e40f74c535
1263 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Valentin Schneider
|
d707faa64d |
sched/core: Add missing completion for affine_move_task() waiters
Qian reported that some fuzzer issuing sched_setaffinity() ends up stuck on
a wait_for_completion(). The problematic pattern seems to be:
affine_move_task()
// task_running() case
stop_one_cpu();
wait_for_completion(&pending->done);
Combined with, on the stopper side:
migration_cpu_stop()
// Task moved between unlocks and scheduling the stopper
task_rq(p) != rq &&
// task_running() case
dest_cpu >= 0
=> no complete_all()
This can happen with both PREEMPT and !PREEMPT, although !PREEMPT should
be more likely to see this given the targeted task has a much bigger window
to block and be woken up elsewhere before the stopper runs.
Make migration_cpu_stop() always look at pending affinity requests; signal
their completion if the stopper hits a rq mismatch but the task is
still within its allowed mask. When Migrate-Disable isn't involved, this
matches the previous set_cpus_allowed_ptr() vs migration_cpu_stop()
behaviour.
Fixes:
|
||
Frederic Weisbecker
|
6775de4984 |
context_tracking: Only define schedule_user() on !HAVE_CONTEXT_TRACKING_OFFSTACK archs
schedule_user() was traditionally used by the entry code's tail to preempt userspace after the call to user_enter(). Indeed the call to user_enter() used to be performed upon syscall exit slow path which was right before the last opportunity to schedule() while resuming to userspace. The context tracking state had to be saved on the task stack and set back to CONTEXT_KERNEL temporarily in order to safely switch to another task. Only a few archs use it now (namely sparc64 and powerpc64) and those implementing HAVE_CONTEXT_TRACKING_OFFSTACK definetly can't rely on it. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201117151637.259084-5-frederic@kernel.org |
||
|
Frederic Weisbecker
|
9f68b5b74c |
sched: Detect call to schedule from critical entry code
Detect calls to schedule() between user_enter() and user_exit(). Those are symptoms of early entry code that either forgot to protect a call to schedule() inside exception_enter()/exception_exit() or, in the case of HAVE_CONTEXT_TRACKING_OFFSTACK, enabled interrupts or preemption in a wrong spot. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201117151637.259084-4-frederic@kernel.org |
||
Juri Lelli
|
2279f540ea |
sched/deadline: Fix priority inheritance with multiple scheduling classes
Glenn reported that "an application [he developed produces] a BUG in deadline.c when a SCHED_DEADLINE task contends with CFS tasks on nested PTHREAD_PRIO_INHERIT mutexes. I believe the bug is triggered when a CFS task that was boosted by a SCHED_DEADLINE task boosts another CFS task (nested priority inheritance). ------------[ cut here ]------------ kernel BUG at kernel/sched/deadline.c:1462! invalid opcode: 0000 [#1] PREEMPT SMP CPU: 12 PID: 19171 Comm: dl_boost_bug Tainted: ... Hardware name: ... RIP: 0010:enqueue_task_dl+0x335/0x910 Code: ... RSP: 0018:ffffc9000c2bbc68 EFLAGS: 00010002 RAX: 0000000000000009 RBX: ffff888c0af94c00 RCX: ffffffff81e12500 RDX: 000000000000002e RSI: ffff888c0af94c00 RDI: ffff888c10b22600 RBP: ffffc9000c2bbd08 R08: 0000000000000009 R09: 0000000000000078 R10: ffffffff81e12440 R11: ffffffff81e1236c R12: ffff888bc8932600 R13: ffff888c0af94eb8 R14: ffff888c10b22600 R15: ffff888bc8932600 FS: 00007fa58ac55700(0000) GS:ffff888c10b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa58b523230 CR3: 0000000bf44ab003 CR4: 00000000007606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: ? intel_pstate_update_util_hwp+0x13/0x170 rt_mutex_setprio+0x1cc/0x4b0 task_blocks_on_rt_mutex+0x225/0x260 rt_spin_lock_slowlock_locked+0xab/0x2d0 rt_spin_lock_slowlock+0x50/0x80 hrtimer_grab_expiry_lock+0x20/0x30 hrtimer_cancel+0x13/0x30 do_nanosleep+0xa0/0x150 hrtimer_nanosleep+0xe1/0x230 ? __hrtimer_init_sleeper+0x60/0x60 __x64_sys_nanosleep+0x8d/0xa0 do_syscall_64+0x4a/0x100 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fa58b52330d ... ---[ end trace 0000000000000002 ]— He also provided a simple reproducer creating the situation below: So the execution order of locking steps are the following (N1 and N2 are non-deadline tasks. D1 is a deadline task. M1 and M2 are mutexes that are enabled * with priority inheritance.) Time moves forward as this timeline goes down: N1 N2 D1 | | | | | | Lock(M1) | | | | | | Lock(M2) | | | | | | Lock(M2) | | | | Lock(M1) | | (!!bug triggered!) | Daniel reported a similar situation as well, by just letting ksoftirqd run with DEADLINE (and eventually block on a mutex). Problem is that boosted entities (Priority Inheritance) use static DEADLINE parameters of the top priority waiter. However, there might be cases where top waiter could be a non-DEADLINE entity that is currently boosted by a DEADLINE entity from a different lock chain (i.e., nested priority chains involving entities of non-DEADLINE classes). In this case, top waiter static DEADLINE parameters could be null (initialized to 0 at fork()) and replenish_dl_entity() would hit a BUG(). Fix this by keeping track of the original donor and using its parameters when a task is boosted. Reported-by: Glenn Elliott <glenn@aurora.tech> Reported-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Juri Lelli <juri.lelli@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201117061432.517340-1-juri.lelli@redhat.com |
||
Peter Zijlstra
|
ec618b84f6 |
sched: Fix rq->nr_iowait ordering
schedule() ttwu()
deactivate_task(); if (p->on_rq && ...) // false
atomic_dec(&task_rq(p)->nr_iowait);
if (prev->in_iowait)
atomic_inc(&rq->nr_iowait);
Allows nr_iowait to be decremented before it gets incremented,
resulting in more dodgy IO-wait numbers than usual.
Note that because we can now do ttwu_queue_wakelist() before
p->on_cpu==0, we lose the natural ordering and have to further delay
the decrement.
Fixes:
|
||
|
Valentin Schneider
|
3aef1551e9 |
sched: Remove select_task_rq()'s sd_flag parameter
Only select_task_rq_fair() uses that parameter to do an actual domain search, other classes only care about what kind of wakeup is happening (fork, exec, or "regular") and thus just translate the flag into a wakeup type. WF_TTWU and WF_EXEC have just been added, use these along with WF_FORK to encode the wakeup types we care about. For select_task_rq_fair(), we can simply use the shiny new WF_flag : SD_flag mapping. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201102184514.2733-3-valentin.schneider@arm.com |
||
|
Peter Zijlstra
|
12fa97c64d | Merge branch 'sched/migrate-disable' | ||
|
Valentin Schneider
|
c777d84710 |
sched: Comment affine_move_task()
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201013140116.26651-2-valentin.schneider@arm.com |
||
|
Valentin Schneider
|
885b3ba47a |
sched: Deny self-issued __set_cpus_allowed_ptr() when migrate_disable()
migrate_disable();
set_cpus_allowed_ptr(current, {something excluding task_cpu(current)});
affine_move_task(); <-- never returns
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201013140116.26651-1-valentin.schneider@arm.com
|
||
|
Peter Zijlstra
|
a7c81556ec |
sched: Fix migrate_disable() vs rt/dl balancing
In order to minimize the interference of migrate_disable() on lower priority tasks, which can be deprived of runtime due to being stuck below a higher priority task. Teach the RT/DL balancers to push away these higher priority tasks when a lower priority task gets selected to run on a freshly demoted CPU (pull). This adds migration interference to the higher priority task, but restores bandwidth to system that would otherwise be irrevocably lost. Without this it would be possible to have all tasks on the system stuck on a single CPU, each task preempted in a migrate_disable() section with a single high priority task running. This way we can still approximate running the M highest priority tasks on the system. Migrating the top task away is (ofcourse) still subject to migrate_disable() too, which means the lower task is subject to an interference equivalent to the worst case migrate_disable() section. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102347.499155098@infradead.org |
||
|
Peter Zijlstra
|
ded467dc83 |
sched, lockdep: Annotate ->pi_lock recursion
There's a valid ->pi_lock recursion issue where the actual PI code tries to wake up the stop task. Make lockdep aware so it doesn't complain about this. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102347.406912197@infradead.org |
||
Thomas Gleixner
|
3015ef4b98 |
sched/core: Make migrate disable and CPU hotplug cooperative
On CPU unplug tasks which are in a migrate disabled region cannot be pushed to a different CPU until they returned to migrateable state. Account the number of tasks on a runqueue which are in a migrate disabled section and make the hotplug wait mechanism respect that. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102347.067278757@infradead.org |
||
|
Peter Zijlstra
|
6d337eab04 |
sched: Fix migrate_disable() vs set_cpus_allowed_ptr()
Concurrent migrate_disable() and set_cpus_allowed_ptr() has interesting features. We rely on set_cpus_allowed_ptr() to not return until the task runs inside the provided mask. This expectation is exported to userspace. This means that any set_cpus_allowed_ptr() caller must wait until migrate_enable() allows migrations. At the same time, we don't want migrate_enable() to schedule, due to patterns like: preempt_disable(); migrate_disable(); ... migrate_enable(); preempt_enable(); And: raw_spin_lock(&B); spin_unlock(&A); this means that when migrate_enable() must restore the affinity mask, it cannot wait for completion thereof. Luck will have it that that is exactly the case where there is a pending set_cpus_allowed_ptr(), so let that provide storage for the async stop machine. Much thanks to Valentin who used TLA+ most effective and found lots of 'interesting' cases. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102346.921768277@infradead.org |
||
|
Peter Zijlstra
|
af449901b8 |
sched: Add migrate_disable()
Add the base migrate_disable() support (under protest). While migrate_disable() is (currently) required for PREEMPT_RT, it is also one of the biggest flaws in the system. Notably this is just the base implementation, it is broken vs sched_setaffinity() and hotplug, both solved in additional patches for ease of review. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102346.818170844@infradead.org |
||
|
Peter Zijlstra
|
9cfc3e18ad |
sched: Massage set_cpus_allowed()
Thread a u32 flags word through the *set_cpus_allowed*() callchain. This will allow adding behavioural tweaks for future users. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102346.729082820@infradead.org |
||
|
Peter Zijlstra
|
120455c514 |
sched: Fix hotplug vs CPU bandwidth control
Since we now migrate tasks away before DYING, we should also move bandwidth unthrottle, otherwise we can gain tasks from unthrottle after we expect all tasks to be gone already. Also; it looks like the RT balancers don't respect cpu_active() and instead rely on rq->online in part, complete this. This too requires we do set_rq_offline() earlier to match the cpu_active() semantics. (The bigger patch is to convert RT to cpu_active() entirely) Since set_rq_online() is called from sched_cpu_activate(), place set_rq_offline() in sched_cpu_deactivate(). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102346.639538965@infradead.org |
||
|
Thomas Gleixner
|
1cf12e08bc |
sched/hotplug: Consolidate task migration on CPU unplug
With the new mechanism which kicks tasks off the outgoing CPU at the end of schedule() the situation on an outgoing CPU right before the stopper thread brings it down completely is: - All user tasks and all unbound kernel threads have either been migrated away or are not running and the next wakeup will move them to a online CPU. - All per CPU kernel threads, except cpu hotplug thread and the stopper thread have either been unbound or parked by the responsible CPU hotplug callback. That means that at the last step before the stopper thread is invoked the cpu hotplug thread is the last legitimate running task on the outgoing CPU. Add a final wait step right before the stopper thread is kicked which ensures that any still running tasks on the way to park or on the way to kick themself of the CPU are either sleeping or gone. This allows to remove the migrate_tasks() crutch in sched_cpu_dying(). If sched_cpu_dying() detects that there is still another running task aside of the stopper thread then it will explode with the appropriate fireworks. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102346.547163969@infradead.org |
||
|
Thomas Gleixner
|
f2469a1fb4 |
sched/core: Wait for tasks being pushed away on hotplug
RT kernels need to ensure that all tasks which are not per CPU kthreads have left the outgoing CPU to guarantee that no tasks are force migrated within a migrate disabled section. There is also some desire to (ab)use fine grained CPU hotplug control to clear a CPU from active state to force migrate tasks which are not per CPU kthreads away for power control purposes. Add a mechanism which waits until all tasks which should leave the CPU after the CPU active flag is cleared have moved to a different online CPU. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102346.377836842@infradead.org |
||
|
Peter Zijlstra
|
2558aacff8 |
sched/hotplug: Ensure only per-cpu kthreads run during hotplug
In preparation for migrate_disable(), make sure only per-cpu kthreads are allowed to run on !active CPUs. This is ran (as one of the very first steps) from the cpu-hotplug task which is a per-cpu kthread and completion of the hotplug operation only requires such tasks. This constraint enables the migrate_disable() implementation to wait for completion of all migrate_disable regions on this CPU at hotplug time without fear of any new ones starting. This replaces the unlikely(rq->balance_callbacks) test at the tail of context_switch with an unlikely(rq->balance_work), the fast path is not affected. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102346.292709163@infradead.org |
||
|
Peter Zijlstra
|
565790d28b |
sched: Fix balance_callback()
The intent of balance_callback() has always been to delay executing balancing operations until the end of the current rq->lock section. This is because balance operations must often drop rq->lock, and that isn't safe in general. However, as noted by Scott, there were a few holes in that scheme; balance_callback() was called after rq->lock was dropped, which means another CPU can interleave and touch the callback list. Rework code to call the balance callbacks before dropping rq->lock where possible, and otherwise splice the balance list onto a local stack. This guarantees that the balance list must be empty when we take rq->lock. IOW, we'll only ever run our own balance callbacks. Reported-by: Scott Wood <swood@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102346.203901269@infradead.org |
||
|
Peter Zijlstra
|
a8b62fd085 |
stop_machine: Add function and caller debug info
Crashes in stop-machine are hard to connect to the calling code, add a little something to help with that. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lkml.kernel.org/r/20201023102346.116513635@infradead.org |
||
|
Thomas Gleixner
|
345a957fcc |
sched: Reenable interrupts in do_sched_yield()
do_sched_yield() invokes schedule() with interrupts disabled which is
not allowed. This goes back to the pre git era to commit a6efb709806c
("[PATCH] irqlock patch 2.5.27-H6") in the history tree.
Reenable interrupts and remove the misleading comment which "explains" it.
Fixes:
|
||
|
Juri Lelli
|
a73f863af4 |
sched/features: Fix !CONFIG_JUMP_LABEL case
Commit: |
||
Linus Torvalds
|
edaa5ddf38 |
Scheduler changes for v5.10:
- Reorganize & clean up the SD* flags definitions and add a bunch
of sanity checks. These new checks caught quite a few bugs or at
least inconsistencies, resulting in another set of patches.
- Rseq updates, add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ
- Add a new tracepoint to improve CPU capacity tracking
- Improve overloaded SMP system load-balancing behavior
- Tweak SMT balancing
- Energy-aware scheduling updates
- NUMA balancing improvements
- Deadline scheduler fixes and improvements
- CPU isolation fixes
- Misc cleanups, simplifications and smaller optimizations.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----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=bXy6
-----END PGP SIGNATURE-----
Merge tag 'sched-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- reorganize & clean up the SD* flags definitions and add a bunch of
sanity checks. These new checks caught quite a few bugs or at least
inconsistencies, resulting in another set of patches.
- rseq updates, add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ
- add a new tracepoint to improve CPU capacity tracking
- improve overloaded SMP system load-balancing behavior
- tweak SMT balancing
- energy-aware scheduling updates
- NUMA balancing improvements
- deadline scheduler fixes and improvements
- CPU isolation fixes
- misc cleanups, simplifications and smaller optimizations
* tag 'sched-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (42 commits)
sched/deadline: Unthrottle PI boosted threads while enqueuing
sched/debug: Add new tracepoint to track cpu_capacity
sched/fair: Tweak pick_next_entity()
rseq/selftests: Test MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ
rseq/selftests,x86_64: Add rseq_offset_deref_addv()
rseq/membarrier: Add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ
sched/fair: Use dst group while checking imbalance for NUMA balancer
sched/fair: Reduce busy load balance interval
sched/fair: Minimize concurrent LBs between domain level
sched/fair: Reduce minimal imbalance threshold
sched/fair: Relax constraint on task's load during load balance
sched/fair: Remove the force parameter of update_tg_load_avg()
sched/fair: Fix wrong cpu selecting from isolated domain
sched: Remove unused inline function uclamp_bucket_base_value()
sched/rt: Disable RT_RUNTIME_SHARE by default
sched/deadline: Fix stale throttling on de-/boosted tasks
sched/numa: Use runnable_avg to classify node
sched/topology: Move sd_flag_debug out of #ifdef CONFIG_SYSCTL
MAINTAINERS: Add myself as SCHED_DEADLINE reviewer
sched/topology: Move SD_DEGENERATE_GROUPS_MASK out of linux/sched/topology.h
...
|
||
Vincent Donnefort
|
51cf18c90c |
sched/debug: Add new tracepoint to track cpu_capacity
rq->cpu_capacity is a key element in several scheduler parts, such as EAS task placement and load balancing. Tracking this value enables testing and/or debugging by a toolkit. Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/1598605249-72651-1-git-send-email-vincent.donnefort@arm.com |
||
YueHaibing
|
51bd5121c4 |
sched: Remove unused inline function uclamp_bucket_base_value()
There is no caller in tree, so can remove it. Signed-off-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lkml.kernel.org/r/20200922132410.48440-1-yuehaibing@huawei.com |
||
Sebastian Andrzej Siewior
|
c1cecf884a |
sched: Cache task_struct::flags in sched_submit_work()
sched_submit_work() is considered to be a hot path. The preempt_disable() instruction is a compiler barrier and forces the compiler to load task_struct::flags for the second comparison. By using a local variable, the compiler can load the value once and keep it in a register for the second comparison. Verified on x86-64 with gcc-10. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200819200025.lqvmyefqnbok5i4f@linutronix.de |
||
Gustavo A. R. Silva
|
df561f6688 |
treewide: Use fallthrough pseudo-keyword
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> |
||
|
Linus Torvalds
|
1195d58f00 |
Two fixes: fix a new tracepoint's output value, and fix the formatting of show-state syslog printouts.
Signed-off-by: Ingo Molnar <mingo@kernel.org> -----BEGIN PGP SIGNATURE----- iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAl83xXMRHG1pbmdvQGtl cm5lbC5vcmcACgkQEnMQ0APhK1hwRQ/+LC7yzLFMy+OpvuRp/ZY02VtL7oZdCVAS QFYrvmelsPrfbOzfuevGEg5jCHfJ6sL6Q4O06O/ktMUSsQ1HNc+esbTpbea9L/8X ynpujYXDm2AwiYQS2Bh/jDQVIUqJRfyNVpYWgIWTUq4QULh248vx4LGGYk/LQJtD FmuHT/Hc2xIPc01gAY24npSrPOlTJEm9HsfSpFqinXkNFlyocvRc2VwBnI1q/Dxt NVT18/8gb5dpaB3kRJyjuyNz88wJj7Rh65I/NebW9vvWincQzt7OJOutjnx/BzGG k5hMo/oPwCBRlPZ5X1fbsEjv/vXsXYtByNtNMljP3yFaR42F+pZ+5ySYNTtzyya8 BuicHMlrj+kueEXzfYIxcFaI0u0zZV9OCxNQI7T86j5YJyKj2c5xIvkj20r+4U3N 4biuCawvGNyfbw5X8se9yy1EEsw36UaeKNpoMQKcdpGDVskj2POMcyC06qMqahXX /LcIwKyXDwCKbJOz+NOQNY4ZvJSS3kcCYfTmEcaBs7UR6gFRAlwfrh54SDGLp8au t6MEj5GI51RWjo8S0KFBhqg+1sNqdRw2mvcabeRX1vHb/ter3AcHi2of4bSoAF4E GRKK2gfAkmvGc7cLjHEWvSjUPBS/gQgzNMhnyyFL8fEiL/juY5fCLnamuajWEmnF k6LA71AwkNY= =ffEv -----END PGP SIGNATURE----- Merge tag 'sched-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "Two fixes: fix a new tracepoint's output value, and fix the formatting of show-state syslog printouts" * tag 'sched-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/debug: Fix the alignment of the show-state debug output sched: Fix use of count for nr_running tracepoint |
||
Libing Zhou
|
cc172ff301 |
sched/debug: Fix the alignment of the show-state debug output
Current sysrq(t) output task fields name are not aligned with actual task fields value, e.g.: kernel: sysrq: Show State kernel: task PC stack pid father kernel: systemd S12456 1 0 0x00000000 kernel: Call Trace: kernel: ? __schedule+0x240/0x740 To make it more readable, print fields name together with task fields value in the same line, with fixed width: kernel: sysrq: Show State kernel: task:systemd state:S stack:12920 pid: 1 ppid: 0 flags:0x00000000 kernel: Call Trace: kernel: __schedule+0x282/0x620 Signed-off-by: Libing Zhou <libing.zhou@nokia-sbell.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200814030236.37835-1-libing.zhou@nokia-sbell.com |
||
|
Linus Torvalds
|
6d2b84a4e5 |
This tree adds the sched_set_fifo*() encapsulation APIs to remove
static priority level knowledge from non-scheduler code. The three APIs for non-scheduler code to set SCHED_FIFO are: - sched_set_fifo() - sched_set_fifo_low() - sched_set_normal() These are two FIFO priority levels: default (high), and a 'low' priority level, plus sched_set_normal() to set the policy back to non-SCHED_FIFO. Since the changes affect a lot of non-scheduler code, we kept this in a separate tree. When merging to the latest upstream tree there's a conflict in drivers/spi/spi.c, which can be resolved via: sched_set_fifo(ctlr->kworker_task); Signed-off-by: Ingo Molnar <mingo@kernel.org> -----BEGIN PGP SIGNATURE----- iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAl8pPQIRHG1pbmdvQGtl cm5lbC5vcmcACgkQEnMQ0APhK1j0Jw/+LlSyX6gD2ATy3cizGL7DFPZogD5MVKTb IXbhXH/ACpuPQlBe1+haRLbJj6XfXqbOlAleVKt7eh+jZ1jYjC972RCSTO4566mJ 0v8Iy9kkEeb2TDbYx1H3bnk78lf85t0CB+sCzyKUYFuTrXU04eRj7MtN3vAQyRQU xJg83x/sT5DGdDTP50sL7lpbwk3INWkD0aDCJEaO/a9yHElMsTZiZBKoXxN/s30o FsfzW56jqtng771H2bo8ERN7+abwJg10crQU5mIaLhacNMETuz0NZ/f8fY/fydCL Ju8HAdNKNXyphWkAOmixQuyYtWKe2/GfbHg8hld0jmpwxkOSTgZjY+pFcv7/w306 g2l1TPOt8e1n5jbfnY3eig+9Kr8y0qHkXPfLfgRqKwMMaOqTTYixEzj+NdxEIRX9 Kr7oFAv6VEFfXGSpb5L1qyjIGVgQ5/JE/p3OC3GHEsw5VKiy5yjhNLoSmSGzdS61 1YurVvypSEUAn3DqTXgeGX76f0HH365fIKqmbFrUWxliF+YyflMhtrj2JFtejGzH Md3RgAzxusE9S6k3gw1ev4byh167bPBbY8jz0w3Gd7IBRKy9vo92h6ZRYIl6xeoC BU2To1IhCAydIr6hNsIiCSDTgiLbsYQzPuVVovUxNh+l1ZvKV2X+csEHhs8oW4pr 4BRU7dKL2NE= =/7JH -----END PGP SIGNATURE----- Merge tag 'sched-fifo-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull sched/fifo updates from Ingo Molnar: "This adds the sched_set_fifo*() encapsulation APIs to remove static priority level knowledge from non-scheduler code. The three APIs for non-scheduler code to set SCHED_FIFO are: - sched_set_fifo() - sched_set_fifo_low() - sched_set_normal() These are two FIFO priority levels: default (high), and a 'low' priority level, plus sched_set_normal() to set the policy back to non-SCHED_FIFO. Since the changes affect a lot of non-scheduler code, we kept this in a separate tree" * tag 'sched-fifo-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) sched,tracing: Convert to sched_set_fifo() sched: Remove sched_set_*() return value sched: Remove sched_setscheduler*() EXPORTs sched,psi: Convert to sched_set_fifo_low() sched,rcutorture: Convert to sched_set_fifo_low() sched,rcuperf: Convert to sched_set_fifo_low() sched,locktorture: Convert to sched_set_fifo() sched,irq: Convert to sched_set_fifo() sched,watchdog: Convert to sched_set_fifo() sched,serial: Convert to sched_set_fifo() sched,powerclamp: Convert to sched_set_fifo() sched,ion: Convert to sched_set_normal() sched,powercap: Convert to sched_set_fifo*() sched,spi: Convert to sched_set_fifo*() sched,mmc: Convert to sched_set_fifo*() sched,ivtv: Convert to sched_set_fifo*() sched,drm/scheduler: Convert to sched_set_fifo*() sched,msm: Convert to sched_set_fifo*() sched,psci: Convert to sched_set_fifo*() sched,drbd: Convert to sched_set_fifo*() ... |
||
|
Linus Torvalds
|
e4cbce4d13 |
The main changes in this cycle were:
- Improve uclamp performance by using a static key for the fast path
- Add the "sched_util_clamp_min_rt_default" sysctl, to optimize for
better power efficiency of RT tasks on battery powered devices.
(The default is to maximize performance & reduce RT latencies.)
- Improve utime and stime tracking accuracy, which had a fixed boundary
of error, which created larger and larger relative errors as the values
become larger. This is now replaced with more precise arithmetics,
using the new mul_u64_u64_div_u64() helper in math64.h.
- Improve the deadline scheduler, such as making it capacity aware
- Improve frequency-invariant scheduling
- Misc cleanups in energy/power aware scheduling
- Add sched_update_nr_running tracepoint to track changes to nr_running
- Documentation additions and updates
- Misc cleanups and smaller fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----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=PbO7
-----END PGP SIGNATURE-----
Merge tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Improve uclamp performance by using a static key for the fast path
- Add the "sched_util_clamp_min_rt_default" sysctl, to optimize for
better power efficiency of RT tasks on battery powered devices.
(The default is to maximize performance & reduce RT latencies.)
- Improve utime and stime tracking accuracy, which had a fixed boundary
of error, which created larger and larger relative errors as the
values become larger. This is now replaced with more precise
arithmetics, using the new mul_u64_u64_div_u64() helper in math64.h.
- Improve the deadline scheduler, such as making it capacity aware
- Improve frequency-invariant scheduling
- Misc cleanups in energy/power aware scheduling
- Add sched_update_nr_running tracepoint to track changes to nr_running
- Documentation additions and updates
- Misc cleanups and smaller fixes
* tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
sched/doc: Factorize bits between sched-energy.rst & sched-capacity.rst
sched/doc: Document capacity aware scheduling
sched: Document arch_scale_*_capacity()
arm, arm64: Fix selection of CONFIG_SCHED_THERMAL_PRESSURE
Documentation/sysctl: Document uclamp sysctl knobs
sched/uclamp: Add a new sysctl to control RT default boost value
sched/uclamp: Fix a deadlock when enabling uclamp static key
sched: Remove duplicated tick_nohz_full_enabled() check
sched: Fix a typo in a comment
sched/uclamp: Remove unnecessary mutex_init()
arm, arm64: Select CONFIG_SCHED_THERMAL_PRESSURE
sched: Cleanup SCHED_THERMAL_PRESSURE kconfig entry
arch_topology, sched/core: Cleanup thermal pressure definition
trace/events/sched.h: fix duplicated word
linux/sched/mm.h: drop duplicated words in comments
smp: Fix a potential usage of stale nr_cpus
sched/fair: update_pick_idlest() Select group with lowest group_util when idle_cpus are equal
sched: nohz: stop passing around unused "ticks" parameter.
sched: Better document ttwu()
sched: Add a tracepoint to track rq->nr_running
...
|
||
Qais Yousef
|
13685c4a08 |
sched/uclamp: Add a new sysctl to control RT default boost value
RT tasks by default run at the highest capacity/performance level. When uclamp is selected this default behavior is retained by enforcing the requested uclamp.min (p->uclamp_req[UCLAMP_MIN]) of the RT tasks to be uclamp_none(UCLAMP_MAX), which is SCHED_CAPACITY_SCALE; the maximum value. This is also referred to as 'the default boost value of RT tasks'. See commit |
||
|
Qais Yousef
|
e65855a52b |
sched/uclamp: Fix a deadlock when enabling uclamp static key
The following splat was caught when setting uclamp value of a task:
BUG: sleeping function called from invalid context at ./include/linux/percpu-rwsem.h:49
cpus_read_lock+0x68/0x130
static_key_enable+0x1c/0x38
__sched_setscheduler+0x900/0xad8
Fix by ensuring we enable the key outside of the critical section in
__sched_setscheduler()
Fixes:
|
||
Qinglang Miao
|
13efa61612 |
sched/uclamp: Remove unnecessary mutex_init()
The uclamp_mutex lock is initialized statically via DEFINE_MUTEX(), it is unnecessary to initialize it runtime via mutex_init(). Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Patrick Bellasi <patrick.bellasi@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lore.kernel.org/r/20200725085629.98292-1-miaoqinglang@huawei.com |
||
Chris Wilson
|
062d3f95b6 |
sched: Warn if garbage is passed to default_wake_function()
Since the default_wake_function() passes its flags onto try_to_wake_up(), warn if those flags collide with internal values. Given that the supplied flags are garbage, no repair can be done but at least alert the user to the damage they are causing. In the belief that these errors should be picked up during testing, the warning is only compiled in under CONFIG_SCHED_DEBUG. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: https://lore.kernel.org/r/20200723201042.18861-1-chris@chris-wilson.co.uk |
||
|
Valentin Schneider
|
25980c7a79 |
arch_topology, sched/core: Cleanup thermal pressure definition
The following commit:
|
||
|
Peter Zijlstra
|
58877d347b |
sched: Better document ttwu()
Dave hit the problem fixed by commit:
|
||
|
Peter Zijlstra
|
015dc08918 | Merge branch 'sched/urgent' | ||
|
Peter Zijlstra
|
d136122f58 |
sched: Fix race against ptrace_freeze_trace()
There is apparently one site that violates the rule that only current
and ttwu() will modify task->state, namely ptrace_{,un}freeze_traced()
will change task->state for a remote task.
Oleg explains:
"TASK_TRACED/TASK_STOPPED was always protected by siglock. In
particular, ttwu(__TASK_TRACED) must be always called with siglock
held. That is why ptrace_freeze_traced() assumes it can safely do
s/TASK_TRACED/__TASK_TRACED/ under spin_lock(siglock)."
This breaks the ordering scheme introduced by commit:
|
||
Phil Auld
|
9d246053a6 |
sched: Add a tracepoint to track rq->nr_running
Add a bare tracepoint trace_sched_update_nr_running_tp which tracks ->nr_running CPU's rq. This is used to accurately trace this data and provide a visualization of scheduler imbalances in, for example, the form of a heat map. The tracepoint is accessed by loading an external kernel module. An example module (forked from Qais' module and including the pelt related tracepoints) can be found at: https://github.com/auldp/tracepoints-helpers.git A script to turn the trace-cmd report output into a heatmap plot can be found at: https://github.com/jirvoz/plot-nr-running The tracepoints are added to add_nr_running() and sub_nr_running() which are in kernel/sched/sched.h. In order to avoid CREATE_TRACE_POINTS in the header a wrapper call is used and the trace/events/sched.h include is moved before sched.h in kernel/sched/core. Signed-off-by: Phil Auld <pauld@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200629192303.GC120228@lorien.usersys.redhat.com |
||
|
Qais Yousef
|
46609ce227 |
sched/uclamp: Protect uclamp fast path code with static key
There is a report that when uclamp is enabled, a netperf UDP test
regresses compared to a kernel compiled without uclamp.
https://lore.kernel.org/lkml/20200529100806.GA3070@suse.de/
While investigating the root cause, there were no sign that the uclamp
code is doing anything particularly expensive but could suffer from bad
cache behavior under certain circumstances that are yet to be
understood.
https://lore.kernel.org/lkml/20200616110824.dgkkbyapn3io6wik@e107158-lin/
To reduce the pressure on the fast path anyway, add a static key that is
by default will skip executing uclamp logic in the
enqueue/dequeue_task() fast path until it's needed.
As soon as the user start using util clamp by:
1. Changing uclamp value of a task with sched_setattr()
2. Modifying the default sysctl_sched_util_clamp_{min, max}
3. Modifying the default cpu.uclamp.{min, max} value in cgroup
We flip the static key now that the user has opted to use util clamp.
Effectively re-introducing uclamp logic in the enqueue/dequeue_task()
fast path. It stays on from that point forward until the next reboot.
This should help minimize the effect of util clamp on workloads that
don't need it but still allow distros to ship their kernels with uclamp
compiled in by default.
SCHED_WARN_ON() in uclamp_rq_dec_id() was removed since now we can end
up with unbalanced call to uclamp_rq_dec_id() if we flip the key while
a task is running in the rq. Since we know it is harmless we just
quietly return if we attempt a uclamp_rq_dec_id() when
rq->uclamp[].bucket[].tasks is 0.
In schedutil, we introduce a new uclamp_is_enabled() helper which takes
the static key into account to ensure RT boosting behavior is retained.
The following results demonstrates how this helps on 2 Sockets Xeon E5
2x10-Cores system.
nouclamp uclamp uclamp-static-key
Hmean send-64 162.43 ( 0.00%) 157.84 * -2.82%* 163.39 * 0.59%*
Hmean send-128 324.71 ( 0.00%) 314.78 * -3.06%* 326.18 * 0.45%*
Hmean send-256 641.55 ( 0.00%) 628.67 * -2.01%* 648.12 * 1.02%*
Hmean send-1024 2525.28 ( 0.00%) 2448.26 * -3.05%* 2543.73 * 0.73%*
Hmean send-2048 4836.14 ( 0.00%) 4712.08 * -2.57%* 4867.69 * 0.65%*
Hmean send-3312 7540.83 ( 0.00%) 7425.45 * -1.53%* 7621.06 * 1.06%*
Hmean send-4096 9124.53 ( 0.00%) 8948.82 * -1.93%* 9276.25 * 1.66%*
Hmean send-8192 15589.67 ( 0.00%) 15486.35 * -0.66%* 15819.98 * 1.48%*
Hmean send-16384 26386.47 ( 0.00%) 25752.25 * -2.40%* 26773.74 * 1.47%*
The perf diff between nouclamp and uclamp-static-key when uclamp is
disabled in the fast path:
8.73% -1.55% [kernel.kallsyms] [k] try_to_wake_up
0.07% +0.04% [kernel.kallsyms] [k] deactivate_task
0.13% -0.02% [kernel.kallsyms] [k] activate_task
The diff between nouclamp and uclamp-static-key when uclamp is enabled
in the fast path:
8.73% -0.72% [kernel.kallsyms] [k] try_to_wake_up
0.13% +0.39% [kernel.kallsyms] [k] activate_task
0.07% +0.38% [kernel.kallsyms] [k] deactivate_task
Fixes:
|
||
|
Qais Yousef
|
d81ae8aac8 |
sched/uclamp: Fix initialization of struct uclamp_rq
struct uclamp_rq was zeroed out entirely in assumption that in the first
call to uclamp_rq_inc() they'd be initialized correctly in accordance to
default settings.
But when next patch introduces a static key to skip
uclamp_rq_{inc,dec}() until userspace opts in to use uclamp, schedutil
will fail to perform any frequency changes because the
rq->uclamp[UCLAMP_MAX].value is zeroed at init and stays as such. Which
means all rqs are capped to 0 by default.
Fix it by making sure we do proper initialization at init without
relying on uclamp_rq_inc() doing it later.
Fixes:
|
||
|
Peter Zijlstra
|
faa2fd7cba | Merge branch 'sched/urgent' | ||
Mathieu Desnoyers
|
ce3614daab |
sched: Fix unreliable rseq cpu_id for new tasks
While integrating rseq into glibc and replacing glibc's sched_getcpu
implementation with rseq, glibc's tests discovered an issue with
incorrect __rseq_abi.cpu_id field value right after the first time
a newly created process issues sched_setaffinity.
For the records, it triggers after building glibc and running tests, and
then issuing:
for x in {1..2000} ; do posix/tst-affinity-static & done
and shows up as:
error: Unexpected CPU 2, expected 0
error: Unexpected CPU 2, expected 0
error: Unexpected CPU 2, expected 0
error: Unexpected CPU 2, expected 0
error: Unexpected CPU 138, expected 0
error: Unexpected CPU 138, expected 0
error: Unexpected CPU 138, expected 0
error: Unexpected CPU 138, expected 0
This is caused by the scheduler invoking __set_task_cpu() directly from
sched_fork() and wake_up_new_task(), thus bypassing rseq_migrate() which
is done by set_task_cpu().
Add the missing rseq_migrate() to both functions. The only other direct
use of __set_task_cpu() is done by init_idle(), which does not involve a
user-space task.
Based on my testing with the glibc test-case, just adding rseq_migrate()
to wake_up_new_task() is sufficient to fix the observed issue. Also add
it to sched_fork() to keep things consistent.
The reason why this never triggered so far with the rseq/basic_test
selftest is unclear.
The current use of sched_getcpu(3) does not typically require it to be
always accurate. However, use of the __rseq_abi.cpu_id field within rseq
critical sections requires it to be accurate. If it is not accurate, it
can cause corruption in the per-cpu data targeted by rseq critical
sections in user-space.
Reported-By: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-By: Florian Weimer <fweimer@redhat.com>
Cc: stable@vger.kernel.org # v4.18+
Link: https://lkml.kernel.org/r/20200707201505.2632-1-mathieu.desnoyers@efficios.com
|
||
|
Peter Zijlstra
|
dbfb089d36 |
sched: Fix loadavg accounting race
The recent commit: |
||
|
Peter Zijlstra
|
8c4890d1c3 |
smp, irq_work: Continue smp_call_function*() and irq_work*() integration
Instead of relying on BUG_ON() to ensure the various data structures line up, use a bunch of horrible unions to make it all automatic. Much of the union magic is to ensure irq_work and smp_call_function do not (yet) see the members of their respective data structures change name. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20200622100825.844455025@infradead.org |
||
|
Peter Zijlstra
|
739f70b476 |
sched/core: s/WF_ON_RQ/WQ_ON_CPU/
Use a better name for this poorly named flag, to avoid confusion... Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Mel Gorman <mgorman@suse.de> Link: https://lkml.kernel.org/r/20200622100825.785115830@infradead.org |
||
|
Peter Zijlstra
|
b6e13e8582 |
sched/core: Fix ttwu() race
Paul reported rcutorture occasionally hitting a NULL deref:
sched_ttwu_pending()
ttwu_do_wakeup()
check_preempt_curr() := check_preempt_wakeup()
find_matching_se()
is_same_group()
if (se->cfs_rq == pse->cfs_rq) <-- *BOOM*
Debugging showed that this only appears to happen when we take the new
code-path from commit:
|
||
|
Juri Lelli
|
740797ce3a |
sched/core: Fix PI boosting between RT and DEADLINE tasks
syzbot reported the following warning:
WARNING: CPU: 1 PID: 6351 at kernel/sched/deadline.c:628
enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504
At deadline.c:628 we have:
623 static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se)
624 {
625 struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
626 struct rq *rq = rq_of_dl_rq(dl_rq);
627
628 WARN_ON(dl_se->dl_boosted);
629 WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline));
[...]
}
Which means that setup_new_dl_entity() has been called on a task
currently boosted. This shouldn't happen though, as setup_new_dl_entity()
is only called when the 'dynamic' deadline of the new entity
is in the past w.r.t. rq_clock and boosted tasks shouldn't verify this
condition.
Digging through the PI code I noticed that what above might in fact happen
if an RT tasks blocks on an rt_mutex hold by a DEADLINE task. In the
first branch of boosting conditions we check only if a pi_task 'dynamic'
deadline is earlier than mutex holder's and in this case we set mutex
holder to be dl_boosted. However, since RT 'dynamic' deadlines are only
initialized if such tasks get boosted at some point (or if they become
DEADLINE of course), in general RT 'dynamic' deadlines are usually equal
to 0 and this verifies the aforementioned condition.
Fix it by checking that the potential donor task is actually (even if
temporary because in turn boosted) running at DEADLINE priority before
using its 'dynamic' deadline value.
Fixes:
|
||
Scott Wood
|
fd844ba9ae |
sched/core: Check cpus_mask, not cpus_ptr in __set_cpus_allowed_ptr(), to fix mask corruption
This function is concerned with the long-term CPU mask, not the transitory mask the task might have while migrate disabled. Before this patch, if a task was migrate-disabled at the time __set_cpus_allowed_ptr() was called, and the new mask happened to be equal to the CPU that the task was running on, then the mask update would be lost. Signed-off-by: Scott Wood <swood@redhat.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200617121742.cpxppyi7twxmpin7@linutronix.de |
||
Kirill Tkhai
|
aa93cd53bc |
sched: Micro optimization in pick_next_task() and in check_preempt_curr()
This introduces an optimization based on xxx_sched_class addresses
in two hot scheduler functions: pick_next_task() and check_preempt_curr().
It is possible to compare pointers to sched classes to check, which
of them has a higher priority, instead of current iterations using
for_each_class().
One more result of the patch is that size of object file becomes a little
less (excluding added BUG_ON(), which goes in __init section):
$size kernel/sched/core.o
text data bss dec hex filename
before: 66446 18957 676 86079 1503f kernel/sched/core.o
after: 66398 18957 676 86031 1500f kernel/sched/core.o
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/711a9c4b-ff32-1136-b848-17c622d548f3@yandex.ru
|
||
Steven Rostedt (VMware)
|
c3a340f7e7 |
sched: Have sched_class_highest define by vmlinux.lds.h
Now that the sched_class descriptors are defined by the linker script, and this needs to be aware of the existance of stop_sched_class when SMP is enabled or not, as it is used as the "highest" priority when defined. Move the declaration of sched_class_highest to the same location in the linker script that inserts stop_sched_class, and this will also make it easier to see what should be defined as the highest class, as this linker script location defines the priorities as well. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20191219214558.682913590@goodmis.org |
||
|
Peter Zijlstra
|
8b700983de |
sched: Remove sched_set_*() return value
Ingo suggested that since the new sched_set_*() functions are implemented using the 'nocheck' variants, they really shouldn't ever fail, so remove the return value. Cc: axboe@kernel.dk Cc: daniel.lezcano@linaro.org Cc: sudeep.holla@arm.com Cc: airlied@redhat.com Cc: broonie@kernel.org Cc: paulmck@kernel.org Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> |
||
|
Peter Zijlstra
|
616d91b68c |
sched: Remove sched_setscheduler*() EXPORTs
Now that nothing (modular) still uses sched_setscheduler(), remove the exports. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> |
||
|
Peter Zijlstra
|
7318d4cc14 |
sched: Provide sched_set_fifo()
SCHED_FIFO (or any static priority scheduler) is a broken scheduler model; it is fundamentally incapable of resource management, the one thing an OS is actually supposed to do. It is impossible to compose static priority workloads. One cannot take two well designed and functional static priority workloads and mash them together and still expect them to work. Therefore it doesn't make sense to expose the priority field; the kernel is fundamentally incapable of setting a sensible value, it needs systems knowledge that it doesn't have. Take away sched_setschedule() / sched_setattr() from modules and replace them with: - sched_set_fifo(p); create a FIFO task (at prio 50) - sched_set_fifo_low(p); create a task higher than NORMAL, which ends up being a FIFO task at prio 1. - sched_set_normal(p, nice); (re)set the task to normal This stops the proliferation of randomly chosen, and irrelevant, FIFO priorities that dont't really mean anything anyway. The system administrator/integrator, whoever has insight into the actual system design and requirements (userspace) can set-up appropriate priorities if and when needed. Cc: airlied@redhat.com Cc: alexander.deucher@amd.com Cc: awalls@md.metrocast.net Cc: axboe@kernel.dk Cc: broonie@kernel.org Cc: daniel.lezcano@linaro.org Cc: gregkh@linuxfoundation.org Cc: hannes@cmpxchg.org Cc: herbert@gondor.apana.org.au Cc: hverkuil@xs4all.nl Cc: john.stultz@linaro.org Cc: nico@fluxnic.net Cc: paulmck@kernel.org Cc: rafael.j.wysocki@intel.com Cc: rmk+kernel@arm.linux.org.uk Cc: sudeep.holla@arm.com Cc: tglx@linutronix.de Cc: ulf.hansson@linaro.org Cc: wim@linux-watchdog.org Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Tested-by: Paul E. McKenney <paulmck@kernel.org> |
||
|
Vincent Donnefort
|
4581bea8b4 |
sched/debug: Add new tracepoints to track util_est
The util_est signals are key elements for EAS task placement and frequency selection. Having tracepoints to track these signals enables load-tracking and schedutil testing and/or debugging by a toolkit. Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Link: https://lkml.kernel.org/r/1590597554-370150-1-git-send-email-vincent.donnefort@arm.com |
||
Dietmar Eggemann
|
0900acf2d8 |
sched/core: Remove redundant 'preempt' param from sched_class->yield_to_task()
Commit
|
||
Dmitry Safonov
|
9cb8f069de |
kernel: rename show_stack_loglvl() => show_stack()
Now the last users of show_stack() got converted to use an explicit log level, show_stack_loglvl() can drop it's redundant suffix and become once again well known show_stack(). Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200418201944.482088-51-dima@arista.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Dmitry Safonov
|
8ba09b1dc1 |
sched: print stack trace with KERN_INFO
Aligning with other messages printed in sched_show_task() - use KERN_INFO to print the backtrace. Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Ben Segall <bsegall@google.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Vincent Guittot <vincent.guittot@linaro.org> Link: http://lkml.kernel.org/r/20200418201944.482088-49-dima@arista.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Dmitry Safonov
|
2062a4e8ae |
kallsyms/printk: add loglvl to print_ip_sym()
Patch series "Add log level to show_stack()", v3. Add log level argument to show_stack(). Done in three stages: 1. Introducing show_stack_loglvl() for every architecture 2. Migrating old users with an explicit log level 3. Renaming show_stack_loglvl() into show_stack() Justification: - It's a design mistake to move a business-logic decision into platform realization detail. - I have currently two patches sets that would benefit from this work: Removing console_loglevel jumps in sysrq driver [1] Hung task warning before panic [2] - suggested by Tetsuo (but he probably didn't realise what it would involve). - While doing (1), (2) the backtraces were adjusted to headers and other messages for each situation - so there won't be a situation when the backtrace is printed, but the headers are missing because they have lesser log level (or the reverse). - As the result in (2) plays with console_loglevel for kdb are removed. The least important for upstream, but maybe still worth to note that every company I've worked in so far had an off-list patch to print backtrace with the needed log level (but only for the architecture they cared about). If you have other ideas how you will benefit from show_stack() with a log level - please, reply to this cover letter. See also discussion on v1: https://lore.kernel.org/linux-riscv/20191106083538.z5nlpuf64cigxigh@pathway.suse.cz/ This patch (of 50): print_ip_sym() needs to have a log level parameter to comply with other parts being printed. Otherwise, half of the expected backtrace would be printed and other may be missing with some logging level. The following callee(s) are using now the adjusted log level: - microblaze/unwind: the same level as headers & userspace unwind. Note that pr_debug()'s there are for debugging the unwinder itself. - nds32/traps: symbol addresses are printed with the same log level as backtrace headers. - lockdep: ip for locking issues is printed with the same log level as other part of the warning. - sched: ip where preemption was disabled is printed as error like the rest part of the message. - ftrace: bug reports are now consistent in the log level being used. Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Ben Segall <bsegall@google.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Hogan <jhogan@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Burton <paulburton@kernel.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Will Deacon <will@kernel.org> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Dmitry Safonov <dima@arista.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Aurelien Jacquiot <jacquiot.aurelien@gmail.com> Cc: Mark Salter <msalter@redhat.com> Cc: Guo Ren <guoren@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Brian Cain <bcain@codeaurora.org> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ley Foon Tan <lftan@altera.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Stafford Horne <shorne@gmail.com> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Mackerras <paulus@samba.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Rich Felker <dalias@libc.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Chris Zankel <chris@zankel.net> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Len Brown <len.brown@intel.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: Douglas Anderson <dianders@chromium.org> Cc: Jason Wessel <jason.wessel@windriver.com> Link: http://lkml.kernel.org/r/20200418201944.482088-2-dima@arista.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Linus Torvalds
|
cb8e59cc87 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from David Miller:
1) Allow setting bluetooth L2CAP modes via socket option, from Luiz
Augusto von Dentz.
2) Add GSO partial support to igc, from Sasha Neftin.
3) Several cleanups and improvements to r8169 from Heiner Kallweit.
4) Add IF_OPER_TESTING link state and use it when ethtool triggers a
device self-test. From Andrew Lunn.
5) Start moving away from custom driver versions, use the globally
defined kernel version instead, from Leon Romanovsky.
6) Support GRO vis gro_cells in DSA layer, from Alexander Lobakin.
7) Allow hard IRQ deferral during NAPI, from Eric Dumazet.
8) Add sriov and vf support to hinic, from Luo bin.
9) Support Media Redundancy Protocol (MRP) in the bridging code, from
Horatiu Vultur.
10) Support netmap in the nft_nat code, from Pablo Neira Ayuso.
11) Allow UDPv6 encapsulation of ESP in the ipsec code, from Sabrina
Dubroca. Also add ipv6 support for espintcp.
12) Lots of ReST conversions of the networking documentation, from Mauro
Carvalho Chehab.
13) Support configuration of ethtool rxnfc flows in bcmgenet driver,
from Doug Berger.
14) Allow to dump cgroup id and filter by it in inet_diag code, from
Dmitry Yakunin.
15) Add infrastructure to export netlink attribute policies to
userspace, from Johannes Berg.
16) Several optimizations to sch_fq scheduler, from Eric Dumazet.
17) Fallback to the default qdisc if qdisc init fails because otherwise
a packet scheduler init failure will make a device inoperative. From
Jesper Dangaard Brouer.
18) Several RISCV bpf jit optimizations, from Luke Nelson.
19) Correct the return type of the ->ndo_start_xmit() method in several
drivers, it's netdev_tx_t but many drivers were using
'int'. From Yunjian Wang.
20) Add an ethtool interface for PHY master/slave config, from Oleksij
Rempel.
21) Add BPF iterators, from Yonghang Song.
22) Add cable test infrastructure, including ethool interfaces, from
Andrew Lunn. Marvell PHY driver is the first to support this
facility.
23) Remove zero-length arrays all over, from Gustavo A. R. Silva.
24) Calculate and maintain an explicit frame size in XDP, from Jesper
Dangaard Brouer.
25) Add CAP_BPF, from Alexei Starovoitov.
26) Support terse dumps in the packet scheduler, from Vlad Buslov.
27) Support XDP_TX bulking in dpaa2 driver, from Ioana Ciornei.
28) Add devm_register_netdev(), from Bartosz Golaszewski.
29) Minimize qdisc resets, from Cong Wang.
30) Get rid of kernel_getsockopt and kernel_setsockopt in order to
eliminate set_fs/get_fs calls. From Christoph Hellwig.
* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2517 commits)
selftests: net: ip_defrag: ignore EPERM
net_failover: fixed rollback in net_failover_open()
Revert "tipc: Fix potential tipc_aead refcnt leak in tipc_crypto_rcv"
Revert "tipc: Fix potential tipc_node refcnt leak in tipc_rcv"
vmxnet3: allow rx flow hash ops only when rss is enabled
hinic: add set_channels ethtool_ops support
selftests/bpf: Add a default $(CXX) value
tools/bpf: Don't use $(COMPILE.c)
bpf, selftests: Use bpf_probe_read_kernel
s390/bpf: Use bcr 0,%0 as tail call nop filler
s390/bpf: Maintain 8-byte stack alignment
selftests/bpf: Fix verifier test
selftests/bpf: Fix sample_cnt shared between two threads
bpf, selftests: Adapt cls_redirect to call csum_level helper
bpf: Add csum_level helper for fixing up csum levels
bpf: Fix up bpf_skb_adjust_room helper's skb csum setting
sfc: add missing annotation for efx_ef10_try_update_nic_stats_vf()
crypto/chtls: IPv6 support for inline TLS
Crypto/chcr: Fixes a coccinile check error
Crypto/chcr: Fixes compilations warnings
...
|
||
|
Linus Torvalds
|
d479c5a191 |
The changes in this cycle are:
- Optimize the task wakeup CPU selection logic, to improve scalability and
reduce wakeup latency spikes
- PELT enhancements
- CFS bandwidth handling fixes
- Optimize the wakeup path by remove rq->wake_list and replacing it with ->ttwu_pending
- Optimize IPI cross-calls by making flush_smp_call_function_queue()
process sync callbacks first.
- Misc fixes and enhancements.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-----BEGIN PGP SIGNATURE-----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=C2OP
-----END PGP SIGNATURE-----
Merge tag 'sched-core-2020-06-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"The changes in this cycle are:
- Optimize the task wakeup CPU selection logic, to improve
scalability and reduce wakeup latency spikes
- PELT enhancements
- CFS bandwidth handling fixes
- Optimize the wakeup path by remove rq->wake_list and replacing it
with ->ttwu_pending
- Optimize IPI cross-calls by making flush_smp_call_function_queue()
process sync callbacks first.
- Misc fixes and enhancements"
* tag 'sched-core-2020-06-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
irq_work: Define irq_work_single() on !CONFIG_IRQ_WORK too
sched/headers: Split out open-coded prototypes into kernel/sched/smp.h
sched: Replace rq::wake_list
sched: Add rq::ttwu_pending
irq_work, smp: Allow irq_work on call_single_queue
smp: Optimize send_call_function_single_ipi()
smp: Move irq_work_run() out of flush_smp_call_function_queue()
smp: Optimize flush_smp_call_function_queue()
sched: Fix smp_call_function_single_async() usage for ILB
sched/core: Offload wakee task activation if it the wakee is descheduling
sched/core: Optimize ttwu() spinning on p->on_cpu
sched: Defend cfs and rt bandwidth quota against overflow
sched/cpuacct: Fix charge cpuacct.usage_sys
sched/fair: Replace zero-length array with flexible-array
sched/pelt: Sync util/runnable_sum with PELT window when propagating
sched/cpuacct: Use __this_cpu_add() instead of this_cpu_ptr()
sched/fair: Optimize enqueue_task_fair()
sched: Make scheduler_ipi inline
sched: Clean up scheduler_ipi()
sched/core: Simplify sched_init()
...
|
||
|
Linus Torvalds
|
533b220f7b |
arm64 updates for 5.8
- Branch Target Identification (BTI)
* Support for ARMv8.5-BTI in both user- and kernel-space. This
allows branch targets to limit the types of branch from which
they can be called and additionally prevents branching to
arbitrary code, although kernel support requires a very recent
toolchain.
* Function annotation via SYM_FUNC_START() so that assembly
functions are wrapped with the relevant "landing pad"
instructions.
* BPF and vDSO updates to use the new instructions.
* Addition of a new HWCAP and exposure of BTI capability to
userspace via ID register emulation, along with ELF loader
support for the BTI feature in .note.gnu.property.
* Non-critical fixes to CFI unwind annotations in the sigreturn
trampoline.
- Shadow Call Stack (SCS)
* Support for Clang's Shadow Call Stack feature, which reserves
platform register x18 to point at a separate stack for each
task that holds only return addresses. This protects function
return control flow from buffer overruns on the main stack.
* Save/restore of x18 across problematic boundaries (user-mode,
hypervisor, EFI, suspend, etc).
* Core support for SCS, should other architectures want to use it
too.
* SCS overflow checking on context-switch as part of the existing
stack limit check if CONFIG_SCHED_STACK_END_CHECK=y.
- CPU feature detection
* Removed numerous "SANITY CHECK" errors when running on a system
with mismatched AArch32 support at EL1. This is primarily a
concern for KVM, which disabled support for 32-bit guests on
such a system.
* Addition of new ID registers and fields as the architecture has
been extended.
- Perf and PMU drivers
* Minor fixes and cleanups to system PMU drivers.
- Hardware errata
* Unify KVM workarounds for VHE and nVHE configurations.
* Sort vendor errata entries in Kconfig.
- Secure Monitor Call Calling Convention (SMCCC)
* Update to the latest specification from Arm (v1.2).
* Allow PSCI code to query the SMCCC version.
- Software Delegated Exception Interface (SDEI)
* Unexport a bunch of unused symbols.
* Minor fixes to handling of firmware data.
- Pointer authentication
* Add support for dumping the kernel PAC mask in vmcoreinfo so
that the stack can be unwound by tools such as kdump.
* Simplification of key initialisation during CPU bringup.
- BPF backend
* Improve immediate generation for logical and add/sub
instructions.
- vDSO
- Minor fixes to the linker flags for consistency with other
architectures and support for LLVM's unwinder.
- Clean up logic to initialise and map the vDSO into userspace.
- ACPI
- Work around for an ambiguity in the IORT specification relating
to the "num_ids" field.
- Support _DMA method for all named components rather than only
PCIe root complexes.
- Minor other IORT-related fixes.
- Miscellaneous
* Initialise debug traps early for KGDB and fix KDB cacheflushing
deadlock.
* Minor tweaks to early boot state (documentation update, set
TEXT_OFFSET to 0x0, increase alignment of PE/COFF sections).
* Refactoring and cleanup
-----BEGIN PGP SIGNATURE-----
iQFEBAABCgAuFiEEPxTL6PPUbjXGY88ct6xw3ITBYzQFAl7U9csQHHdpbGxAa2Vy
bmVsLm9yZwAKCRC3rHDchMFjNLBHCACs/YU4SM7Om5f+7QnxIKao5DBr2CnGGvdC
yTfDghFDTLQVv3MufLlfno3yBe5G8sQpcZfcc+hewfcGoMzVZXu8s7LzH6VSn9T9
jmT3KjDMrg0RjSHzyumJp2McyelTk0a4FiKArSIIKsJSXUyb1uPSgm7SvKVDwEwU
JGDzL9IGilmq59GiXfDzGhTZgmC37QdwRoRxDuqtqWQe5CHoRXYexg87HwBKOQxx
HgU9L7ehri4MRZfpyjaDrr6quJo3TVnAAKXNBh3mZAskVS9ZrfKpEH0kYWYuqybv
znKyHRecl/rrGePV8RTMtrwnSdU26zMXE/omsVVauDfG9hqzqm+Q
=w3qi
-----END PGP SIGNATURE-----
Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon:
"A sizeable pile of arm64 updates for 5.8.
Summary below, but the big two features are support for Branch Target
Identification and Clang's Shadow Call stack. The latter is currently
arm64-only, but the high-level parts are all in core code so it could
easily be adopted by other architectures pending toolchain support
Branch Target Identification (BTI):
- Support for ARMv8.5-BTI in both user- and kernel-space. This allows
branch targets to limit the types of branch from which they can be
called and additionally prevents branching to arbitrary code,
although kernel support requires a very recent toolchain.
- Function annotation via SYM_FUNC_START() so that assembly functions
are wrapped with the relevant "landing pad" instructions.
- BPF and vDSO updates to use the new instructions.
- Addition of a new HWCAP and exposure of BTI capability to userspace
via ID register emulation, along with ELF loader support for the
BTI feature in .note.gnu.property.
- Non-critical fixes to CFI unwind annotations in the sigreturn
trampoline.
Shadow Call Stack (SCS):
- Support for Clang's Shadow Call Stack feature, which reserves
platform register x18 to point at a separate stack for each task
that holds only return addresses. This protects function return
control flow from buffer overruns on the main stack.
- Save/restore of x18 across problematic boundaries (user-mode,
hypervisor, EFI, suspend, etc).
- Core support for SCS, should other architectures want to use it
too.
- SCS overflow checking on context-switch as part of the existing
stack limit check if CONFIG_SCHED_STACK_END_CHECK=y.
CPU feature detection:
- Removed numerous "SANITY CHECK" errors when running on a system
with mismatched AArch32 support at EL1. This is primarily a concern
for KVM, which disabled support for 32-bit guests on such a system.
- Addition of new ID registers and fields as the architecture has
been extended.
Perf and PMU drivers:
- Minor fixes and cleanups to system PMU drivers.
Hardware errata:
- Unify KVM workarounds for VHE and nVHE configurations.
- Sort vendor errata entries in Kconfig.
Secure Monitor Call Calling Convention (SMCCC):
- Update to the latest specification from Arm (v1.2).
- Allow PSCI code to query the SMCCC version.
Software Delegated Exception Interface (SDEI):
- Unexport a bunch of unused symbols.
- Minor fixes to handling of firmware data.
Pointer authentication:
- Add support for dumping the kernel PAC mask in vmcoreinfo so that
the stack can be unwound by tools such as kdump.
- Simplification of key initialisation during CPU bringup.
BPF backend:
- Improve immediate generation for logical and add/sub instructions.
vDSO:
- Minor fixes to the linker flags for consistency with other
architectures and support for LLVM's unwinder.
- Clean up logic to initialise and map the vDSO into userspace.
ACPI:
- Work around for an ambiguity in the IORT specification relating to
the "num_ids" field.
- Support _DMA method for all named components rather than only PCIe
root complexes.
- Minor other IORT-related fixes.
Miscellaneous:
- Initialise debug traps early for KGDB and fix KDB cacheflushing
deadlock.
- Minor tweaks to early boot state (documentation update, set
TEXT_OFFSET to 0x0, increase alignment of PE/COFF sections).
- Refactoring and cleanup"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (148 commits)
KVM: arm64: Move __load_guest_stage2 to kvm_mmu.h
KVM: arm64: Check advertised Stage-2 page size capability
arm64/cpufeature: Add get_arm64_ftr_reg_nowarn()
ACPI/IORT: Remove the unused __get_pci_rid()
arm64/cpuinfo: Add ID_MMFR4_EL1 into the cpuinfo_arm64 context
arm64/cpufeature: Add remaining feature bits in ID_AA64PFR1 register
arm64/cpufeature: Add remaining feature bits in ID_AA64PFR0 register
arm64/cpufeature: Add remaining feature bits in ID_AA64ISAR0 register
arm64/cpufeature: Add remaining feature bits in ID_MMFR4 register
arm64/cpufeature: Add remaining feature bits in ID_PFR0 register
arm64/cpufeature: Introduce ID_MMFR5 CPU register
arm64/cpufeature: Introduce ID_DFR1 CPU register
arm64/cpufeature: Introduce ID_PFR2 CPU register
arm64/cpufeature: Make doublelock a signed feature in ID_AA64DFR0
arm64/cpufeature: Drop TraceFilt feature exposure from ID_DFR0 register
arm64/cpufeature: Add explicit ftr_id_isar0[] for ID_ISAR0 register
arm64: mm: Add asid_gen_match() helper
firmware: smccc: Fix missing prototype warning for arm_smccc_version_init
arm64: vdso: Fix CFI directives in sigreturn trampoline
arm64: vdso: Don't prefix sigreturn trampoline with a BTI C instruction
...
|
||
Ingo Molnar
|
1f8db41505 |
sched/headers: Split out open-coded prototypes into kernel/sched/smp.h
Move the prototypes for sched_ttwu_pending() and send_call_function_single_ipi() into the newly created kernel/sched/smp.h header, to make sure they are all the same, and to architectures happy that use -Wmissing-prototypes. Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Peter Zijlstra
|
a148866489 |
sched: Replace rq::wake_list
The recent commit:
|
||
|
Peter Zijlstra
|
126c2092e5 |
sched: Add rq::ttwu_pending
In preparation of removing rq->wake_list, replace the !list_empty(rq->wake_list) with rq->ttwu_pending. This is not fully equivalent as this new variable is racy. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200526161908.070399698@infradead.org |
||
|
Peter Zijlstra
|
b2a02fc43a |
smp: Optimize send_call_function_single_ipi()
Just like the ttwu_queue_remote() IPI, make use of _TIF_POLLING_NRFLAG to avoid sending IPIs to idle CPUs. [ mingo: Fix UP build bug. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200526161907.953304789@infradead.org |
||
|
Peter Zijlstra
|
19a1f5ec69 |
sched: Fix smp_call_function_single_async() usage for ILB
The recent commit: |
||
|
Ingo Molnar
|
58ef57b16d |
Merge branch 'core/rcu' into sched/core, to pick up dependency
We are going to rely on the loosening of RCU callback semantics,
introduced by this commit:
|
||
Mel Gorman
|
2ebb177175 |
sched/core: Offload wakee task activation if it the wakee is descheduling
The previous commit:
|
||
|
Peter Zijlstra
|
c6e7bd7afa |
sched/core: Optimize ttwu() spinning on p->on_cpu
Both Rik and Mel reported seeing ttwu() spend significant time on: smp_cond_load_acquire(&p->on_cpu, !VAL); Attempt to avoid this by queueing the wakeup on the CPU that owns the p->on_cpu value. This will then allow the ttwu() to complete without further waiting. Since we run schedule() with interrupts disabled, the IPI is guaranteed to happen after p->on_cpu is cleared, this is what makes it safe to queue early. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Jirka Hladky <jhladky@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: valentin.schneider@arm.com Cc: Hillf Danton <hdanton@sina.com> Cc: Rik van Riel <riel@surriel.com> Link: https://lore.kernel.org/r/20200524202956.27665-2-mgorman@techsingularity.net |
||
Huaixin Chang
|
d505b8af58 |
sched: Defend cfs and rt bandwidth quota against overflow
When users write some huge number into cpu.cfs_quota_us or cpu.rt_runtime_us, overflow might happen during to_ratio() shifts of schedulable checks. to_ratio() could be altered to avoid unnecessary internal overflow, but min_cfs_quota_period is less than 1 << BW_SHIFT, so a cutoff would still be needed. Set a cap MAX_BW for cfs_quota_us and rt_runtime_us to prevent overflow. Signed-off-by: Huaixin Chang <changhuaixin@linux.alibaba.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ben Segall <bsegall@google.com> Link: https://lkml.kernel.org/r/20200425105248.60093-1-changhuaixin@linux.alibaba.com |
||
|
Thomas Gleixner
|
1ed0948eea |
Merge tag 'noinstr-lds-2020-05-19' into core/rcu
Get the noinstr section and annotation markers to base the RCU parts on. |
||
Will Deacon
|
88485be531 |
scs: Move scs_overflow_check() out of architecture code
There is nothing architecture-specific about scs_overflow_check() as it's just a trivial wrapper around scs_corrupted(). For parity with task_stack_end_corrupted(), rename scs_corrupted() to task_scs_end_corrupted() and call it from schedule_debug() when CONFIG_SCHED_STACK_END_CHECK_is enabled, which better reflects its purpose as a debug feature to catch inadvertent overflow of the SCS. Finally, remove the unused scs_overflow_check() function entirely. This has absolutely no impact on architectures that do not support SCS (currently arm64 only). Tested-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will@kernel.org> |
||
Sami Tolvanen
|
d08b9f0ca6 |
scs: Add support for Clang's Shadow Call Stack (SCS)
This change adds generic support for Clang's Shadow Call Stack, which uses a shadow stack to protect return addresses from being overwritten by an attacker. Details are available here: https://clang.llvm.org/docs/ShadowCallStack.html Note that security guarantees in the kernel differ from the ones documented for user space. The kernel must store addresses of shadow stacks in memory, which means an attacker capable reading and writing arbitrary memory may be able to locate them and hijack control flow by modifying the stacks. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> [will: Numerous cosmetic changes] Signed-off-by: Will Deacon <will@kernel.org> |
||
|
Thomas Gleixner
|
2a0a24ebb4 |
sched: Make scheduler_ipi inline
Now that the scheduler IPI is trivial and simple again there is no point to have the little function out of line. This simplifies the effort of constraining the instrumentation nicely. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200505134058.453581595@linutronix.de |
||
|
Peter Zijlstra (Intel)
|
90b5363acd |
sched: Clean up scheduler_ipi()
The scheduler IPI has grown weird and wonderful over the years, time for spring cleaning. Move all the non-trivial stuff out of it and into a regular smp function call IPI. This then reduces the schedule_ipi() to most of it's former NOP glory and ensures to keep the interrupt vector lean and mean. Aside of that avoiding the full irq_enter() in the x86 IPI implementation is incorrect as scheduler_ipi() can be instrumented. To work around that scheduler_ipi() had an irq_enter/exit() hack when heavy work was pending. This is gone now. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Link: https://lkml.kernel.org/r/20200505134058.361859938@linutronix.de |
||
Wei Yang
|
b1d1779e5e |
sched/core: Simplify sched_init()
Currently root_task_group.shares and cfs_bandwidth are initialized for each online cpu, which not necessary. Let's take it out to do it only once. Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200423214443.29994-1-richard.weiyang@gmail.com |
||
|
Peter Zijlstra
|
bf2c59fce4 |
sched/core: Fix illegal RCU from offline CPUs
In the CPU-offline process, it calls mmdrop() after idle entry and the subsequent call to cpuhp_report_idle_dead(). Once execution passes the call to rcu_report_dead(), RCU is ignoring the CPU, which results in lockdep complaining when mmdrop() uses RCU from either memcg or debugobjects below. Fix it by cleaning up the active_mm state from BP instead. Every arch which has CONFIG_HOTPLUG_CPU should have already called idle_task_exit() from AP. The only exception is parisc because it switches them to &init_mm unconditionally (see smp_boot_one_cpu() and smp_cpu_init()), but the patch will still work there because it calls mmgrab(&init_mm) in smp_cpu_init() and then should call mmdrop(&init_mm) in finish_cpu(). WARNING: suspicious RCU usage ----------------------------- kernel/workqueue.c:710 RCU or wq_pool_mutex should be held! other info that might help us debug this: RCU used illegally from offline CPU! Call Trace: dump_stack+0xf4/0x164 (unreliable) lockdep_rcu_suspicious+0x140/0x164 get_work_pool+0x110/0x150 __queue_work+0x1bc/0xca0 queue_work_on+0x114/0x120 css_release+0x9c/0xc0 percpu_ref_put_many+0x204/0x230 free_pcp_prepare+0x264/0x570 free_unref_page+0x38/0xf0 __mmdrop+0x21c/0x2c0 idle_task_exit+0x170/0x1b0 pnv_smp_cpu_kill_self+0x38/0x2e0 cpu_die+0x48/0x64 arch_cpu_idle_dead+0x30/0x50 do_idle+0x2f4/0x470 cpu_startup_entry+0x38/0x40 start_secondary+0x7a8/0xa80 start_secondary_resume+0x10/0x14 Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Link: https://lkml.kernel.org/r/20200401214033.8448-1-cai@lca.pw |
||
Chen Yu
|
457d1f4657 |
sched: Extract the task putting code from pick_next_task()
Introduce a new function put_prev_task_balance() to do the balance when necessary, and then put previous task back to the run queue. This function is extracted from pick_next_task() to prepare for future usage by other type of task picking logic. No functional change. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Chen Yu <yu.c.chen@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Link: https://lkml.kernel.org/r/5a99860cf66293db58a397d6248bcb2eee326776.1587464698.git.yu.c.chen@intel.com |
||
Daniel Borkmann
|
0b54142e4b |
Merge branch 'work.sysctl' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull in Christoph Hellwig's series that changes the sysctl's ->proc_handler methods to take kernel pointers instead. It gets rid of the set_fs address space overrides used by BPF. As per discussion, pull in the feature branch into bpf-next as it relates to BPF sysctl progs. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200427071508.GV23230@ZenIV.linux.org.uk/T/ |
||
Paul E. McKenney
|
2beaf3280e |
sched/core: Add function to sample state of locked-down task
A running task's state can be sampled in a consistent manner (for example, for diagnostic purposes) simply by invoking smp_call_function_single() on its CPU, which may be obtained using task_cpu(), then having the IPI handler verify that the desired task is in fact still running. However, if the task is not running, this sampling can in theory be done immediately and directly. In practice, the task might start running at any time, including during the sampling period. Gaining a consistent sample of a not-running task therefore requires that something be done to lock down the target task's state. This commit therefore adds a try_invoke_on_locked_down_task() function that invokes a specified function if the specified task can be locked down, returning true if successful and if the specified function returns true. Otherwise this function simply returns false. Given that the function passed to try_invoke_on_nonrunning_task() might be invoked with a runqueue lock held, that function had better be quite lightweight. The function is passed the target task's task_struct pointer and the argument passed to try_invoke_on_locked_down_task(), allowing easy access to task state and to a location for further variables to be passed in and out. Note that the specified function will be called even if the specified task is currently running. The function can use ->on_rq and task_curr() to quickly and easily determine the task's state, and can return false if this state is not to the function's liking. The caller of the try_invoke_on_locked_down_task() would then see the false return value, and could take appropriate action, for example, trying again later or sending an IPI if matters are more urgent. It is expected that use cases such as the RCU CPU stall warning code will simply return false if the task is currently running. However, there are use cases involving nohz_full CPUs where the specified function might instead fall back to an alternative sampling scheme that relies on heavier synchronization (such as memory barriers) in the target task. Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Ben Segall <bsegall@google.com> Cc: Mel Gorman <mgorman@suse.de> [ paulmck: Apply feedback from Peter Zijlstra and Steven Rostedt. ] [ paulmck: Invoke if running to handle feedback from Mathieu Desnoyers. ] Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> |
||
Christoph Hellwig
|
32927393dc |
sysctl: pass kernel pointers to ->proc_handler
Instead of having all the sysctl handlers deal with user pointers, which is rather hairy in terms of the BPF interaction, copy the input to and from userspace in common code. This also means that the strings are always NUL-terminated by the common code, making the API a little bit safer. As most handler just pass through the data to one of the common handlers a lot of the changes are mechnical. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
||
Quentin Perret
|
eaf5a92ebd |
sched/core: Fix reset-on-fork from RT with uclamp
uclamp_fork() resets the uclamp values to their default when the
reset-on-fork flag is set. It also checks whether the task has a RT
policy, and sets its uclamp.min to 1024 accordingly. However, during
reset-on-fork, the task's policy is lowered to SCHED_NORMAL right after,
hence leading to an erroneous uclamp.min setting for the new task if it
was forked from RT.
Fix this by removing the unnecessary check on rt_task() in
uclamp_fork() as this doesn't make sense if the reset-on-fork flag is
set.
Fixes:
|
||
|
Vincent Donnefort
|
275b2f6723 |
sched/core: Remove unused rq::last_load_update_tick
The following commit:
|
||
|
Sebastian Andrzej Siewior
|
62849a9612 |
workqueue: Remove the warning in wq_worker_sleeping()
The kernel test robot triggered a warning with the following race:
task-ctx A interrupt-ctx B
worker
-> process_one_work()
-> work_item()
-> schedule();
-> sched_submit_work()
-> wq_worker_sleeping()
-> ->sleeping = 1
atomic_dec_and_test(nr_running)
__schedule(); *interrupt*
async_page_fault()
-> local_irq_enable();
-> schedule();
-> sched_submit_work()
-> wq_worker_sleeping()
-> if (WARN_ON(->sleeping)) return
-> __schedule()
-> sched_update_worker()
-> wq_worker_running()
-> atomic_inc(nr_running);
-> ->sleeping = 0;
-> sched_update_worker()
-> wq_worker_running()
if (!->sleeping) return
In this context the warning is pointless everything is fine.
An interrupt before wq_worker_sleeping() will perform the ->sleeping
assignment (0 -> 1 > 0) twice.
An interrupt after wq_worker_sleeping() will trigger the warning and
nr_running will be decremented (by A) and incremented once (only by B, A
will skip it). This is the case until the ->sleeping is zeroed again in
wq_worker_running().
Remove the WARN statement because this condition may happen. Document
that preemption around wq_worker_sleeping() needs to be disabled to
protect ->sleeping and not just as an optimisation.
Fixes:
|
||
|
Valentin Schneider
|
d76343c6b2 |
sched/fair: Align rq->avg_idle and rq->avg_scan_cost
sched/core.c uses update_avg() for rq->avg_idle and sched/fair.c uses an
open-coded version (with the exact same decay factor) for
rq->avg_scan_cost. On top of that, select_idle_cpu() expects to be able to
compare these two fields.
The only difference between the two is that rq->avg_scan_cost is computed
using a pure division rather than a shift. Turns out it actually matters,
first of all because the shifted value can be negative, and the standard
has this to say about it:
"""
The result of E1 >> E2 is E1 right-shifted E2 bit positions. [...] If E1
has a signed type and a negative value, the resulting value is
implementation-defined.
"""
Not only this, but (arithmetic) right shifting a negative value (using 2's
complement) is *not* equivalent to dividing it by the corresponding power
of 2. Let's look at a few examples:
-4 -> 0xF..FC
-4 >> 3 -> 0xF..FF == -1 != -4 / 8
-8 -> 0xF..F8
-8 >> 3 -> 0xF..FF == -1 == -8 / 8
-9 -> 0xF..F7
-9 >> 3 -> 0xF..FE == -2 != -9 / 8
Make update_avg() use a division, and export it to the private scheduler
header to reuse it where relevant. Note that this still lets compilers use
a shift here, but should prevent any unwanted surprise. The disassembly of
select_idle_cpu() remains unchanged on arm64, and ttwu_do_wakeup() gains 2
instructions; the diff sort of looks like this:
- sub x1, x1, x0
+ subs x1, x1, x0 // set condition codes
+ add x0, x1, #0x7
+ csel x0, x0, x1, mi // x0 = x1 < 0 ? x0 : x1
add x0, x3, x0, asr #3
which does the right thing (i.e. gives us the expected result while still
using an arithmetic shift)
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200330090127.16294-1-valentin.schneider@arm.com
|
||
|
Linus Torvalds
|
992a1a3b45 |
CPU (hotplug) updates:
- Support for locked CSD objects in smp_call_function_single_async()
which allows to simplify callsites in the scheduler core and MIPS
- Treewide consolidation of CPU hotplug functions which ensures the
consistency between the sysfs interface and kernel state. The low level
functions cpu_up/down() are now confined to the core code and not
longer accessible from random code.
-----BEGIN PGP SIGNATURE-----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=jwCg
-----END PGP SIGNATURE-----
Merge tag 'smp-core-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core SMP updates from Thomas Gleixner:
"CPU (hotplug) updates:
- Support for locked CSD objects in smp_call_function_single_async()
which allows to simplify callsites in the scheduler core and MIPS
- Treewide consolidation of CPU hotplug functions which ensures the
consistency between the sysfs interface and kernel state. The low
level functions cpu_up/down() are now confined to the core code and
not longer accessible from random code"
* tag 'smp-core-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
cpu/hotplug: Ignore pm_wakeup_pending() for disable_nonboot_cpus()
cpu/hotplug: Hide cpu_up/down()
cpu/hotplug: Move bringup of secondary CPUs out of smp_init()
torture: Replace cpu_up/down() with add/remove_cpu()
firmware: psci: Replace cpu_up/down() with add/remove_cpu()
xen/cpuhotplug: Replace cpu_up/down() with device_online/offline()
parisc: Replace cpu_up/down() with add/remove_cpu()
sparc: Replace cpu_up/down() with add/remove_cpu()
powerpc: Replace cpu_up/down() with add/remove_cpu()
x86/smp: Replace cpu_up/down() with add/remove_cpu()
arm64: hibernate: Use bringup_hibernate_cpu()
cpu/hotplug: Provide bringup_hibernate_cpu()
arm64: Use reboot_cpu instead of hardconding it to 0
arm64: Don't use disable_nonboot_cpus()
ARM: Use reboot_cpu instead of hardcoding it to 0
ARM: Don't use disable_nonboot_cpus()
ia64: Replace cpu_down() with smp_shutdown_nonboot_cpus()
cpu/hotplug: Create a new function to shutdown nonboot cpus
cpu/hotplug: Add new {add,remove}_cpu() functions
sched/core: Remove rq.hrtick_csd_pending
...
|
||
Johannes Weiner
|
b05e75d611 |
psi: Fix cpu.pressure for cpu.max and competing cgroups
For simplicity, cpu pressure is defined as having more than one runnable task on a given CPU. This works on the system-level, but it has limitations in a cgrouped reality: When cpu.max is in use, it doesn't capture the time in which a task is not executing on the CPU due to throttling. Likewise, it doesn't capture the time in which a competing cgroup is occupying the CPU - meaning it only reflects cgroup-internal competitive pressure, not outside pressure. Enable tracking of currently executing tasks, and then change the definition of cpu pressure in a cgroup from NR_RUNNING > 1 to NR_RUNNING > ON_CPU which will capture the effects of cpu.max as well as competition from outside the cgroup. After this patch, a cgroup running `stress -c 1` with a cpu.max setting of 5000 10000 shows ~50% continuous CPU pressure. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200316191333.115523-2-hannes@cmpxchg.org |
||
Paul Turner
|
46a87b3851 |
sched/core: Distribute tasks within affinity masks
Currently, when updating the affinity of tasks via either cpusets.cpus,
or, sched_setaffinity(); tasks not currently running within the newly
specified mask will be arbitrarily assigned to the first CPU within the
mask.
This (particularly in the case that we are restricting masks) can
result in many tasks being assigned to the first CPUs of their new
masks.
This:
1) Can induce scheduling delays while the load-balancer has a chance to
spread them between their new CPUs.
2) Can antogonize a poor load-balancer behavior where it has a
difficult time recognizing that a cross-socket imbalance has been
forced by an affinity mask.
This change adds a new cpumask interface to allow iterated calls to
distribute within the intersection of the provided masks.
The cases that this mainly affects are:
- modifying cpuset.cpus
- when tasks join a cpuset
- when modifying a task's affinity via sched_setaffinity(2)
Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Qais Yousef <qais.yousef@arm.com>
Tested-by: Qais Yousef <qais.yousef@arm.com>
Link: https://lkml.kernel.org/r/20200311010113.136465-1-joshdon@google.com
|
||
|
Ingo Molnar
|
14533a16c4 |
thermal/cpu-cooling, sched/core: Move the arch_set_thermal_pressure() API to generic scheduler code
drivers/base/arch_topology.c is only built if CONFIG_GENERIC_ARCH_TOPOLOGY=y, resulting in such build failures: cpufreq_cooling.c:(.text+0x1e7): undefined reference to `arch_set_thermal_pressure' Move it to sched/core.c instead, and keep it enabled on x86 despite us not having a arch_scale_thermal_pressure() facility there, to build-test this thing. Cc: Thara Gopinath <thara.gopinath@linaro.org> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
Peter Xu
|
fd3eafda8f |
sched/core: Remove rq.hrtick_csd_pending
Now smp_call_function_single_async() provides the protection that we'll return with -EBUSY if the csd object is still pending, then we don't need the rq.hrtick_csd_pending any more. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20191216213125.9536-4-peterx@redhat.com |
||
Thara Gopinath
|
05289b90c2 |
sched/fair: Enable tuning of decay period
Thermal pressure follows pelt signals which means the decay period for thermal pressure is the default pelt decay period. Depending on SoC characteristics and thermal activity, it might be beneficial to decay thermal pressure slower, but still in-tune with the pelt signals. One way to achieve this is to provide a command line parameter to set a decay shift parameter to an integer between 0 and 10. Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200222005213.3873-10-thara.gopinath@linaro.org |
||
|
Thara Gopinath
|
b4eccf5f8e |
sched/fair: Enable periodic update of average thermal pressure
Introduce support in scheduler periodic tick and other CFS bookkeeping APIs to trigger the process of computing average thermal pressure for a CPU. Also consider avg_thermal.load_avg in others_have_blocked which allows for decay of pelt signals. Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200222005213.3873-7-thara.gopinath@linaro.org |
||
Vincent Guittot
|
0dacee1bfa |
sched/pelt: Remove unused runnable load average
Now that runnable_load_avg is no more used, we can remove it to make space for a new signal. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: "Dietmar Eggemann <dietmar.eggemann@arm.com>" Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Valentin Schneider <valentin.schneider@arm.com> Cc: Phil Auld <pauld@redhat.com> Cc: Hillf Danton <hdanton@sina.com> Link: https://lore.kernel.org/r/20200224095223.13361-8-mgorman@techsingularity.net |
||
|
Ingo Molnar
|
546121b65f |
Linux 5.6-rc3
-----BEGIN PGP SIGNATURE----- iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAl5TFjYeHHRvcnZhbGRz QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGikYIAIhI4C8R87wyj/0m b2NWk6TZ5AFmiZLYSbsPYxdSC9OLdUmlGFKgL2SyLTwZCiHChm+cNBrngp3hJ6gz x1YH99HdjzkiaLa0hCc2+a/aOt8azGU2RiWEP8rbo0gFSk28wE6FjtzSxR95jyPz FRKo/sM+dHBMFXrthJbr+xHZ1De28MITzS2ddstr/10ojoRgm43I3qo1JKhjoDN5 9GGb6v0Md5eo+XZjjB50CvgF5GhpiqW7+HBB7npMsgTk37GdsR5RlosJ/TScLVC9 dNeanuqk8bqMGM0u2DFYdDqjcqAlYbt8aobuWWCB5xgPBXr5G2nox+IgF/f9G6UH EShA/xs= =OFPc -----END PGP SIGNATURE----- Merge tag 'v5.6-rc3' into sched/core, to pick up fixes and dependent patches Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Scott Wood
|
82e0516ce3 |
sched/core: Remove duplicate assignment in sched_tick_remote()
A redundant "curr = rq->curr" was added; remove it.
Fixes:
|
||
|
Mel Gorman
|
52262ee567 |
sched/fair: Allow a per-CPU kthread waking a task to stack on the same CPU, to fix XFS performance regression
The following XFS commit:
|
||
Giovanni Gherdovich
|
1567c3e346 |
x86, sched: Add support for frequency invariance
Implement arch_scale_freq_capacity() for 'modern' x86. This function
is used by the scheduler to correctly account usage in the face of
DVFS.
The present patch addresses Intel processors specifically and has positive
performance and performance-per-watt implications for the schedutil cpufreq
governor, bringing it closer to, if not on-par with, the powersave governor
from the intel_pstate driver/framework.
Large performance gains are obtained when the machine is lightly loaded and
no regression are observed at saturation. The benchmarks with the largest
gains are kernel compilation, tbench (the networking version of dbench) and
shell-intensive workloads.
1. FREQUENCY INVARIANCE: MOTIVATION
* Without it, a task looks larger if the CPU runs slower
2. PECULIARITIES OF X86
* freq invariance accounting requires knowing the ratio freq_curr/freq_max
2.1 CURRENT FREQUENCY
* Use delta_APERF / delta_MPERF * freq_base (a.k.a "BusyMHz")
2.2 MAX FREQUENCY
* It varies with time (turbo). As an approximation, we set it to a
constant, i.e. 4-cores turbo frequency.
3. EFFECTS ON THE SCHEDUTIL FREQUENCY GOVERNOR
* The invariant schedutil's formula has no feedback loop and reacts faster
to utilization changes
4. KNOWN LIMITATIONS
* In some cases tasks can't reach max util despite how hard they try
5. PERFORMANCE TESTING
5.1 MACHINES
* Skylake, Broadwell, Haswell
5.2 SETUP
* baseline Linux v5.2 w/ non-invariant schedutil. Tested freq_max = 1-2-3-4-8-12
active cores turbo w/ invariant schedutil, and intel_pstate/powersave
5.3 BENCHMARK RESULTS
5.3.1 NEUTRAL BENCHMARKS
* NAS Parallel Benchmark (HPC), hackbench
5.3.2 NON-NEUTRAL BENCHMARKS
* tbench (10-30% better), kernbench (10-15% better),
shell-intensive-scripts (30-50% better)
* no regressions
5.3.3 SELECTION OF DETAILED RESULTS
5.3.4 POWER CONSUMPTION, PERFORMANCE-PER-WATT
* dbench (5% worse on one machine), kernbench (3% worse),
tbench (5-10% better), shell-intensive-scripts (10-40% better)
6. MICROARCH'ES ADDRESSED HERE
* Xeon Core before Scalable Performance processors line (Xeon Gold/Platinum
etc have different MSRs semantic for querying turbo levels)
7. REFERENCES
* MMTests performance testing framework, github.com/gormanm/mmtests
+-------------------------------------------------------------------------+
| 1. FREQUENCY INVARIANCE: MOTIVATION
+-------------------------------------------------------------------------+
For example; suppose a CPU has two frequencies: 500 and 1000 Mhz. When
running a task that would consume 1/3rd of a CPU at 1000 MHz, it would
appear to consume 2/3rd (or 66.6%) when running at 500 MHz, giving the
false impression this CPU is almost at capacity, even though it can go
faster [*]. In a nutshell, without frequency scale-invariance tasks look
larger just because the CPU is running slower.
[*] (footnote: this assumes a linear frequency/performance relation; which
everybody knows to be false, but given realities its the best approximation
we can make.)
+-------------------------------------------------------------------------+
| 2. PECULIARITIES OF X86
+-------------------------------------------------------------------------+
Accounting for frequency changes in PELT signals requires the computation of
the ratio freq_curr / freq_max. On x86 neither of those terms is readily
available.
2.1 CURRENT FREQUENCY
====================
Since modern x86 has hardware control over the actual frequency we run
at (because amongst other things, Turbo-Mode), we cannot simply use
the frequency as requested through cpufreq.
Instead we use the APERF/MPERF MSRs to compute the effective frequency
over the recent past. Also, because reading MSRs is expensive, don't
do so every time we need the value, but amortize the cost by doing it
every tick.
2.2 MAX FREQUENCY
=================
Obtaining freq_max is also non-trivial because at any time the hardware can
provide a frequency boost to a selected subset of cores if the package has
enough power to spare (eg: Turbo Boost). This means that the maximum frequency
available to a given core changes with time.
The approach taken in this change is to arbitrarily set freq_max to a constant
value at boot. The value chosen is the "4-cores (4C) turbo frequency" on most
microarchitectures, after evaluating the following candidates:
* 1-core (1C) turbo frequency (the fastest turbo state available)
* around base frequency (a.k.a. max P-state)
* something in between, such as 4C turbo
To interpret these options, consider that this is the denominator in
freq_curr/freq_max, and that ratio will be used to scale PELT signals such as
util_avg and load_avg. A large denominator will undershoot (util_avg looks a
bit smaller than it really is), viceversa with a smaller denominator PELT
signals will tend to overshoot. Given that PELT drives frequency selection
in the schedutil governor, we will have:
freq_max set to | effect on DVFS
--------------------+------------------
1C turbo | power efficiency (lower freq choices)
base freq | performance (higher util_avg, higher freq requests)
4C turbo | a bit of both
4C turbo proves to be a good compromise in a number of benchmarks (see below).
+-------------------------------------------------------------------------+
| 3. EFFECTS ON THE SCHEDUTIL FREQUENCY GOVERNOR
+-------------------------------------------------------------------------+
Once an architecture implements a frequency scale-invariant utilization (the
PELT signal util_avg), schedutil switches its frequency selection formula from
freq_next = 1.25 * freq_curr * util [non-invariant util signal]
to
freq_next = 1.25 * freq_max * util [invariant util signal]
where, in the second formula, freq_max is set to the 1C turbo frequency (max
turbo). The advantage of the second formula, whose usage we unlock with this
patch, is that freq_next doesn't depend on the current frequency in an
iterative fashion, but can jump to any frequency in a single update. This
absence of feedback in the formula makes it quicker to react to utilization
changes and more robust against pathological instabilities.
Compare it to the update formula of intel_pstate/powersave:
freq_next = 1.25 * freq_max * Busy%
where again freq_max is 1C turbo and Busy% is the percentage of time not spent
idling (calculated with delta_MPERF / delta_TSC); essentially the same as
invariant schedutil, and largely responsible for intel_pstate/powersave good
reputation. The non-invariant schedutil formula is derived from the invariant
one by approximating util_inv with util_raw * freq_curr / freq_max, but this
has limitations.
Testing shows improved performances due to better frequency selections when
the machine is lightly loaded, and essentially no change in behaviour at
saturation / overutilization.
+-------------------------------------------------------------------------+
| 4. KNOWN LIMITATIONS
+-------------------------------------------------------------------------+
It's been shown that it is possible to create pathological scenarios where a
CPU-bound task cannot reach max utilization, if the normalizing factor
freq_max is fixed to a constant value (see [Lelli-2018]).
If freq_max is set to 4C turbo as we do here, one needs to peg at least 5
cores in a package doing some busywork, and observe that none of those task
will ever reach max util (1024) because they're all running at less than the
4C turbo frequency.
While this concern still applies, we believe the performance benefit of
frequency scale-invariant PELT signals outweights the cost of this limitation.
[Lelli-2018]
https://lore.kernel.org/lkml/20180517150418.GF22493@localhost.localdomain/
+-------------------------------------------------------------------------+
| 5. PERFORMANCE TESTING
+-------------------------------------------------------------------------+
5.1 MACHINES
============
We tested the patch on three machines, with Skylake, Broadwell and Haswell
CPUs. The details are below, together with the available turbo ratios as
reported by the appropriate MSRs.
* 8x-SKYLAKE-UMA:
Single socket E3-1240 v5, Skylake 4 cores/8 threads
Max EFFiciency, BASE frequency and available turbo levels (MHz):
EFFIC 800 |********
BASE 3500 |***********************************
4C 3700 |*************************************
3C 3800 |**************************************
2C 3900 |***************************************
1C 3900 |***************************************
* 80x-BROADWELL-NUMA:
Two sockets E5-2698 v4, 2x Broadwell 20 cores/40 threads
Max EFFiciency, BASE frequency and available turbo levels (MHz):
EFFIC 1200 |************
BASE 2200 |**********************
8C 2900 |*****************************
7C 3000 |******************************
6C 3100 |*******************************
5C 3200 |********************************
4C 3300 |*********************************
3C 3400 |**********************************
2C 3600 |************************************
1C 3600 |************************************
* 48x-HASWELL-NUMA
Two sockets E5-2670 v3, 2x Haswell 12 cores/24 threads
Max EFFiciency, BASE frequency and available turbo levels (MHz):
EFFIC 1200 |************
BASE 2300 |***********************
12C 2600 |**************************
11C 2600 |**************************
10C 2600 |**************************
9C 2600 |**************************
8C 2600 |**************************
7C 2600 |**************************
6C 2600 |**************************
5C 2700 |***************************
4C 2800 |****************************
3C 2900 |*****************************
2C 3100 |*******************************
1C 3100 |*******************************
5.2 SETUP
=========
* The baseline is Linux v5.2 with schedutil (non-invariant) and the intel_pstate
driver in passive mode.
* The rationale for choosing the various freq_max values to test have been to
try all the 1-2-3-4C turbo levels (note that 1C and 2C turbo are identical
on all machines), plus one more value closer to base_freq but still in the
turbo range (8C turbo for both 80x-BROADWELL-NUMA and 48x-HASWELL-NUMA).
* In addition we've run all tests with intel_pstate/powersave for comparison.
* The filesystem is always XFS, the userspace is openSUSE Leap 15.1.
* 8x-SKYLAKE-UMA is capable of HWP (Hardware-Managed P-States), so the runs
with active intel_pstate on this machine use that.
This gives, in terms of combinations tested on each machine:
* 8x-SKYLAKE-UMA
* Baseline: Linux v5.2, non-invariant schedutil, intel_pstate passive
* intel_pstate active + powersave + HWP
* invariant schedutil, freq_max = 1C turbo
* invariant schedutil, freq_max = 3C turbo
* invariant schedutil, freq_max = 4C turbo
* both 80x-BROADWELL-NUMA and 48x-HASWELL-NUMA
* [same as 8x-SKYLAKE-UMA, but no HWP capable]
* invariant schedutil, freq_max = 8C turbo
(which on 48x-HASWELL-NUMA is the same as 12C turbo, or "all cores turbo")
5.3 BENCHMARK RESULTS
=====================
5.3.1 NEUTRAL BENCHMARKS
------------------------
Tests that didn't show any measurable difference in performance on any of the
test machines between non-invariant schedutil and our patch are:
* NAS Parallel Benchmarks (NPB) using either MPI or openMP for IPC, any
computational kernel
* flexible I/O (FIO)
* hackbench (using threads or processes, and using pipes or sockets)
5.3.2 NON-NEUTRAL BENCHMARKS
----------------------------
What follow are summary tables where each benchmark result is given a score.
* A tilde (~) means a neutral result, i.e. no difference from baseline.
* Scores are computed with the ratio result_new / result_baseline, so a tilde
means a score of 1.00.
* The results in the score ratio are the geometric means of results running
the benchmark with different parameters (eg: for kernbench: using 1, 2, 4,
... number of processes; for pgbench: varying the number of clients, and so
on).
* The first three tables show higher-is-better kind of tests (i.e. measured in
operations/second), the subsequent three show lower-is-better kind of tests
(i.e. the workload is fixed and we measure elapsed time, think kernbench).
* "gitsource" is a name we made up for the test consisting in running the
entire unit tests suite of the Git SCM and measuring how long it takes. We
take it as a typical example of shell-intensive serialized workload.
* In the "I_PSTATE" column we have the results for intel_pstate/powersave. Other
columns show invariant schedutil for different values of freq_max. 4C turbo
is circled as it's the value we've chosen for the final implementation.
80x-BROADWELL-NUMA (comparison ratio; higher is better)
+------+
I_PSTATE 1C 3C | 4C | 8C
pgbench-ro 1.14 ~ ~ | 1.11 | 1.14
pgbench-rw ~ ~ ~ | ~ | ~
netperf-udp 1.06 ~ 1.06 | 1.05 | 1.07
netperf-tcp ~ 1.03 ~ | 1.01 | 1.02
tbench4 1.57 1.18 1.22 | 1.30 | 1.56
+------+
8x-SKYLAKE-UMA (comparison ratio; higher is better)
+------+
I_PSTATE/HWP 1C 3C | 4C |
pgbench-ro ~ ~ ~ | ~ |
pgbench-rw ~ ~ ~ | ~ |
netperf-udp ~ ~ ~ | ~ |
netperf-tcp ~ ~ ~ | ~ |
tbench4 1.30 1.14 1.14 | 1.16 |
+------+
48x-HASWELL-NUMA (comparison ratio; higher is better)
+------+
I_PSTATE 1C 3C | 4C | 12C
pgbench-ro 1.15 ~ ~ | 1.06 | 1.16
pgbench-rw ~ ~ ~ | ~ | ~
netperf-udp 1.05 0.97 1.04 | 1.04 | 1.02
netperf-tcp 0.96 1.01 1.01 | 1.01 | 1.01
tbench4 1.50 1.05 1.13 | 1.13 | 1.25
+------+
In the table above we see that active intel_pstate is slightly better than our
4C-turbo patch (both in reference to the baseline non-invariant schedutil) on
read-only pgbench and much better on tbench. Both cases are notable in which
it shows that lowering our freq_max (to 8C-turbo and 12C-turbo on
80x-BROADWELL-NUMA and 48x-HASWELL-NUMA respectively) helps invariant
schedutil to get closer.
If we ignore active intel_pstate and focus on the comparison with baseline
alone, there are several instances of double-digit performance improvement.
80x-BROADWELL-NUMA (comparison ratio; lower is better)
+------+
I_PSTATE 1C 3C | 4C | 8C
dbench4 1.23 0.95 0.95 | 0.95 | 0.95
kernbench 0.93 0.83 0.83 | 0.83 | 0.82
gitsource 0.98 0.49 0.49 | 0.49 | 0.48
+------+
8x-SKYLAKE-UMA (comparison ratio; lower is better)
+------+
I_PSTATE/HWP 1C 3C | 4C |
dbench4 ~ ~ ~ | ~ |
kernbench ~ ~ ~ | ~ |
gitsource 0.92 0.55 0.55 | 0.55 |
+------+
48x-HASWELL-NUMA (comparison ratio; lower is better)
+------+
I_PSTATE 1C 3C | 4C | 8C
dbench4 ~ ~ ~ | ~ | ~
kernbench 0.94 0.90 0.89 | 0.90 | 0.90
gitsource 0.97 0.69 0.69 | 0.69 | 0.69
+------+
dbench is not very remarkable here, unless we notice how poorly active
intel_pstate is performing on 80x-BROADWELL-NUMA: 23% regression versus
non-invariant schedutil. We repeated that run getting consistent results. Out
of scope for the patch at hand, but deserving future investigation. Other than
that, we previously ran this campaign with Linux v5.0 and saw the patch doing
better on dbench a the time. We haven't checked closely and can only speculate
at this point.
On the NUMA boxes kernbench gets 10-15% improvements on average; we'll see in
the detailed tables that the gains concentrate on low process counts (lightly
loaded machines).
The test we call "gitsource" (running the git unit test suite, a long-running
single-threaded shell script) appears rather spectacular in this table (gains
of 30-50% depending on the machine). It is to be noted, however, that
gitsource has no adjustable parameters (such as the number of jobs in
kernbench, which we average over in order to get a single-number summary
score) and is exactly the kind of low-parallelism workload that benefits the
most from this patch. When looking at the detailed tables of kernbench or
tbench4, at low process or client counts one can see similar numbers.
5.3.3 SELECTION OF DETAILED RESULTS
-----------------------------------
Machine : 48x-HASWELL-NUMA
Benchmark : tbench4 (i.e. dbench4 over the network, actually loopback)
Varying parameter : number of clients
Unit : MB/sec (higher is better)
5.2.0 vanilla (BASELINE) 5.2.0 intel_pstate 5.2.0 1C-turbo
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Hmean 1 126.73 +- 0.31% ( ) 315.91 +- 0.66% ( 149.28%) 125.03 +- 0.76% ( -1.34%)
Hmean 2 258.04 +- 0.62% ( ) 614.16 +- 0.51% ( 138.01%) 269.58 +- 1.45% ( 4.47%)
Hmean 4 514.30 +- 0.67% ( ) 1146.58 +- 0.54% ( 122.94%) 533.84 +- 1.99% ( 3.80%)
Hmean 8 1111.38 +- 2.52% ( ) 2159.78 +- 0.38% ( 94.33%) 1359.92 +- 1.56% ( 22.36%)
Hmean 16 2286.47 +- 1.36% ( ) 3338.29 +- 0.21% ( 46.00%) 2720.20 +- 0.52% ( 18.97%)
Hmean 32 4704.84 +- 0.35% ( ) 4759.03 +- 0.43% ( 1.15%) 4774.48 +- 0.30% ( 1.48%)
Hmean 64 7578.04 +- 0.27% ( ) 7533.70 +- 0.43% ( -0.59%) 7462.17 +- 0.65% ( -1.53%)
Hmean 128 6998.52 +- 0.16% ( ) 6987.59 +- 0.12% ( -0.16%) 6909.17 +- 0.14% ( -1.28%)
Hmean 192 6901.35 +- 0.25% ( ) 6913.16 +- 0.10% ( 0.17%) 6855.47 +- 0.21% ( -0.66%)
5.2.0 3C-turbo 5.2.0 4C-turbo 5.2.0 12C-turbo
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Hmean 1 128.43 +- 0.28% ( 1.34%) 130.64 +- 3.81% ( 3.09%) 153.71 +- 5.89% ( 21.30%)
Hmean 2 311.70 +- 6.15% ( 20.79%) 281.66 +- 3.40% ( 9.15%) 305.08 +- 5.70% ( 18.23%)
Hmean 4 641.98 +- 2.32% ( 24.83%) 623.88 +- 5.28% ( 21.31%) 906.84 +- 4.65% ( 76.32%)
Hmean 8 1633.31 +- 1.56% ( 46.96%) 1714.16 +- 0.93% ( 54.24%) 2095.74 +- 0.47% ( 88.57%)
Hmean 16 3047.24 +- 0.42% ( 33.27%) 3155.02 +- 0.30% ( 37.99%) 3634.58 +- 0.15% ( 58.96%)
Hmean 32 4734.31 +- 0.60% ( 0.63%) 4804.38 +- 0.23% ( 2.12%) 4674.62 +- 0.27% ( -0.64%)
Hmean 64 7699.74 +- 0.35% ( 1.61%) 7499.72 +- 0.34% ( -1.03%) 7659.03 +- 0.25% ( 1.07%)
Hmean 128 6935.18 +- 0.15% ( -0.91%) 6942.54 +- 0.10% ( -0.80%) 7004.85 +- 0.12% ( 0.09%)
Hmean 192 6901.62 +- 0.12% ( 0.00%) 6856.93 +- 0.10% ( -0.64%) 6978.74 +- 0.10% ( 1.12%)
This is one of the cases where the patch still can't surpass active
intel_pstate, not even when freq_max is as low as 12C-turbo. Otherwise, gains are
visible up to 16 clients and the saturated scenario is the same as baseline.
The scores in the summary table from the previous sections are ratios of
geometric means of the results over different clients, as seen in this table.
Machine : 80x-BROADWELL-NUMA
Benchmark : kernbench (kernel compilation)
Varying parameter : number of jobs
Unit : seconds (lower is better)
5.2.0 vanilla (BASELINE) 5.2.0 intel_pstate 5.2.0 1C-turbo
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Amean 2 379.68 +- 0.06% ( ) 330.20 +- 0.43% ( 13.03%) 285.93 +- 0.07% ( 24.69%)
Amean 4 200.15 +- 0.24% ( ) 175.89 +- 0.22% ( 12.12%) 153.78 +- 0.25% ( 23.17%)
Amean 8 106.20 +- 0.31% ( ) 95.54 +- 0.23% ( 10.03%) 86.74 +- 0.10% ( 18.32%)
Amean 16 56.96 +- 1.31% ( ) 53.25 +- 1.22% ( 6.50%) 48.34 +- 1.73% ( 15.13%)
Amean 32 34.80 +- 2.46% ( ) 33.81 +- 0.77% ( 2.83%) 30.28 +- 1.59% ( 12.99%)
Amean 64 26.11 +- 1.63% ( ) 25.04 +- 1.07% ( 4.10%) 22.41 +- 2.37% ( 14.16%)
Amean 128 24.80 +- 1.36% ( ) 23.57 +- 1.23% ( 4.93%) 21.44 +- 1.37% ( 13.55%)
Amean 160 24.85 +- 0.56% ( ) 23.85 +- 1.17% ( 4.06%) 21.25 +- 1.12% ( 14.49%)
5.2.0 3C-turbo 5.2.0 4C-turbo 5.2.0 8C-turbo
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Amean 2 284.08 +- 0.13% ( 25.18%) 283.96 +- 0.51% ( 25.21%) 285.05 +- 0.21% ( 24.92%)
Amean 4 153.18 +- 0.22% ( 23.47%) 154.70 +- 1.64% ( 22.71%) 153.64 +- 0.30% ( 23.24%)
Amean 8 87.06 +- 0.28% ( 18.02%) 86.77 +- 0.46% ( 18.29%) 86.78 +- 0.22% ( 18.28%)
Amean 16 48.03 +- 0.93% ( 15.68%) 47.75 +- 1.99% ( 16.17%) 47.52 +- 1.61% ( 16.57%)
Amean 32 30.23 +- 1.20% ( 13.14%) 30.08 +- 1.67% ( 13.57%) 30.07 +- 1.67% ( 13.60%)
Amean 64 22.59 +- 2.02% ( 13.50%) 22.63 +- 0.81% ( 13.32%) 22.42 +- 0.76% ( 14.12%)
Amean 128 21.37 +- 0.67% ( 13.82%) 21.31 +- 1.15% ( 14.07%) 21.17 +- 1.93% ( 14.63%)
Amean 160 21.68 +- 0.57% ( 12.76%) 21.18 +- 1.74% ( 14.77%) 21.22 +- 1.00% ( 14.61%)
The patch outperform active intel_pstate (and baseline) by a considerable
margin; the summary table from the previous section says 4C turbo and active
intel_pstate are 0.83 and 0.93 against baseline respectively, so 4C turbo is
0.83/0.93=0.89 against intel_pstate (~10% better on average). There is no
noticeable difference with regard to the value of freq_max.
Machine : 8x-SKYLAKE-UMA
Benchmark : gitsource (time to run the git unit test suite)
Varying parameter : none
Unit : seconds (lower is better)
5.2.0 vanilla 5.2.0 intel_pstate/hwp 5.2.0 1C-turbo
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Amean 858.85 +- 1.16% ( ) 791.94 +- 0.21% ( 7.79%) 474.95 ( 44.70%)
5.2.0 3C-turbo 5.2.0 4C-turbo
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Amean 475.26 +- 0.20% ( 44.66%) 474.34 +- 0.13% ( 44.77%)
In this test, which is of interest as representing shell-intensive
(i.e. fork-intensive) serialized workloads, invariant schedutil outperforms
intel_pstate/powersave by a whopping 40% margin.
5.3.4 POWER CONSUMPTION, PERFORMANCE-PER-WATT
---------------------------------------------
The following table shows average power consumption in watt for each
benchmark. Data comes from turbostat (package average), which in turn is read
from the RAPL interface on CPUs. We know the patch affects CPU frequencies so
it's reasonable to ignore other power consumers (such as memory or I/O). Also,
we don't have a power meter available in the lab so RAPL is the best we have.
turbostat sampled average power every 10 seconds for the entire duration of
each benchmark. We took all those values and averaged them (i.e. with don't
have detail on a per-parameter granularity, only on whole benchmarks).
80x-BROADWELL-NUMA (power consumption, watts)
+--------+
BASELINE I_PSTATE 1C 3C | 4C | 8C
pgbench-ro 130.01 142.77 131.11 132.45 | 134.65 | 136.84
pgbench-rw 68.30 60.83 71.45 71.70 | 71.65 | 72.54
dbench4 90.25 59.06 101.43 99.89 | 101.10 | 102.94
netperf-udp 65.70 69.81 66.02 68.03 | 68.27 | 68.95
netperf-tcp 88.08 87.96 88.97 88.89 | 88.85 | 88.20
tbench4 142.32 176.73 153.02 163.91 | 165.58 | 176.07
kernbench 92.94 101.95 114.91 115.47 | 115.52 | 115.10
gitsource 40.92 41.87 75.14 75.20 | 75.40 | 75.70
+--------+
8x-SKYLAKE-UMA (power consumption, watts)
+--------+
BASELINE I_PSTATE/HWP 1C 3C | 4C |
pgbench-ro 46.49 46.68 46.56 46.59 | 46.52 |
pgbench-rw 29.34 31.38 30.98 31.00 | 31.00 |
dbench4 27.28 27.37 27.49 27.41 | 27.38 |
netperf-udp 22.33 22.41 22.36 22.35 | 22.36 |
netperf-tcp 27.29 27.29 27.30 27.31 | 27.33 |
tbench4 41.13 45.61 43.10 43.33 | 43.56 |
kernbench 42.56 42.63 43.01 43.01 | 43.01 |
gitsource 13.32 13.69 17.33 17.30 | 17.35 |
+--------+
48x-HASWELL-NUMA (power consumption, watts)
+--------+
BASELINE I_PSTATE 1C 3C | 4C | 12C
pgbench-ro 128.84 136.04 129.87 132.43 | 132.30 | 134.86
pgbench-rw 37.68 37.92 37.17 37.74 | 37.73 | 37.31
dbench4 28.56 28.73 28.60 28.73 | 28.70 | 28.79
netperf-udp 56.70 60.44 56.79 57.42 | 57.54 | 57.52
netperf-tcp 75.49 75.27 75.87 76.02 | 76.01 | 75.95
tbench4 115.44 139.51 119.53 123.07 | 123.97 | 130.22
kernbench 83.23 91.55 95.58 95.69 | 95.72 | 96.04
gitsource 36.79 36.99 39.99 40.34 | 40.35 | 40.23
+--------+
A lower power consumption isn't necessarily better, it depends on what is done
with that energy. Here are tables with the ratio of performance-per-watt on
each machine and benchmark. Higher is always better; a tilde (~) means a
neutral ratio (i.e. 1.00).
80x-BROADWELL-NUMA (performance-per-watt ratios; higher is better)
+------+
I_PSTATE 1C 3C | 4C | 8C
pgbench-ro 1.04 1.06 0.94 | 1.07 | 1.08
pgbench-rw 1.10 0.97 0.96 | 0.96 | 0.97
dbench4 1.24 0.94 0.95 | 0.94 | 0.92
netperf-udp ~ 1.02 1.02 | ~ | 1.02
netperf-tcp ~ 1.02 ~ | ~ | 1.02
tbench4 1.26 1.10 1.06 | 1.12 | 1.26
kernbench 0.98 0.97 0.97 | 0.97 | 0.98
gitsource ~ 1.11 1.11 | 1.11 | 1.13
+------+
8x-SKYLAKE-UMA (performance-per-watt ratios; higher is better)
+------+
I_PSTATE/HWP 1C 3C | 4C |
pgbench-ro ~ ~ ~ | ~ |
pgbench-rw 0.95 0.97 0.96 | 0.96 |
dbench4 ~ ~ ~ | ~ |
netperf-udp ~ ~ ~ | ~ |
netperf-tcp ~ ~ ~ | ~ |
tbench4 1.17 1.09 1.08 | 1.10 |
kernbench ~ ~ ~ | ~ |
gitsource 1.06 1.40 1.40 | 1.40 |
+------+
48x-HASWELL-NUMA (performance-per-watt ratios; higher is better)
+------+
I_PSTATE 1C 3C | 4C | 12C
pgbench-ro 1.09 ~ 1.09 | 1.03 | 1.11
pgbench-rw ~ 0.86 ~ | ~ | 0.86
dbench4 ~ 1.02 1.02 | 1.02 | ~
netperf-udp ~ 0.97 1.03 | 1.02 | ~
netperf-tcp 0.96 ~ ~ | ~ | ~
tbench4 1.24 ~ 1.06 | 1.05 | 1.11
kernbench 0.97 0.97 0.98 | 0.97 | 0.96
gitsource 1.03 1.33 1.32 | 1.32 | 1.33
+------+
These results are overall pleasing: in plenty of cases we observe
performance-per-watt improvements. The few regressions (read/write pgbench and
dbench on the Broadwell machine) are of small magnitude. kernbench loses a few
percentage points (it has a 10-15% performance improvement, but apparently the
increase in power consumption is larger than that). tbench4 and gitsource, which
benefit the most from the patch, keep a positive score in this table which is
a welcome surprise; that suggests that in those particular workloads the
non-invariant schedutil (and active intel_pstate, too) makes some rather
suboptimal frequency selections.
+-------------------------------------------------------------------------+
| 6. MICROARCH'ES ADDRESSED HERE
+-------------------------------------------------------------------------+
The patch addresses Xeon Core processors that use MSR_PLATFORM_INFO and
MSR_TURBO_RATIO_LIMIT to advertise their base frequency and turbo frequencies
respectively. This excludes the recent Xeon Scalable Performance processors
line (Xeon Gold, Platinum etc) whose MSRs have to be parsed differently.
Subsequent patches will address:
* Xeon Scalable Performance processors and Atom Goldmont/Goldmont Plus
* Xeon Phi (Knights Landing, Knights Mill)
* Atom Silvermont
+-------------------------------------------------------------------------+
| 7. REFERENCES
+-------------------------------------------------------------------------+
Tests have been run with the help of the MMTests performance testing
framework, see github.com/gormanm/mmtests. The configuration file names for
the benchmark used are:
db-pgbench-timed-ro-small-xfs
db-pgbench-timed-rw-small-xfs
io-dbench4-async-xfs
network-netperf-unbound
network-tbench
scheduler-unbound
workload-kerndevel-xfs
workload-shellscripts-xfs
hpc-nas-c-class-mpi-full-xfs
hpc-nas-c-class-omp-full
All those benchmarks are generally available on the web:
pgbench: https://www.postgresql.org/docs/10/pgbench.html
netperf: https://hewlettpackard.github.io/netperf/
dbench/tbench: https://dbench.samba.org/
gitsource: git unit test suite, github.com/git/git
NAS Parallel Benchmarks: https://www.nas.nasa.gov/publications/npb.html
hackbench: https://people.redhat.com/mingo/cfs-scheduler/tools/hackbench.c
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Doug Smythies <dsmythies@telus.net>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lkml.kernel.org/r/20200122151617.531-2-ggherdovich@suse.cz
|