In the process of merging kdb to the mainline, the kdb lsmod command
stopped printing the base load address of kernel modules. This is
needed for using kdb in conjunction with external tools such as gdb.
Simply restore the functionality by adding a kdb_printf for the base
load address of the kernel modules.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
The gdbserial protocol handler should return an empty packet instead
of an error string when ever it responds to a command it does not
implement.
The problem cases come from a debugger client sending
qTBuffer, qTStatus, qSearch, qSupported.
The incorrect response from the gdbstub leads the debugger clients to
not function correctly. Recent versions of gdb will not detach correctly as a result of this behavior.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
Without this patch the "ll" linked-list traversal command won't
terminate when you hit q/Q.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
The sched_child_runs_first value in /proc/sched_debug is
currently displayed using a macro meant to split ns time values.
This patch uses the correct macro to display it as a plain
decimal value.
Signed-off-by: Josh Hunt <johunt@akamai.com>
Cc: peterz@infradead.org
Cc: juhlenko@akamai.com
Cc: efault@gmx.de
LKML-Reference: <1279567876-25418-1-git-send-email-johunt@akamai.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Documentation/trace/ftrace.txt says
buffer_size_kb:
This sets or displays the number of kilobytes each CPU
buffer can hold. The tracer buffers are the same size
for each CPU. The displayed number is the size of the
CPU buffer and not total size of all buffers. The
trace buffers are allocated in pages (blocks of memory
that the kernel uses for allocation, usually 4 KB in size).
If the last page allocated has room for more bytes
than requested, the rest of the page will be used,
making the actual allocation bigger than requested.
( Note, the size may not be a multiple of the page size
due to buffer management overhead. )
This can only be updated when the current_tracer
is set to "nop".
But it's incorrect. currently total memory consumption is
'buffer_size_kb x CPUs x 2'.
Why two times difference is there? because ftrace implicitly allocate
the buffer for max latency too.
That makes sad result when admin want to use large buffer. (If admin
want full logging and makes detail analysis). example, If admin
have 24 CPUs machine and write 200MB to buffer_size_kb, the system
consume ~10GB memory (200MB x 24 x 2). umm.. 5GB memory waste is
usually unacceptable.
Fortunatelly, almost all users don't use max latency feature.
The max latency buffer can be disabled easily.
This patch shrink buffer size of the max latency buffer if
unnecessary.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
LKML-Reference: <20100701104554.DA2D.A69D9226@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
__print_flags() and __print_symbolic() use percpu trace_seq:
1) Its memory is allocated at compile time, it wastes memory if we don't use tracing.
2) It is percpu data and it wastes more memory for multi-cpus system.
3) It disables preemption when it executes its core routine
"trace_seq_printf(s, "%s: ", #call);" and introduces latency.
So we move this trace_seq to struct trace_iterator.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4C078350.7090106@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Reorder structure to remove 8 bytes of padding on 64 bit builds.
This shrinks the size to 128 bytes so allowing allocation from a smaller
slab & needed one fewer cache lines.
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
LKML-Reference: <1269516456.2054.8.camel@localhost>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
We found that even enabling a single trace event that will rarely be
triggered can add big overhead to context switch.
(lmbench context switch test)
-------------------------------------------------
2p/0K 2p/16K 2p/64K 8p/16K 8p/64K 16p/16K 16p/64K
ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw
------ ------ ------ ------ ------ ------- -------
2.19 2.3 2.21 2.56 2.13 2.54 2.07
2.39 2.51 2.35 2.75 2.27 2.81 2.24
The overhead is 6% ~ 11%.
It's because when a trace event is enabled 3 tracepoints (sched_switch,
sched_wakeup, sched_wakeup_new) will be activated to map pid to cmdname.
We'd like to avoid this overhead, so add a trace option '(no)record-cmd'
to allow to disable cmdline recording.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4C2D57F4.2050204@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Convert a few calls from kfree_skb to consume_skb
Noticed while I was working on dropwatch that I was detecting lots of internal
skb drops in several places. While some are legitimate, several were not,
freeing skbs that were at the end of their life, rather than being discarded due
to an error. This patch converts those calls sites from using kfree_skb to
consume_skb, which quiets the in-kernel drop_monitor code from detecting them as
drops. Tested successfully by myself
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
All cpumasks are assumed to have cpu 0 permanently set on UP, so it
can't be used to signify whether there's something to be done for the
CPU. workqueue was using cpumask to track which CPU requested rescuer
assistance and this led rescuer thread to think there always are
pending mayday requests on UP, which resulted in infinite busy loops.
This patch fixes the problem by introducing mayday_mask_t and
associated helpers which wrap cpumask on SMP and emulates its behavior
using bitops and unsigned long on UP.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
The default for llseek will change to no_llseek,
so the tracing debugfs files need to add explicit
.llseek assignments. Since we're dealing with regular
files from a VFS perspective, use generic_file_llseek.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: John Kacur <jkacur@redhat.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <1278538820-1392-10-git-send-email-arnd@arndb.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Special traces type was only used by sysprof. Lets remove it now
that sysprof ftrace plugin has been dropped.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Soeren Sandmann <sandmann@daimi.au.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
The sysprof ftrace plugin doesn't seem to be seriously used
somewhere. There is a branch in the sysprof tree that makes
an interface to it, but the real sysprof tool uses either its
own module or perf events.
Drop the sysprof ftrace plugin then, as it's mostly useless.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Soeren Sandmann <sandmann@daimi.au.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Commit f3421797 (workqueue: implement unbound workqueue) incorrectly
tested CONFIG_SMP as part of a C expression in alloc/free_cwqs(). As
CONFIG_SMP is not defined in UP, this breaks build. Fix it by using
Found during linux-next build test.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
With commits 08677214 and 59be5a8e, alloc_bootmem()/free_bootmem() and
friends use the early_res functions for memory management when
NO_BOOTMEM is enabled. This patch adds the kmemleak calls in the
corresponding code paths for bootmem allocations.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: stable@kernel.org
pavel@suse.cz no longer works, replace it with working address.
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Added sysfs primitives to padata subsystem. Now API user may
embedded kobject each padata instance contains into any sysfs
hierarchy. For now padata sysfs interface provides only
two objects:
serial_cpumask [RW] - cpumask for serial workers
parallel_cpumask [RW] - cpumask for parallel workers
Signed-off-by: Dan Kruchinin <dkruchinin@acm.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The aim of this patch is to make two separate cpumasks
for padata parallel and serial workers respectively.
It allows user to make more thin and sophisticated configurations
of padata framework. For example user may bind parallel and serial workers to non-intersecting
CPU groups to gain better performance. Also each padata instance has notifiers chain for its
cpumasks now. If either parallel or serial or both masks were changed all
interested subsystems will get notification about that. It's especially useful
if padata user uses algorithm for callback CPU selection according to serial cpumask.
Signed-off-by: Dan Kruchinin <dkruchinin@acm.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The ACPI suspend code calls suspend_nvs_free() at a wrong place,
which may lead to a memory leak if there's an error executing
acpi_pm_prepare(), because acpi_pm_finish() will not be called in
that case. However, the root cause of this problem is the
apparently confusing ordering of calls in suspend error paths that
needs to be fixed.
In addition to that, fix a typo in a label name in suspend.c.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Len Brown <len.brown@intel.com>
There is an inconsistency between hibernation_platform_enter()
and hibernation_snapshot(), because the latter calls
hibernation_ops->end() after failing hibernation_ops->begin(), while
the former doesn't do that. Make hibernation_snapshot() behave in
the same way as hibernation_platform_enter() in that respect.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Len Brown <len.brown@intel.com>
The hibernation_platform_enter() function calls dpm_suspend_noirq()
instead of dpm_resume_noirq() by mistake. Fix this.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Len Brown <len.brown@intel.com>
All current users of pm_qos_add_request() have the ability to supply
the memory required by the pm_qos routines, so make them do this and
eliminate the kmalloc() with pm_qos_add_request(). This has the
double benefit of making the call never fail and allowing it to be
called from atomic context.
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: mark gross <markgross@thegnar.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
A lot of the pm_qos extremal value handling is really duplicating what a
priority ordered list does, just in a less efficient fashion. Simply
redoing the implementation in terms of a plist gets rid of a lot of this
junk (although there are several other strange things that could do with
tidying up, like pm_qos_request_list has to carry the pm_qos_class with
every node, simply because it doesn't get passed in to
pm_qos_update_request even though every caller knows full well what
parameter it's updating).
I think this redo is a win independent of android, so we should do
something like this now.
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: mark gross <markgross@thegnar.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
One of the arguments during the suspend blockers discussion was that
the mainline kernel didn't contain any mechanisms making it possible
to avoid races between wakeup and system suspend.
Generally, there are two problems in that area. First, if a wakeup
event occurs exactly when /sys/power/state is being written to, it
may be delivered to user space right before the freezer kicks in, so
the user space consumer of the event may not be able to process it
before the system is suspended. Second, if a wakeup event occurs
after user space has been frozen, it is not generally guaranteed that
the ongoing transition of the system into a sleep state will be
aborted.
To address these issues introduce a new global sysfs attribute,
/sys/power/wakeup_count, associated with a running counter of wakeup
events and three helper functions, pm_stay_awake(), pm_relax(), and
pm_wakeup_event(), that may be used by kernel subsystems to control
the behavior of this attribute and to request the PM core to abort
system transitions into a sleep state already in progress.
The /sys/power/wakeup_count file may be read from or written to by
user space. Reads will always succeed (unless interrupted by a
signal) and return the current value of the wakeup events counter.
Writes, however, will only succeed if the written number is equal to
the current value of the wakeup events counter. If a write is
successful, it will cause the kernel to save the current value of the
wakeup events counter and to abort the subsequent system transition
into a sleep state if any wakeup events are reported after the write
has returned.
[The assumption is that before writing to /sys/power/state user space
will first read from /sys/power/wakeup_count. Next, user space
consumers of wakeup events will have a chance to acknowledge or
veto the upcoming system transition to a sleep state. Finally, if
the transition is allowed to proceed, /sys/power/wakeup_count will
be written to and if that succeeds, /sys/power/state will be written
to as well. Still, if any wakeup events are reported to the PM core
by kernel subsystems after that point, the transition will be
aborted.]
Additionally, put a wakeup events counter into struct dev_pm_info and
make these per-device wakeup event counters available via sysfs,
so that it's possible to check the activity of various wakeup event
sources within the kernel.
To illustrate how subsystems can use pm_wakeup_event(), make the
low-level PCI runtime PM wakeup-handling code use it.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: markgross <markgross@thegnar.org>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
There are a few typos in kernel/power/swap.c. Fix them.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
As of commit dcce284 ("mm: Extend gfp masking to the page
allocator") and commit 7e85ee0 ("slab,slub: don't enable
interrupts during early boot"), the slab allocator makes
sure we don't attempt to sleep during boot.
Therefore, remove bootmem special cases from the scheduler
and use plain GFP_KERNEL instead.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1279225102-2572-1-git-send-email-penberg@cs.helsinki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Norbert reported that nohz_ratelimit() causes his laptop to burn about
4W (40%) extra. For now back out the change and see if we can adjust
the power management code to make better decisions.
Reported-by: Norbert Preining <preining@logic.at>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Mike Galbraith <efault@gmx.de>
Cc: Arjan van de Ven <arjan@infradead.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Currently we update cpu_power() too often, update_group_power() only
updates the local group's cpu_power but it gets called for all groups.
Furthermore, CPU_NEWLY_IDLE invocations will result in all cpus
calling it, even though a slow update of cpu_power is sufficient.
Therefore move the update under 'idle != CPU_NEWLY_IDLE &&
local_group' to reduce superfluous invocations.
Reported-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1278612989.1900.176.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Suresh spotted that we don't update the rq->clock in the nohz
load-balancer path.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1278626014.2834.74.camel@sbs-t61.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The ksym (breakpoint) ftrace plugin has been superseded by perf
tools that are much more poweful to use the cpu breakpoints.
This tracer doesn't bring more feature. It has been deprecated
for a while now, lets remove it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
We count the number of processed objects on a percpu basis,
so we need to go through all the percpu reorder queues to calculate
the sequence number of the next object that needs serialization.
This patch changes this to count the number of processed objects
global. So we can calculate the sequence number and the percpu
reorder queue of the next object that needs serialization without
searching through the percpu reorder queues. This avoids some
accesses to memory of foreign cpus.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
To return -EINPROGRESS on success in padata_do_parallel was
considered to be odd. This patch changes this to return zero
on success. Also the only user of padata, pcrypt is adapted to
convert a return of zero to -EINPROGRESS within the crypto layer.
This also removes the pcrypt fallback if padata_do_parallel
was called on a not running padata instance as we can't handle it
anymore. This fallback was unused, so it's save to remove it.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch fixes a bug when the padata cpumask does not
intersect with the active cpumask. In this case we get a
division by zero in padata_alloc_pd and we end up with a
useless padata instance. Padata can end up with an empty
cpumask for two reasons:
1. A user removed the last cpu that belongs to the padata
cpumask and the active cpumask.
2. The last cpu that belongs to the padata cpumask and the
active cpumask goes offline.
We introduce a function padata_validate_cpumask to check if the padata
cpumask does intersect with the active cpumask. If the cpumasks do not
intersect we mark the instance as invalid, so it can't be used. We do not
allocate the cpumask dependend recources in this case. This fixes the
division by zero and keeps the padate instance in a consistent state.
It's not possible to trigger this bug by now because the only padata user,
pcrypt uses always the possible cpumask.
Reported-by: Dan Kruchinin <dkruchinin@acm.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch makes padata_stop to block until the padata
instance is unused. Also we split padata_stop to a locked
and a unlocked version. This is in preparation to be able
to change the cpumask after a call to patata stop.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch introduces the PADATA_INVALID flag which is
checked on padata start. This will be used to mark a padata
instance as invalid, if the padata cpumask does not intersect
with the active cpumask. we change padata_start to return an
error if the PADATA_INVALID is set. Also we adapt the only
padata user, pcrypt to this change.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
maybe_create_worker() mismanaged locking when worker creation fails
and it has to retry. Fix locking and simplify lock manipulation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Yong Zhang <yong.zhang@windriver.com>
I have shown by code review that no driver takes
the BKL at init time any more, so whatever the
init code was locking against is no longer there
and it is now safe to remove the BKL there.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Steven Rostedt <rostedt@goodmis>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Variable on the stack is not initialized to zero, do it
explicitly.
This bug was found by a compiler warning:
kernel/watchdog.c:463: warning: 'result' may be used uninitialized in this function
Signed-off-by: Kulikov Vasiliy <segooon@gmail.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1278316854-28442-1-git-send-email-segooon@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Support string type tracing and printing in kprobe-tracer.
This allows user to trace string data in kernel including __user data. Note
that sometimes __user data may not be accessed if it is paged-out (sorry, but
kprobes operation should be done in atomic, we can not wait for page-in).
Commiter note: Fixed up conflicts with b7e2ece.
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100519195724.2885.18788.stgit@localhost6.localdomain6>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
We should initialize the module dynamic debug datastructures
only after determining that the module is not loaded yet. This
fixes a bug that introduced in 2.6.35-rc2, where when a trying
to load a module twice, we also load it's dynamic printing data
twice which causes all sorts of nasty issues. Also handle
the dynamic debug cleanup later on failure.
Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed a #ifdef)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
WQ_SINGLE_CPU combined with @max_active of 1 is used to achieve full
ordering among works queued to a workqueue. The same can be achieved
using WQ_UNBOUND as unbound workqueues always use the gcwq for
WORK_CPU_UNBOUND. As @max_active is always one and benefits from cpu
locality isn't accessible anyway, serving them with unbound workqueues
should be fine.
Drop WQ_SINGLE_CPU support and use WQ_UNBOUND instead. Note that most
single thread workqueue users will be converted to use multithread or
non-reentrant instead and only the ones which require strict ordering
will keep using WQ_UNBOUND + @max_active of 1.
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch implements unbound workqueue which can be specified with
WQ_UNBOUND flag on creation. An unbound workqueue has the following
properties.
* It uses a dedicated gcwq with a pseudo CPU number WORK_CPU_UNBOUND.
This gcwq is always online and disassociated.
* Workers are not bound to any CPU and not concurrency managed. Works
are dispatched to workers as soon as possible and the only applied
limitation is @max_active. IOW, all unbound workqeueues are
implicitly high priority.
Unbound workqueues can be used as simple execution context provider.
Contexts unbound to any cpu are served as soon as possible.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: David Howells <dhowells@redhat.com>
In preparation of WQ_UNBOUND addition, make the following changes.
* Add WORK_CPU_* constants for pseudo cpu id numbers used (currently
only WORK_CPU_NONE) and use them instead of NR_CPUS. This is to
allow another pseudo cpu id for unbound cpu.
* Reorder WQ_* flags.
* Make workqueue_struct->cpu_wq a union which contains a percpu
pointer, regular pointer and an unsigned long value and use
kzalloc/kfree() in UP allocation path. This will be used to
implement unbound workqueues which will use only one cwq on SMPs.
* Move alloc_cwqs() allocation after initialization of wq fields, so
that alloc_cwqs() has access to wq->flags.
* Trivial relocation of wq local variables in freeze functions.
These changes don't cause any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
When there's no pending work to do, worker_thread() goes back to sleep
after waking up without checking whether worker management is
necessary. This means that idle worker exit requests can be ignored
if the gcwq stays empty.
Fix it by making worker_thread() always check whether worker
management is necessary before going to sleep.
Signed-off-by: Tejun Heo <tj@kernel.org>
get_work_gcwq() was incorrectly triggering BUG_ON() if cpu number is
equal to or higher than num_possible_cpus() instead of nr_cpu_ids.
Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
When one flusher is cascading to the next flusher, it first sets
wq->first_flusher to the next one and sets up the next flush cycle.
If there's nothing to do for the next cycle, it clears
wq->flush_flusher and proceeds to the one after that.
If the woken up flusher checks wq->first_flusher before it gets
cleared, it will incorrectly assume the role of the first flusher,
which triggers BUG_ON() sanity check.
Fix it by checking wq->first_flusher again after grabbing the mutex.
Signed-off-by: Tejun Heo <tj@kernel.org>
worker_set/clr_flags() assume that if none of NOT_RUNNING flags is set
the worker must be contributing to nr_running which is only true if
the worker is actually running.
As when called from self, it is guaranteed that the worker is running,
those functions can be safely used from the worker itself and they
aren't necessary from other places anyway. Make the following changes
to fix the bug.
* Make worker_set/clr_flags() whine if not called from self.
* Convert all places which called those functions from other tasks to
manipulate flags directly.
* Make trustee_thread() directly clear nr_running after setting
WORKER_ROGUE on all workers. This is the only place where
nr_running manipulation is necessary outside of workers themselves.
* While at it, add sanity check for nr_running in worker_enter_idle().
Signed-off-by: Tejun Heo <tj@kernel.org>
Commit 0224cf4c5e (sched: Intoduce get_cpu_iowait_time_us())
broke things by not making sure preemption was indeed disabled
by the callers of nr_iowait_cpu() which took the iowait value of
the current cpu.
This resulted in a heap of preempt warnings. Cure this by making
nr_iowait_cpu() take a cpu number and fix up the callers to pass
in the right number.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-pm@lists.linux-foundation.org
LKML-Reference: <1277968037.1868.120.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Conflicts:
fs/fs-writeback.c
Merge reason: Resolve the conflict
Note, i picked the version from Linus's tree, which effectively reverts
the fs-writeback.c bits of:
b97181f: fs: remove all rcu head initializations, except on_stack initializations
As the upstream changes to this file changed this code heavily and the
first attempt to resolve the conflict resulted in a non-booting kernel.
It's safer to re-try this portion of the commit cleanly.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
futex_find_get_task is currently used (through lookup_pi_state) from two
contexts, futex_requeue and futex_lock_pi_atomic. None of the paths
looks it needs the credentials check, though. Different (e)uids
shouldn't matter at all because the only thing that is important for
shared futex is the accessibility of the shared memory.
The credentail check results in glibc assert failure or process hang (if
glibc is compiled without assert support) for shared robust pthread
mutex with priority inheritance if a process tries to lock already held
lock owned by a process with a different euid:
pthread_mutex_lock.c:312: __pthread_mutex_lock_full: Assertion `(-(e)) != 3 || !robust' failed.
The problem is that futex_lock_pi_atomic which is called when we try to
lock already held lock checks the current holder (tid is stored in the
futex value) to get the PI state. It uses lookup_pi_state which in turn
gets task struct from futex_find_get_task. ESRCH is returned either
when the task is not found or if credentials check fails.
futex_lock_pi_atomic simply returns if it gets ESRCH. glibc code,
however, doesn't expect that robust lock returns with ESRCH because it
should get either success or owner died.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Darren Hart <dvhltc@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When crashkernel is not enabled, "echo 0 > /sys/kernel/kexec_crash_size"
OOPSes the kernel in crash_shrink_memory. This happens when
crash_shrink_memory tries to release the 'crashk_res' resource which are
not reserved. Also value of "/sys/kernel/kexec_crash_size" shows as 1,
which should be 0.
This patch fixes the OOPS in crash_shrink_memory and shows
"/sys/kernel/kexec_crash_size" as 0 when crash kernel memory is not
reserved.
Signed-off-by: Pavan Naregundi <pavan@linux.vnet.ibm.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Simon Horman <horms@verge.net.au>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No logic changes, only spelling.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: linuxppc-dev@ozlabs.org
Cc: David Howells <dhowells@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <15249.1277776921@neuling.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch implements cpu intensive workqueue which can be specified
with WQ_CPU_INTENSIVE flag on creation. Works queued to a cpu
intensive workqueue don't participate in concurrency management. IOW,
it doesn't contribute to gcwq->nr_running and thus doesn't delay
excution of other works.
Note that although cpu intensive works won't delay other works, they
can be delayed by other works. Combine with WQ_HIGHPRI to avoid being
delayed by other works too.
As the name suggests this is useful when using workqueue for cpu
intensive works. Workers executing cpu intensive works are not
considered for workqueue concurrency management and left for the
scheduler to manage.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
This patch implements high priority workqueue which can be specified
with WQ_HIGHPRI flag on creation. A high priority workqueue has the
following properties.
* A work queued to it is queued at the head of the worklist of the
respective gcwq after other highpri works, while normal works are
always appended at the end.
* As long as there are highpri works on gcwq->worklist,
[__]need_more_worker() remains %true and process_one_work() wakes up
another worker before it start executing a work.
The above two properties guarantee that works queued to high priority
workqueues are dispatched to workers and start execution as soon as
possible regardless of the state of other works.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Implement the following utility APIs.
workqueue_set_max_active() : adjust max_active of a wq
workqueue_congested() : test whether a wq is contested
work_cpu() : determine the last / current cpu of a work
work_busy() : query whether a work is busy
* Anton Blanchard fixed missing ret initialization in work_busy().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Anton Blanchard <anton@samba.org>
This patch makes changes to make new workqueue features available to
its users.
* Now that workqueue is more featureful, there should be a public
workqueue creation function which takes paramters to control them.
Rename __create_workqueue() to alloc_workqueue() and make 0
max_active mean WQ_DFL_ACTIVE. In the long run, all
create_workqueue_*() will be converted over to alloc_workqueue().
* To further unify access interface, rename keventd_wq to system_wq
and export it.
* Add system_long_wq and system_nrt_wq. The former is to host long
running works separately (so that flush_scheduled_work() dosen't
take so long) and the latter guarantees any queued work item is
never executed in parallel by multiple CPUs. These will be used by
future patches to update workqueue users.
Signed-off-by: Tejun Heo <tj@kernel.org>
Define WQ_MAX_ACTIVE and create keventd with max_active set to half of
it which means that keventd now can process upto WQ_MAX_ACTIVE / 2 - 1
works concurrently. Unless some combination can result in dependency
loop longer than max_active, deadlock won't happen and thus it's
unnecessary to check whether current_is_keventd() before trying to
schedule a work. Kill current_is_keventd().
(Lockdep annotations are broken. We need lock_map_acquire_read_norecurse())
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Instead of creating a worker for each cwq and putting it into the
shared pool, manage per-cpu workers dynamically.
Works aren't supposed to be cpu cycle hogs and maintaining just enough
concurrency to prevent work processing from stalling due to lack of
processing context is optimal. gcwq keeps the number of concurrent
active workers to minimum but no less. As long as there's one or more
running workers on the cpu, no new worker is scheduled so that works
can be processed in batch as much as possible but when the last
running worker blocks, gcwq immediately schedules new worker so that
the cpu doesn't sit idle while there are works to be processed.
gcwq always keeps at least single idle worker around. When a new
worker is necessary and the worker is the last idle one, the worker
assumes the role of "manager" and manages the worker pool -
ie. creates another worker. Forward-progress is guaranteed by having
dedicated rescue workers for workqueues which may be necessary while
creating a new worker. When the manager is having problem creating a
new worker, mayday timer activates and rescue workers are summoned to
the cpu and execute works which might be necessary to create new
workers.
Trustee is expanded to serve the role of manager while a CPU is being
taken down and stays down. As no new works are supposed to be queued
on a dead cpu, it just needs to drain all the existing ones. Trustee
continues to try to create new workers and summon rescuers as long as
there are pending works. If the CPU is brought back up while the
trustee is still trying to drain the gcwq from the previous offlining,
the trustee will kill all idles ones and tell workers which are still
busy to rebind to the cpu, and pass control over to gcwq which assumes
the manager role as necessary.
Concurrency managed worker pool reduces the number of workers
drastically. Only workers which are necessary to keep the processing
going are created and kept. Also, it reduces cache footprint by
avoiding unnecessarily switching contexts between different workers.
Please note that this patch does not increase max_active of any
workqueue. All workqueues can still only process one work per cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement worker_{set|clr}_flags() to manipulate worker flags. These
are currently simple wrappers but logics to track the current worker
state and the current level of concurrency will be added.
Signed-off-by: Tejun Heo <tj@kernel.org>
Use gcwq->worklist instead of cwq->worklist and break the strict
association between a cwq and its worker. All works queued on a cpu
are queued on gcwq->worklist and processed by any available worker on
the gcwq.
As there no longer is strict association between a cwq and its worker,
whether a work is executing can now only be determined by calling
[__]find_worker_executing_work().
After this change, the only association between a cwq and its worker
is that a cwq puts a worker into shared worker pool on creation and
kills it on destruction. As all workqueues are still limited to
max_active of one, this means that there are always at least as many
workers as active works and thus there's no danger for deadlock.
The break of strong association between cwqs and workers requires
somewhat clumsy changes to current_is_keventd() and
destroy_workqueue(). Dynamic worker pool management will remove both
clumsy changes. current_is_keventd() won't be necessary at all as the
only reason it exists is to avoid queueing a work from a work which
will be allowed just fine. The clumsy part of destroy_workqueue() is
added because a worker can only be destroyed while idle and there's no
guarantee a worker is idle when its wq is going down. With dynamic
pool management, workers are not associated with workqueues at all and
only idle ones will be submitted to destroy_workqueue() so the code
won't be necessary anymore.
Signed-off-by: Tejun Heo <tj@kernel.org>
With gcwq managing all the workers and work->data pointing to the last
gcwq it was on, non-reentrance can be easily implemented by checking
whether the work is still running on the previous gcwq on queueing.
Implement it.
Signed-off-by: Tejun Heo <tj@kernel.org>
To implement non-reentrant workqueue, the last gcwq a work was
executed on must be reliably obtainable as long as the work structure
is valid even if the previous workqueue has been destroyed.
To achieve this, work->data will be overloaded to carry the last cpu
number once execution starts so that the previous gcwq can be located
reliably. This means that cwq can't be obtained from work after
execution starts but only gcwq.
Implement set_work_{cwq|cpu}(), get_work_[g]cwq() and
clear_work_data() to set work data to the cpu number when starting
execution, access the overloaded work data and clear it after
cancellation.
queue_delayed_work_on() is updated to preserve the last cpu while
in-flight in timer and other callers which depended on getting cwq
from work after execution starts are converted to depend on gcwq
instead.
* Anton Blanchard fixed compile error on powerpc due to missing
linux/threads.h include.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Anton Blanchard <anton@samba.org>
Now that all the workers are tracked by gcwq, we can find which worker
is executing a work from gcwq. Implement find_worker_executing_work()
and make worker track its current_cwq so that we can find things the
other way around. This will be used to implement non-reentrant wqs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reimplement st (single thread) workqueue so that it's friendly to
shared worker pool. It was originally implemented by confining st
workqueues to use cwq of a fixed cpu and always having a worker for
the cpu. This implementation isn't very friendly to shared worker
pool and suboptimal in that it ends up crossing cpu boundaries often.
Reimplement st workqueue using dynamic single cpu binding and
cwq->limit. WQ_SINGLE_THREAD is replaced with WQ_SINGLE_CPU. In a
single cpu workqueue, at most single cwq is bound to the wq at any
given time. Arbitration is done using atomic accesses to
wq->single_cpu when queueing a work. Once bound, the binding stays
till the workqueue is drained.
Note that the binding is never broken while a workqueue is frozen.
This is because idle cwqs may have works waiting in delayed_works
queue while frozen. On thaw, the cwq is restarted if there are any
delayed works or unbound otherwise.
When combined with max_active limit of 1, single cpu workqueue has
exactly the same execution properties as the original single thread
workqueue while allowing sharing of per-cpu workers.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reimplement CPU hotplugging support using trustee thread. On CPU
down, a trustee thread is created and each step of CPU down is
executed by the trustee and workqueue_cpu_callback() simply drives and
waits for trustee state transitions.
CPU down operation no longer waits for works to be drained but trustee
sticks around till all pending works have been completed. If CPU is
brought back up while works are still draining,
workqueue_cpu_callback() tells trustee to step down and tell workers
to rebind to the cpu.
As it's difficult to tell whether cwqs are empty if it's freezing or
frozen, trustee doesn't consider draining to be complete while a gcwq
is freezing or frozen (tracked by new GCWQ_FREEZING flag). Also,
workers which get unbound from their cpu are marked with WORKER_ROGUE.
Trustee based implementation doesn't bring any new feature at this
point but it will be used to manage worker pool when dynamic shared
worker pool is implemented.
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement worker states. After created, a worker is STARTED. While a
worker isn't processing a work, it's IDLE and chained on
gcwq->idle_list. While processing a work, a worker is BUSY and
chained on gcwq->busy_hash. Also, gcwq now counts the number of all
workers and idle ones.
worker_thread() is restructured to reflect state transitions.
cwq->more_work is removed and waking up a worker makes it check for
events. A worker is killed by setting DIE flag while it's IDLE and
waking it up.
This gives gcwq better visibility of what's going on and allows it to
find out whether a work is executing quickly which is necessary to
have multiple workers processing the same cwq.
Signed-off-by: Tejun Heo <tj@kernel.org>
There is one gcwq (global cwq) per each cpu and all cwqs on an cpu
point to it. A gcwq contains a lock to be used by all cwqs on the cpu
and an ida to give IDs to workers belonging to the cpu.
This patch introduces gcwq, moves worker_ida into gcwq and make all
cwqs on the same cpu use the cpu's gcwq->lock instead of separate
locks. gcwq->ida is now protected by gcwq->lock too.
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, workqueue freezing is implemented by marking the worker
freezeable and calling try_to_freeze() from dispatch loop.
Reimplement it using cwq->limit so that the workqueue is frozen
instead of the worker.
* workqueue_struct->saved_max_active is added which stores the
specified max_active on initialization.
* On freeze, all cwq->max_active's are quenched to zero. Freezing is
complete when nr_active on all cwqs reach zero.
* On thaw, all cwq->max_active's are restored to wq->saved_max_active
and the worklist is repopulated.
This new implementation allows having single shared pool of workers
per cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
Add cwq->nr_active, cwq->max_active and cwq->delayed_work. nr_active
counts the number of active works per cwq. A work is active if it's
flushable (colored) and is on cwq's worklist. If nr_active reaches
max_active, new works are queued on cwq->delayed_work and activated
later as works on the cwq complete and decrement nr_active.
cwq->max_active can be specified via the new @max_active parameter to
__create_workqueue() and is set to 1 for all workqueues for now. As
each cwq has only single worker now, this double queueing doesn't
cause any behavior difference visible to its users.
This will be used to reimplement freeze/thaw and implement shared
worker pool.
Signed-off-by: Tejun Heo <tj@kernel.org>
A work is linked to the next one by having WORK_STRUCT_LINKED bit set
and these links can be chained. When a linked work is dispatched to a
worker, all linked works are dispatched to the worker's newly added
->scheduled queue and processed back-to-back.
Currently, as there's only single worker per cwq, having linked works
doesn't make any visible behavior difference. This change is to
prepare for multiple shared workers per cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
Separate out worker thread related information to struct worker from
struct cpu_workqueue_struct and implement helper functions to deal
with the new struct worker. The only change which is visible outside
is that now workqueue worker are all named "kworker/CPUID:WORKERID"
where WORKERID is allocated from per-cpu ida.
This is in preparation of concurrency managed workqueue where shared
multiple workers would be available per cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reimplement workqueue flushing using color coded works. wq has the
current work color which is painted on the works being issued via
cwqs. Flushing a workqueue is achieved by advancing the current work
colors of cwqs and waiting for all the works which have any of the
previous colors to drain.
Currently there are 16 possible colors, one is reserved for no color
and 15 colors are useable allowing 14 concurrent flushes. When color
space gets full, flush attempts are batched up and processed together
when color frees up, so even with many concurrent flushers, the new
implementation won't build up huge queue of flushers which has to be
processed one after another.
Only works which are queued via __queue_work() are colored. Works
which are directly put on queue using insert_work() use NO_COLOR and
don't participate in workqueue flushing. Currently only works used
for work-specific flush fall in this category.
This new implementation leaves only cleanup_workqueue_thread() as the
user of flush_cpu_workqueue(). Just make its users use
flush_workqueue() and kthread_stop() directly and kill
cleanup_workqueue_thread(). As workqueue flushing doesn't use barrier
request anymore, the comment describing the complex synchronization
around it in cleanup_workqueue_thread() is removed together with the
function.
This new implementation is to allow having and sharing multiple
workers per cpu.
Please note that one more bit is reserved for a future work flag by
this patch. This is to avoid shifting bits and updating comments
later.
Signed-off-by: Tejun Heo <tj@kernel.org>
work->data field is used for two purposes. It points to cwq it's
queued on and the lower bits are used for flags. Currently, two bits
are reserved which is always safe as 4 byte alignment is guaranteed on
every architecture. However, future changes will need more flag bits.
On SMP, the percpu allocator is capable of honoring larger alignment
(there are other users which depend on it) and larger alignment works
just fine. On UP, percpu allocator is a thin wrapper around
kzalloc/kfree() and don't honor alignment request.
This patch introduces WORK_STRUCT_FLAG_BITS and implements
alloc/free_cwqs() which guarantees max(1 << WORK_STRUCT_FLAG_BITS,
__alignof__(unsigned long long) alignment both on SMP and UP. On SMP,
simply wrapping percpu allocator is enough. On UP, extra space is
allocated so that cwq can be aligned and the original pointer can be
stored after it which is used in the free path.
* Alignment problem on UP is reported by Michal Simek.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Reported-by: Michal Simek <michal.simek@petalogix.com>
Worker management is about to be overhauled. Simplify things by
removing cpu_populated_map, creating workers for all possible cpus and
making single threaded workqueues behave more like multi threaded
ones.
After this patch, all cwqs are always initialized, all workqueues are
linked on the workqueues list and workers for all possibles cpus
always exist. This also makes CPU hotplug support simpler - checking
->cpus_allowed before processing works in worker_thread() and flushing
cwqs on CPU_POST_DEAD are enough.
While at it, make get_cwq() always return the cwq for the specified
cpu, add target_cwq() for cases where single thread distinction is
necessary and drop all direct usage of per_cpu_ptr() on wq->cpu_wq.
Signed-off-by: Tejun Heo <tj@kernel.org>
Strip tracing code from workqueue and remove workqueue tracing. This
is temporary measure till concurrency managed workqueue is complete.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Work flags are about to see more traditional mask handling. Define
WORK_STRUCT_*_BIT as the bit position constant and redefine
WORK_STRUCT_* as bit masks. Also, make WORK_STRUCT_STATIC_* flags
conditional
While at it, re-define these constants as enums and use
WORK_STRUCT_STATIC instead of hard-coding 2 in
WORK_DATA_STATIC_INIT().
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, __create_workqueue_key() takes @singlethread and
@freezeable paramters and store them separately in workqueue_struct.
Merge them into a single flags parameter and field and use
WQ_FREEZEABLE and WQ_SINGLE_THREAD.
Signed-off-by: Tejun Heo <tj@kernel.org>
Make the following updates in preparation of concurrency managed
workqueue. None of these changes causes any visible behavior
difference.
* Add comments and adjust indentations to data structures and several
functions.
* Rename wq_per_cpu() to get_cwq() and swap the position of two
parameters for consistency. Convert a direct per_cpu_ptr() access
to wq->cpu_wq to get_cwq().
* Add work_static() and Update set_wq_data() such that it sets the
flags part to WORK_STRUCT_PENDING | WORK_STRUCT_STATIC if static |
@extra_flags.
* Move santiy check on work->entry emptiness from queue_work_on() to
__queue_work() which all queueing paths share.
* Make __queue_work() take @cpu and @wq instead of @cwq.
* Restructure flush_work() and __create_workqueue_key() to make them
easier to modify.
Signed-off-by: Tejun Heo <tj@kernel.org>
With stop_machine() converted to use cpu_stop, RT workqueue doesn't
have any user left. Kill RT workqueue support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement kthread_data() which takes @task pointing to a kthread and
returns @data specified when creating the kthread. The caller is
responsible for ensuring the validity of @task when calling this
function.
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement simple work processor for kthread. This is to ease using
kthread. Single thread workqueue used to be used for things like this
but workqueue won't guarantee fixed kthread association anymore to
enable worker sharing.
This can be used in cases where specific kthread association is
necessary, for example, when it should have RT priority or be assigned
to certain cgroup.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Because kprobes and syscalls need special processing to register
events, the class->reg() method was created to handle the differences.
But instead of creating a default ->reg for perf and ftrace events,
the code was scattered with:
if (class->reg)
class->reg();
else
default_reg();
This is messy and can also lead to bugs.
This patch cleans up this code and creates a default reg() entry for
the events allowing for the code to directly call the class->reg()
without the condition.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The nsecs_str string is a local variable defined as:
char nsecs_str[5];
It is possible for the snprintf call to use a size value larger than the
size of the string. This should not cause a buffer overrun as it is
written now due to the value for the string format "%03lu" can not be
larger than 1000. However, this change makes it correct. By making the
size correct we guard against potential future changes that could actually
cause a buffer overrun.
Signed-off-by: Chase Douglas <chase.douglas@canonical.com>
LKML-Reference: <1276619355-18116-1-git-send-email-chase.douglas@canonical.com>
[ added 'UL' to number 8 to fix gcc warning comparing it to sizeof() ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Let trace_module_add_events() and event_trace_init() call
__trace_add_event_call().
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4BFA37E9.1020106@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
raw_init callback is optional.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4BFA37D4.7070500@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Every event (or event class) has it's define_fields callback,
so the test is redundant.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4BFA37BC.8080707@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Every event has the same common fields, so it's a big waste of
memory to have a copy of those fields for every event.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4BFA3759.30105@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
All syscall exit events have the same fields.
The kernel size drops 2.5K:
text data bss dec hex filename
7018612 2034376 7251132 16304120 f8c7f8 vmlinux.o.orig
7018612 2031888 7251132 16301632 f8be40 vmlinux.o
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4BFA3746.8070100@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
GCC 4.4.1 on ARM has been observed to replace the while loop in
sched_avg_update with a call to uldivmod, resulting in the
following build failure at link-time:
kernel/built-in.o: In function `sched_avg_update':
kernel/sched.c:1261: undefined reference to `__aeabi_uldivmod'
kernel/sched.c:1261: undefined reference to `__aeabi_uldivmod'
make: *** [.tmp_vmlinux1] Error 1
This patch introduces a fake data hazard to the loop body to
prevent the compiler optimising the loop away.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Freeing a perf event can happen in several ways. A task
calls perf_event_exit_task() right before exiting. This helper
will detach all the events from the task context and queue their
removal through free_event() if they are child tasks. The task
also loses its context reference there.
Releasing the breakpoint slot from the constraint table is made
from free_event() that calls release_bp_slot(). We count the number
of breakpoints this task is running by looking at the task's
perf_event_ctxp and iterating through its attached events.
But at this time, the reference to this context has been cleaned up
already.
So looking at the event->ctx instead of task->perf_event_ctxp
to count the remaining breakpoints should solve the problem.
At least it would for child breakpoints, but not for parent ones.
If the parent exits before the child, it will remove all its
events from the context but free_event() will be called later,
on fd release time. And checking the number of breakpoints the
task has attached to its context at this time is unreliable as all
events have been removed from the context.
To solve this, we keep track of the list of per task breakpoints.
On top of it, we maintain our array of numbers of breakpoints used
by the tasks. We use the context address as a task id.
So, instead of looking at the number of events attached to a context,
we walk through our list of per task breakpoints and count the number
of breakpoints that use the same ctx than the one to be reserved or
released from the constraint table, and update the count on top of this
result.
In the meantime it solves a bad refcounting, it also solves a warning,
reported by Paul.
Badness at /home/paulus/kernel/perf/kernel/hw_breakpoint.c:114
NIP: c0000000000cb470 LR: c0000000000cb46c CTR: c00000000032d9b8
REGS: c000000118e7b570 TRAP: 0700 Not tainted (2.6.35-rc3-perf-00008-g76b0f13
)
MSR: 9000000000029032 <EE,ME,CE,IR,DR> CR: 44004424 XER: 000fffff
TASK = c0000001187dcad0[3143] 'perf' THREAD: c000000118e78000 CPU: 1
GPR00: c0000000000cb46c c000000118e7b7f0 c0000000009866a0 0000000000000020
GPR04: 0000000000000000 000000000000001d 0000000000000000 0000000000000001
GPR08: c0000000009bed68 c00000000086dff8 c000000000a5bf10 0000000000000001
GPR12: 0000000024004422 c00000000ffff200 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000018 00000000101150f4
GPR20: 0000000010206b40 0000000000000000 0000000000000000 00000000101150f4
GPR24: c0000001199090c0 0000000000000001 0000000000000000 0000000000000001
GPR28: 0000000000000000 0000000000000000 c0000000008ec290 0000000000000000
NIP [c0000000000cb470] .task_bp_pinned+0x5c/0x12c
LR [c0000000000cb46c] .task_bp_pinned+0x58/0x12c
Call Trace:
[c000000118e7b7f0] [c0000000000cb46c] .task_bp_pinned+0x58/0x12c (unreliable)
[c000000118e7b8a0] [c0000000000cb584] .toggle_bp_task_slot+0x44/0xe4
[c000000118e7b940] [c0000000000cb6c8] .toggle_bp_slot+0xa4/0x164
[c000000118e7b9f0] [c0000000000cbafc] .release_bp_slot+0x44/0x6c
[c000000118e7ba80] [c0000000000c4178] .bp_perf_event_destroy+0x10/0x24
[c000000118e7bb00] [c0000000000c4aec] .free_event+0x180/0x1bc
[c000000118e7bbc0] [c0000000000c54c4] .perf_event_release_kernel+0x14c/0x170
Reported-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Because cgroup_fork() is ran before sched_fork() [ from copy_process() ]
and the child's pid is not yet visible the child is pinned to its
cgroup. Therefore we can silence this warning.
A nicer solution would be moving cgroup_fork() to right after
dup_task_struct() and exclude PF_STARTING from task_subsys_state().
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The task_group() function returns a pointer that must be protected
by either RCU, the ->alloc_lock, or the cgroup lock (see the
rcu_dereference_check() in task_subsys_state(), which is invoked by
task_group()). The wake_affine() function currently does none of these,
which means that a concurrent update would be within its rights to free
the structure returned by task_group(). Because wake_affine() uses this
structure only to compute load-balancing heuristics, there is no reason
to acquire either of the two locks.
Therefore, this commit introduces an RCU read-side critical section that
starts before the first call to task_group() and ends after the last use
of the "tg" pointer returned from task_group(). Thanks to Li Zefan for
pointing out the need to extend the RCU read-side critical section from
that proposed by the original patch.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Certain architectures (such as PowerPC) have a need to clean up data
structures before a breakpoint is unregistered. This introduces an
arch-specific hook in release_bp_slot() along with a weak definition
in the form of a stub function.
Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Commit 3a101d05 (sched: adjust when cpu_active and cpuset
configurations are updated during cpu on/offlining) added
hotplug notifiers marked with __cpuexit; however, ia64 drops
text in __cpuexit during link unlike x86.
This means that functions which are referenced during init but used
only for cpu hot unplugging afterwards shouldn't be marked with
__cpuexit. Drop __cpuexit from those functions.
Reported-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Tony Luck <tony.luck@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <4C1FDF5B.1040301@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
fastpath_timer_check()->thread_group_cputimer() is racy and
unneeded.
It is racy because another thread can clear ->running before
thread_group_cputimer() takes cputimer->lock. In this case
thread_group_cputimer() will set ->running = true again and call
thread_group_cputime(). But since we do not hold tasklist or
siglock, we can race with fork/exit and copy the wrong results
into cputimer->cputime.
It is unneeded because if ->running == true we can just use
the numbers in cputimer->cputime we already have.
Change fastpath_timer_check() to copy cputimer->cputime into
the local variable under cputimer->lock. We do not re-check
->running under cputimer->lock, run_posix_cpu_timers() does
this check later.
Note: we can add more optimizations on top of this change.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100611180446.GA13025@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
run_posix_cpu_timers() doesn't work if current has already passed
exit_notify(). This was needed to prevent the races with do_wait().
Since ea6d290c ->signal is always valid and can't go away. We can
remove the "tsk->exit_state == 0" in fastpath_timer_check() and
convert run_posix_cpu_timers() to use lock_task_sighand().
Note: it makes sense to take group_leader's sighand instead, the
sub-thread still uses CPU after release_task(). But we need more
changes to do this.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100610231018.GA25942@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
thread_group_cputime() looks as if it is rcu-safe, but in fact this
was wrong until ea6d290c which pins task->signal to task_struct.
It checks ->sighand != NULL under rcu, but this can't help if ->signal
can go away. Fortunately the caller either holds ->siglock, or it is
fastpath_timer_check() which uses current and checks exit_state == 0.
- Since ea6d290c commit tsk->signal is stable, we can read it first
and avoid the initialization from INIT_CPUTIME.
- Even if tsk->signal is always valid, we still have to check it
is safe to use next_thread() under rcu_read_lock(). Currently
the code checks ->sighand != NULL, change it to use pid_alive()
which is commonly used to ensure the task wasn't unhashed before
we take rcu_read_lock().
Add the comment to explain this check.
- Change the main loop to use the while_each_thread() helper.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100610230956.GA25921@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
account_group_xxx() functions check ->exit_state to ensure that
current->signal is valid and can't go away. This is not needed
since ea6d290c, task->signal is pinned to task_struct.
The comment and another hack in account_group_exec_runtime() refers
to task_rq_unlock_wait() which was already removed by b7b8ff63.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100610230952.GA25914@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
__sched_setscheduler() takes lock_task_sighand() to access task->signal.
This is not needed since ea6d290c, ->signal can't go away.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100610230944.GA25903@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Docbook fails in sched_fair.c due to comments added in the asymmetric
packing patch series.
This fixes these errors. No code changes.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <24737.1276135581@neuling.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The CPU power test is the wrong way around in fix_small_capacity.
This was due to a small changes made in the posted patch on lkml to what
was was taken upstream.
This patch fixes asymmetric packing for POWER7.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <12629.1276124617@neuling.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Commit e70971591 ("sched: Optimize unused cgroup configuration") introduced
an imbalanced scheduling bug.
If we do not use CGROUP, function update_h_load won't update h_load. When the
system has a large number of tasks far more than logical CPU number, the
incorrect cfs_rq[cpu]->h_load value will cause load_balance() to pull too
many tasks to the local CPU from the busiest CPU. So the busiest CPU keeps
going in a round robin. That will hurt performance.
The issue was found originally by a scientific calculation workload that
developed by Yanmin. With that commit, the workload performance drops
about 40%.
CPU before after
00 : 2 : 7
01 : 1 : 7
02 : 11 : 6
03 : 12 : 7
04 : 6 : 6
05 : 11 : 7
06 : 10 : 6
07 : 12 : 7
08 : 11 : 6
09 : 12 : 6
10 : 1 : 6
11 : 1 : 6
12 : 6 : 6
13 : 2 : 6
14 : 2 : 6
15 : 1 : 6
Reviewed-by: Yanmin zhang <yanmin.zhang@intel.com>
Signed-off-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1276754893.9452.5442.camel@debian>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Chris Wedgwood reports that 39c0cbe (sched: Rate-limit nohz) causes a
serial console regression, unresponsiveness, and indeed it does. The
reason is that the nohz code is skipped even when the tick was already
stopped before the nohz_ratelimit(cpu) condition changed.
Move the nohz_ratelimit() check to the other conditions which prevent
long idle sleeps.
Reported-by: Chris Wedgwood <cw@f00f.org>
Tested-by: Brian Bloniarz <bmb@athenacr.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg KH <gregkh@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Jef Driesen <jefdriesen@telenet.be>
LKML-Reference: <1276790557.27822.516.camel@twins>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Define what happens when a we view a uid from one user_namespace
in another user_namepece.
- If the user namespaces are the same no mapping is necessary.
- For most cases of difference use overflowuid and overflowgid,
the uid and gid currently used for 16bit apis when we have a 32bit uid
that does fit in 16bits. Effectively the situation is the same,
we want to return a uid or gid that is not assigned to any user.
- For the case when we happen to be mapping the uid or gid of the
creator of the target user namespace use uid 0 and gid as confusing
that user with root is not a problem.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Some recent uses of RCU make use of workqueues. In these uses, execution
within the context of a specific workqueue takes the place of the usual
RCU read-side primitives such as rcu_read_lock(), and flushing of workqueues
takes the place of the usual RCU grace-period primitives. Checking for
correct use of rcu_dereference() in such cases requires a test of whether
the code is executing in the context of a particular workqueue. This
commit adds an in_workqueue_context() function that provides this test.
This new function is only defined when lockdep is enabled, which allows
it to be used as the second argument of rcu_dereference_check().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Helps finding racy users of call_rcu(), which results in hangs because list
entries are overwritten and/or skipped.
Changelog since v4:
- Bissectability is now OK
- Now generate a WARN_ON_ONCE() for non-initialized rcu_head passed to
call_rcu(). Statically initialized objects are detected with
object_is_static().
- Rename rcu_head_init_on_stack to init_rcu_head_on_stack.
- Remove init_rcu_head() completely.
Changelog since v3:
- Include comments from Lai Jiangshan
This new patch version is based on the debugobjects with the newly introduced
"active state" tracker.
Non-initialized entries are all considered as "statically initialized". An
activation fixup (triggered by call_rcu()) takes care of performing the debug
object initialization without issuing any warning. Since we cannot increase the
size of struct rcu_head, I don't see much room to put an identifier for
statically initialized rcu_head structures. So for now, we have to live without
"activation without explicit init" detection. But the main purpose of this debug
option is to detect double-activations (double call_rcu() use of a rcu_head
before the callback is executed), which is correctly addressed here.
This also detects potential internal RCU callback corruption, which would cause
the callbacks to be executed twice.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: David S. Miller <davem@davemloft.net>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
CC: akpm@linux-foundation.org
CC: mingo@elte.hu
CC: laijs@cn.fujitsu.com
CC: dipankar@in.ibm.com
CC: josh@joshtriplett.org
CC: dvhltc@us.ibm.com
CC: niv@us.ibm.com
CC: tglx@linutronix.de
CC: peterz@infradead.org
CC: rostedt@goodmis.org
CC: Valdis.Kletnieks@vt.edu
CC: dhowells@redhat.com
CC: eric.dumazet@gmail.com
CC: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
With the addition of the code to shrink the kernel tracepoint
infrastructure, we lost kprobes being traced by perf. The reason
is that I tested if the "tp_event->class->perf_probe" existed before
enabling it. This prevents "ftrace only" events (like the function
trace events) from being enabled by perf.
Unfortunately, kprobe events do not use perf_probe. This causes
kprobes to be missed by perf. To fix this, we add the test to
see if "tp_event->class->reg" exists as well as perf_probe.
Normal trace events have only "perf_probe" but no "reg" function,
and kprobes and syscalls have the "reg" but no "perf_probe".
The ftrace unique events do not have either, so this is a valid
test. If a kprobe or syscall is not to be probed by perf, the
"reg" function is called anyway, and will return a failure and
prevent perf from probing it.
Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
tracing: Fix null pointer deref with SEND_SIG_FORCED
perf: Fix signed comparison in perf_adjust_period()
powerpc/oprofile: fix potential buffer overrun in op_model_cell.c
perf symbols: Set the DSO long name when using symbol_conf.vmlinux_name
Saving platform non-volatile state may be required for suspend to RAM as
well as hibernation. Move it to more generic code.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>
We have been resisting new ftrace plugins and removing existing
ones, and kmemtrace has been superseded by kmem trace events
and perf-kmem, so we remove it.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
[ remove kmemtrace from the makefile, handle slob too ]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
The set_type() function can change the chip implementation when the
trigger mode changes. That might result in using an non-initialized
irq chip when called from __setup_irq() or when called via
set_irq_type() on an already enabled irq.
The set_irq_type() function should not be called on an enabled irq,
but because we forgot to put a check into it, we have a bunch of users
which grew the habit of doing that and it never blew up as the
function is serialized via desc->lock against all users of desc->chip
and they never hit the non-initialized irq chip issue.
The easy fix for the __setup_irq() issue would be to move the
irq_chip_set_defaults(desc->chip) call after the trigger setting to
make sure that a chip change is covered.
But as we have already users, which do the type setting after
request_irq(), the safe fix for now is to call irq_chip_set_defaults()
from __irq_set_trigger() when desc->set_type() changed the irq chip.
It needs a deeper analysis whether we should refuse to change the chip
on an already enabled irq, but that'd be a large scale change to fix
all the existing users. So that's neither stable nor 2.6.35 material.
Reported-by: Esben Haabendal <eha@doredevelopment.dk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev <linuxppc-dev@ozlabs.org>
Cc: stable@kernel.org
Since now all modification to event->count (and ->prev_count
and ->period_left) are local to a cpu, change then to local64_t so we
avoid the LOCK'ed ops.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Only child counters adding back their values into the parent counter
are responsible for cross-cpu updates to event->count.
So if we pull that out into a new child_count variable, we get an
event->count that is only modified locally.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Create a helper function for those sites that want to read the event count.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Currently there are perf_buffer_alloc() + perf_buffer_init() + some
separate bits, fold it all into a single perf_buffer_alloc() and only
leave the attachment to the event separate.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Clarify some of the transactional group scheduling API details
and change it so that a successfull ->commit_txn also closes
the transaction.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1274803086.5882.1752.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add the capacility to track data mmap()s. This can be used together
with PERF_SAMPLE_ADDR for data profiling.
Signed-off-by: Anton Blanchard <anton@samba.org>
[Updated code for stable perf ABI]
Signed-off-by: Eric B Munson <ebmunson@us.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1274193049-25997-1-git-send-email-ebmunson@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
__DO_TRACE() already calls the callbacks under rcu_read_lock_sched(),
which is sufficient for our needs, avoid doing it again.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Inline perf_swevent_put_recursion_context into perf_tp_event(), this
shrinks the per trace template code footprint and saves a function
call.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Check to see if the group is packed in a sched doman.
This is primarily intended to used at the sibling level. Some cores
like POWER7 prefer to use lower numbered SMT threads. In the case of
POWER7, it can move to lower SMT modes only when higher threads are
idle. When in lower SMT modes, the threads will perform better since
they share less core resources. Hence when we have idle threads, we
want them to be the higher ones.
This adds a hook into f_b_g() called check_asym_packing() to check the
packing. This packing function is run on idle threads. It checks to
see if the busiest CPU in this domain (core in the P7 case) has a
higher CPU number than what where the packing function is being run
on. If it is, calculate the imbalance and return the higher busier
thread as the busiest group to f_b_g(). Here we are assuming a lower
CPU number will be equivalent to a lower SMT thread number.
It also creates a new SD_ASYM_PACKING flag to enable this feature at
any scheduler domain level.
It also creates an arch hook to enable this feature at the sibling
level. The default function doesn't enable this feature.
Based heavily on patch from Peter Zijlstra.
Fixes from Srivatsa Vaddagiri.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <20100608045702.2936CCC897@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Handle cpu capacity being reported as 0 on cores with more number of
hardware threads. For example on a Power7 core with 4 hardware
threads, core power is 1177 and thus power of each hardware thread is
1177/4 = 294. This low power can lead to capacity for each hardware
thread being calculated as 0, which leads to tasks bouncing within the
core madly!
Fix this by reporting capacity for hardware threads as 1, provided
their power is not scaled down significantly because of frequency
scaling or real-time tasks usage of cpu.
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20100608045702.21D03CC895@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In the new push model, all idle CPUs indeed go into nohz mode. There is
still the concept of idle load balancer (performing the load balancing
on behalf of all the idle cpu's in the system). Busy CPU kicks the nohz
balancer when any of the nohz CPUs need idle load balancing.
The kickee CPU does the idle load balancing on behalf of all idle CPUs
instead of the normal idle balance.
This addresses the below two problems with the current nohz ilb logic:
* the idle load balancer continued to have periodic ticks during idle and
wokeup frequently, even though it did not have any rebalancing to do on
behalf of any of the idle CPUs.
* On x86 and CPUs that have APIC timer stoppage on idle CPUs, this
periodic wakeup can result in a periodic additional interrupt on a CPU
doing the timer broadcast.
Also currently we are migrating the unpinned timers from an idle to the cpu
doing idle load balancing (when all the cpus in the system are idle,
there is no idle load balancing cpu and timers get added to the same idle cpu
where the request was made. So the existing optimization works only on semi idle
system).
And In semi idle system, we no longer have periodic ticks on the idle load
balancer CPU. Using that cpu will add more delays to the timers than intended
(as that cpu's timer base may not be uptodate wrt jiffies etc). This was
causing mysterious slowdowns during boot etc.
For now, in the semi idle case, use the nearest busy cpu for migrating timers
from an idle cpu. This is good for power-savings anyway.
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1274486981.2840.46.camel@sbs-t61.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
tickless idle has a negative side effect on update_cpu_load(), which
in turn can affect load balancing behavior.
update_cpu_load() is supposed to be called every tick, to keep track
of various load indicies. With tickless idle, there are no scheduler
ticks called on the idle CPUs. Idle CPUs may still do load balancing
(with idle_load_balance CPU) using the stale cpu_load. It will also
cause problems when all CPUs go idle for a while and become active
again. In this case loads would not degrade as expected.
This is how rq->nr_load_updates change looks like under different
conditions:
<cpu_num> <nr_load_updates change>
All CPUS idle for 10 seconds (HZ=1000)
0 1621
10 496
11 139
12 875
13 1672
14 12
15 21
1 1472
2 2426
3 1161
4 2108
5 1525
6 701
7 249
8 766
9 1967
One CPU busy rest idle for 10 seconds
0 10003
10 601
11 95
12 966
13 1597
14 114
15 98
1 3457
2 93
3 6679
4 1425
5 1479
6 595
7 193
8 633
9 1687
All CPUs busy for 10 seconds
0 10026
10 10026
11 10026
12 10026
13 10025
14 10025
15 10025
1 10026
2 10026
3 10026
4 10026
5 10026
6 10026
7 10026
8 10026
9 10026
That is update_cpu_load works properly only when all CPUs are busy.
If all are idle, all the CPUs get way lower updates. And when few
CPUs are busy and rest are idle, only busy and ilb CPU does proper
updates and rest of the idle CPUs will do lower updates.
The patch keeps track of when a last update was done and fixes up
the load avg based on current time.
On one of my test system SPECjbb with warehouse 1..numcpus, patch
improves throughput numbers by ~1% (average of 6 runs). On another
test system (with different domain hierarchy) there is no noticable
change in perf.
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <AANLkTilLtDWQsAUrIxJ6s04WTgmw9GuOODc5AOrYsaR5@mail.gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
- Contrary to what 6d558c3a says, there is no need to reload
prev = rq->curr after the context switch. You always schedule
back to where you came from, prev must be equal to current
even if cpu/rq was changed.
- This also means reacquire_kernel_lock() can use prev instead
of current.
- No need to reassign switch_count if reacquire_kernel_lock()
reports need_resched(), we can just move the initial assignment
down, under the "need_resched_nonpreemptible:" label.
- Try to update the comment after context_switch().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100519125711.GA30199@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
For people who otherwise get to write: cpu_clock(smp_processor_id()),
there is now: local_clock().
Also, as per suggestion from Andrew, provide some documentation on
the various clock interfaces, and minimize the unsigned long long vs
u64 mess.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jens Axboe <jaxboe@fusionio.com>
LKML-Reference: <1275052414.1645.52.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
