disabled/enabled
irq/softirqs: Use lockdep to assert IRQs are disabled/enabled
locking/lockdep: Add IRQs disabled/enabled assertion APIs: lockdep_assert_irqs_enabled()/disabled()
locking/pvqspinlock: Implement hybrid PV queued/unfair locks
locking/rwlocks: Fix comments
x86/paravirt: Set up the virt_spin_lock_key after static keys get initialized
block, locking/lockdep: Assign a lock_class per gendisk used for wait_for_completion()
workqueue: Remove now redundant lock acquisitions wrt. workqueue flushes
...
Pull RCU updates from Ingo Molnar:
"The main changes in this cycle are:
- Documentation updates
- RCU CPU stall-warning updates
- Torture-test updates
- Miscellaneous fixes
Size wise the biggest updates are to documentation. Excluding
documentation most of the code increase comes from a single commit
which expands debugging"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
srcu: Add parameters to SRCU docbook comments
doc: Rewrite confusing statement about memory barriers
memory-barriers.txt: Fix typo in pairing example
rcu/segcblist: Include rcupdate.h
rcu: Add extended-quiescent-state testing advice
rcu: Suppress lockdep false-positive ->boost_mtx complaints
rcu: Do not include rtmutex_common.h unconditionally
torture: Provide TMPDIR environment variable to specify tmpdir
rcutorture: Dump writer stack if stalled
rcutorture: Add interrupt-disable capability to stall-warning tests
rcu: Suppress RCU CPU stall warnings while dumping trace
rcu: Turn off tracing before dumping trace
rcu: Make RCU CPU stall warnings check for irq-disabled CPUs
sched,rcu: Make cond_resched() provide RCU quiescent state
sched: Make resched_cpu() unconditional
irq_work: Map irq_work_on_queue() to irq_work_on() in !SMP
rcu: Create call_rcu_tasks() kthread at boot time
rcu: Fix up pending cbs check in rcu_prepare_for_idle
memory-barriers: Rework multicopy-atomicity section
memory-barriers: Replace uses of "transitive"
...
Make wait_on_atomic_t() pass the TASK_* mode onto its action function as an
extra argument and make it 'unsigned int throughout.
Also, consolidate a bunch of identical action functions into a default
function that can do the appropriate thing for the mode.
Also, change the argument name in the bit_wait*() function declarations to
reflect the fact that it's the mode and not the bit number.
[Peter Z gives this a grudging ACK, but thinks that the whole atomic_t wait
should be done differently, though he's not immediately sure as to how]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
cc: Ingo Molnar <mingo@kernel.org>
* pm-cpufreq-sched:
cpufreq: schedutil: Reset cached_raw_freq when not in sync with next_freq
* pm-opp:
PM / OPP: Add dev_pm_opp_{un}register_get_pstate_helper()
PM / OPP: Support updating performance state of device's power domain
PM / OPP: add missing of_node_put() for of_get_cpu_node()
PM / OPP: Rename dev_pm_opp_register_put_opp_helper()
PM / OPP: Add missing of_node_put(np)
PM / OPP: Move error message to debug level
PM / OPP: Use snprintf() to avoid kasprintf() and kfree()
PM / OPP: Move the OPP directory out of power/
When the kernel is compiled with !CONFIG_SCHED_DEBUG support, we expect that
all SCHED_FEAT are turned into compile time constants being propagated
to support compiler optimizations.
Specifically, we expect that code blocks like this:
if (sched_feat(FEATURE_NAME) [&& <other_conditions>]) {
/* FEATURE CODE */
}
are turned into dead-code in case FEATURE_NAME defaults to FALSE, and thus
being removed by the compiler from the finale image.
For this mechanism to properly work it's required for the compiler to
have full access, from each translation unit, to whatever is the value
defined by the sched_feat macro. This macro is defined as:
#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
and thus, the compiler can optimize that code only if the value of
sysctl_sched_features is visible within each translation unit.
Since:
029632fbb ("sched: Make separate sched*.c translation units")
the scheduler code has been split into separate translation units
however the definition of sysctl_sched_features is part of
kernel/sched/core.c while, for all the other scheduler modules, it is
visible only via kernel/sched/sched.h as an:
extern const_debug unsigned int sysctl_sched_features
Unfortunately, an extern reference does not allow the compiler to apply
constants propagation. Thus, on !CONFIG_SCHED_DEBUG kernel we still end up
with code to load a memory reference and (eventually) doing an unconditional
jump of a chunk of code.
This mechanism is unavoidable when sched_features can be turned on and off at
run-time. However, this is not the case for "production" kernels compiled with
!CONFIG_SCHED_DEBUG. In this case, sysctl_sched_features is just a constant value
which cannot be changed at run-time and thus memory loads and jumps can be
avoided altogether.
This patch fixes the case of !CONFIG_SCHED_DEBUG kernel by declaring a local version
of the sysctl_sched_features constant for each translation unit. This will
ultimately allow the compiler to perform constants propagation and dead-code
pruning.
Tests have been done, with !CONFIG_SCHED_DEBUG on a v4.14-rc8 with and without
the patch, by running 30 iterations of:
perf bench sched messaging --pipe --thread --group 4 --loop 50000
on a 40 cores Intel(R) Xeon(R) CPU E5-2690 v2 @ 3.00GHz using the
powersave governor to rule out variations due to frequency scaling.
Statistics on the reported completion time:
count mean std min 99% max
v4.14-rc8 30.0 15.7831 0.176032 15.442 16.01226 16.014
v4.14-rc8+patch 30.0 15.5033 0.189681 15.232 15.93938 15.962
... show a 1.8% speedup on average completion time and 0.5% speedup in the
99 percentile.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Brendan Jackman <brendan.jackman@arm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/20171108184101.16006-1-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
'cached_raw_freq' is used to get the next frequency quickly but should
always be in sync with sg_policy->next_freq. There is a case where it is
not and in such cases it should be reset to avoid switching to incorrect
frequencies.
Consider this case for example:
- policy->cur is 1.2 GHz (Max)
- New request comes for 780 MHz and we store that in cached_raw_freq.
- Based on 780 MHz, we calculate the effective frequency as 800 MHz.
- We then see the CPU wasn't idle recently and choose to keep the next
freq as 1.2 GHz.
- Now we have cached_raw_freq is 780 MHz and sg_policy->next_freq is
1.2 GHz.
- Now if the utilization doesn't change in then next request, then the
next target frequency will still be 780 MHz and it will match with
cached_raw_freq. But we will choose 1.2 GHz instead of 800 MHz here.
Fixes: b7eaf1aab9 (cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely)
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.12+ <stable@vger.kernel.org> # 4.12+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Use lockdep to check that IRQs are enabled or disabled as expected. This
way the sanity check only shows overhead when concurrency correctness
debug code is enabled.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David S . Miller <davem@davemloft.net>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/1509980490-4285-12-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After commit 674e75411f (sched: cpufreq: Allow remote cpufreq
callbacks) we stopped to always read the utilization for the CPU we
are running the governor on, and instead we read it for the CPU
which we've been told has updated utilization. This is stored in
sugov_cpu->cpu.
The value is set in sugov_register() but we clear it in sugov_start()
which leads to always looking at the utilization of CPU0 instead of
the correct one.
Fix this by consolidating the initialization code into sugov_start().
Fixes: 674e75411f (sched: cpufreq: Allow remote cpufreq callbacks)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Reviewed-by: Patrick Bellasi <patrick.bellasi@arm.com>
Reviewed-by: Brendan Jackman <brendan.jackman@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add flags to control NOHZ and domain isolation from "isolcpus=", in
order to centralize the isolation features to a common interface. Domain
isolation remains the default so not to break the existing isolcpus
boot paramater behaviour.
Further flags in the future may include 0hz (1hz tick offload) and timers,
workqueue, RCU, kthread, watchdog, likely all merged together in a
common flag ("async"?). In any case, this will have to be modifiable by
cpusets.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-12-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We want to centralize the isolation features, to be done by the housekeeping
subsystem and scheduler domain isolation is a significant part of it.
No intended behaviour change, we just reuse the housekeeping cpumask
and core code.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-11-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We want to centralize the isolation management, done by the housekeeping
subsystem. Therefore we need to handle the nohz_full= parameter from
there.
Since nohz_full= so far has involved unbound timers, watchdog, RCU
and tilegx NAPI isolation, we keep that default behaviour.
nohz_full= will be deprecated in the future. We want to control
the isolation features from the isolcpus= parameter.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-10-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Before we implement isolcpus under housekeeping, we need the isolation
features to be more finegrained. For example some people want NOHZ_FULL
without the full scheduler isolation, others want full scheduler
isolation without NOHZ_FULL.
So let's cut all these isolation features piecewise, at the risk of
overcutting it right now. We can still merge some flags later if they
always make sense together.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-9-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Split the housekeeping config from CONFIG_NO_HZ_FULL. This way we finally
separate the isolation code from NOHZ.
Although a dependency to CONFIG_NO_HZ_FULL remains for now, while the
housekeeping code still deals with NOHZ internals.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-8-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fit it into the housekeeping_*() namespace.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-7-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Housekeeping code still depends on the nohz_full static key. Since we want
to decouple housekeeping from NOHZ, let's create a housekeeping specific
static key.
It's mostly relevant for calls to is_housekeeping_cpu() from the scheduler.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-6-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Nobody needs to access this detail. housekeeping_cpumask() already
takes care of it.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-5-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The housekeeping code is currently tied to the NOHZ code. As we are
planning to make housekeeping independent from it, start with moving
the relevant code to its own file.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-2-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The basic cpu stat is currently shown with "cpu." prefix in
cgroup.stat, and the same information is duplicated in cpu.stat when
cpu controller is enabled. This is ugly and not very scalable as we
want to expand the coverage of stat information which is always
available.
This patch makes cgroup core always create "cpu.stat" file and show
the basic cpu stat there and calls the cpu controller to show the
extra stats when enabled. This ensures that the same information
isn't presented in multiple places and makes future expansion of basic
stats easier.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
cpulist_parse() uses nr_cpumask_bits as a limit to parse the
passed buffer from kernel commandline. What nr_cpumask_bits
represents varies depending upon the CONFIG_CPUMASK_OFFSTACK option:
- If CONFIG_CPUMASK_OFFSTACK=n, then nr_cpumask_bits is the same as
NR_CPUS, which might not represent the # of CPUs that really exist
(default 64). So, there's a chance of a gap between nr_cpu_ids
and NR_CPUS, which ultimately lead towards invalid cpulist_parse()
operation. For example, if isolcpus=9 is passed on an 8 cpu
system (CONFIG_CPUMASK_OFFSTACK=n) it doesn't show the error
that it's supposed to.
This patch fixes this bug by finding the last CPU of the passed
isolcpus= list and checking it against nr_cpu_ids.
It also fixes the error message where the nr_cpu_ids should be
nr_cpu_ids-1, since CPU numbering starts from 0.
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adobriyan@gmail.com
Cc: akpm@linux-foundation.org
Cc: longman@redhat.com
Cc: mka@chromium.org
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/20171023130154.9050-1-rakib.mullick@gmail.com
[ Enhanced the changelog and the kernel message. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
include/linux/cpumask.h | 16 ++++++++++++++++
kernel/sched/topology.c | 4 ++--
2 files changed, 18 insertions(+), 2 deletions(-)
This introduces a "register private expedited" membarrier command which
allows eventual removal of important memory barrier constraints on the
scheduler fast-paths. It changes how the "private expedited" membarrier
command (new to 4.14) is used from user-space.
This new command allows processes to register their intent to use the
private expedited command. This affects how the expedited private
command introduced in 4.14-rc is meant to be used, and should be merged
before 4.14 final.
Processes are now required to register before using
MEMBARRIER_CMD_PRIVATE_EXPEDITED, otherwise that command returns EPERM.
This fixes a problem that arose when designing requested extensions to
sys_membarrier() to allow JITs to efficiently flush old code from
instruction caches. Several potential algorithms are much less painful
if the user register intent to use this functionality early on, for
example, before the process spawns the second thread. Registering at
this time removes the need to interrupt each and every thread in that
process at the first expedited sys_membarrier() system call.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When a CPU lowers its priority (schedules out a high priority task for a
lower priority one), a check is made to see if any other CPU has overloaded
RT tasks (more than one). It checks the rto_mask to determine this and if so
it will request to pull one of those tasks to itself if the non running RT
task is of higher priority than the new priority of the next task to run on
the current CPU.
When we deal with large number of CPUs, the original pull logic suffered
from large lock contention on a single CPU run queue, which caused a huge
latency across all CPUs. This was caused by only having one CPU having
overloaded RT tasks and a bunch of other CPUs lowering their priority. To
solve this issue, commit:
b6366f048e ("sched/rt: Use IPI to trigger RT task push migration instead of pulling")
changed the way to request a pull. Instead of grabbing the lock of the
overloaded CPU's runqueue, it simply sent an IPI to that CPU to do the work.
Although the IPI logic worked very well in removing the large latency build
up, it still could suffer from a large number of IPIs being sent to a single
CPU. On a 80 CPU box, I measured over 200us of processing IPIs. Worse yet,
when I tested this on a 120 CPU box, with a stress test that had lots of
RT tasks scheduling on all CPUs, it actually triggered the hard lockup
detector! One CPU had so many IPIs sent to it, and due to the restart
mechanism that is triggered when the source run queue has a priority status
change, the CPU spent minutes! processing the IPIs.
Thinking about this further, I realized there's no reason for each run queue
to send its own IPI. As all CPUs with overloaded tasks must be scanned
regardless if there's one or many CPUs lowering their priority, because
there's no current way to find the CPU with the highest priority task that
can schedule to one of these CPUs, there really only needs to be one IPI
being sent around at a time.
This greatly simplifies the code!
The new approach is to have each root domain have its own irq work, as the
rto_mask is per root domain. The root domain has the following fields
attached to it:
rto_push_work - the irq work to process each CPU set in rto_mask
rto_lock - the lock to protect some of the other rto fields
rto_loop_start - an atomic that keeps contention down on rto_lock
the first CPU scheduling in a lower priority task
is the one to kick off the process.
rto_loop_next - an atomic that gets incremented for each CPU that
schedules in a lower priority task.
rto_loop - a variable protected by rto_lock that is used to
compare against rto_loop_next
rto_cpu - The cpu to send the next IPI to, also protected by
the rto_lock.
When a CPU schedules in a lower priority task and wants to make sure
overloaded CPUs know about it. It increments the rto_loop_next. Then it
atomically sets rto_loop_start with a cmpxchg. If the old value is not "0",
then it is done, as another CPU is kicking off the IPI loop. If the old
value is "0", then it will take the rto_lock to synchronize with a possible
IPI being sent around to the overloaded CPUs.
If rto_cpu is greater than or equal to nr_cpu_ids, then there's either no
IPI being sent around, or one is about to finish. Then rto_cpu is set to the
first CPU in rto_mask and an IPI is sent to that CPU. If there's no CPUs set
in rto_mask, then there's nothing to be done.
When the CPU receives the IPI, it will first try to push any RT tasks that is
queued on the CPU but can't run because a higher priority RT task is
currently running on that CPU.
Then it takes the rto_lock and looks for the next CPU in the rto_mask. If it
finds one, it simply sends an IPI to that CPU and the process continues.
If there's no more CPUs in the rto_mask, then rto_loop is compared with
rto_loop_next. If they match, everything is done and the process is over. If
they do not match, then a CPU scheduled in a lower priority task as the IPI
was being passed around, and the process needs to start again. The first CPU
in rto_mask is sent the IPI.
This change removes this duplication of work in the IPI logic, and greatly
lowers the latency caused by the IPIs. This removed the lockup happening on
the 120 CPU machine. It also simplifies the code tremendously. What else
could anyone ask for?
Thanks to Peter Zijlstra for simplifying the rto_loop_start atomic logic and
supplying me with the rto_start_trylock() and rto_start_unlock() helper
functions.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170424114732.1aac6dc4@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
find_idlest_group() returns NULL when the local group is idlest. The
caller then continues the find_idlest_group() search at a lower level
of the current CPU's sched_domain hierarchy. find_idlest_group_cpu() is
not consulted and, crucially, @new_cpu is not updated. This means the
search is pointless and we return @prev_cpu from select_task_rq_fair().
This is fixed by initialising @new_cpu to @cpu instead of @prev_cpu.
Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171005114516.18617-6-brendan.jackman@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When 'p' is not allowed on any of the CPUs in the sched_domain, we
currently return NULL from find_idlest_group(), and pointlessly
continue the search on lower sched_domain levels (where 'p' is also not
allowed) before returning prev_cpu regardless (as we have not updated
new_cpu).
Add an explicit check for this case, and add a comment to
find_idlest_group(). Now when find_idlest_group() returns NULL, it always
means that the local group is allowed and idlest.
Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171005114516.18617-5-brendan.jackman@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the local group is not allowed we do not modify this_*_load from
their initial value of 0. That means that the load checks at the end
of find_idlest_group cause us to incorrectly return NULL. Fixing the
initial values to ULONG_MAX means we will instead return the idlest
remote group in that case.
Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171005114516.18617-4-brendan.jackman@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since commit:
83a0a96a5f ("sched/fair: Leverage the idle state info when choosing the "idlest" cpu")
find_idlest_group_cpu() (formerly find_idlest_cpu) no longer returns -1,
so we can simplify the checking of the return value in find_idlest_cpu().
Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171005114516.18617-3-brendan.jackman@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation for changes that would otherwise require adding a new
level of indentation to the while(sd) loop, create a new function
find_idlest_cpu() which contains this loop, and rename the existing
find_idlest_cpu() to find_idlest_group_cpu().
Code inside the while(sd) loop is unchanged. @new_cpu is added as a
variable in the new function, with the same initial value as the
@new_cpu in select_task_rq_fair().
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171005114516.18617-2-brendan.jackman@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The "goto force_balance" here is intended to mitigate the fact that
avg_load calculations can result in bad placement decisions when
priority is asymmetrical.
The original commit that adds it:
fab476228b ("sched: Force balancing on newidle balance if local group has capacity")
explains:
Under certain situations, such as a niced down task (i.e. nice =
-15) in the presence of nr_cpus NICE0 tasks, the niced task lands
on a sched group and kicks away other tasks because of its large
weight. This leads to sub-optimal utilization of the
machine. Even though the sched group has capacity, it does not
pull tasks because sds.this_load >> sds.max_load, and f_b_g()
returns NULL.
A similar but inverted issue also affects ARM big.LITTLE (asymmetrical CPU
capacity) systems - consider 8 always-running, same-priority tasks on a
system with 4 "big" and 4 "little" CPUs. Suppose that 5 of them end up on
the "big" CPUs (which will be represented by one sched_group in the DIE
sched_domain) and 3 on the "little" (the other sched_group in DIE), leaving
one CPU unused. Because the "big" group has a higher group_capacity its
avg_load may not present an imbalance that would cause migrating a
task to the idle "little".
The force_balance case here solves the problem but currently only for
CPU_NEWLY_IDLE balances, which in theory might never happen on the
unused CPU. Including CPU_IDLE in the force_balance case means
there's an upper bound on the time before we can attempt to solve the
underutilization: after DIE's sd->balance_interval has passed the
next nohz balance kick will help us out.
Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170807163900.25180-1-brendan.jackman@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
