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| author |   Thomas Gleixner <tglx@linutronix.de> | 2021-09-28 14:24:27 +0200 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2021-10-05 15:52:12 +0200 |
| commit | 539fbb5be0da56ffa1434b4f56521a0522bd1d61 (patch) | |
| tree | 7721f47f5779786d4543a9419dcaf3bb110be274 /kernel/sched/features.h | |
| parent | sched: Limit the number of task migrations per batch on RT (diff) | |
| download | linux-dev-539fbb5be0da56ffa1434b4f56521a0522bd1d61.tar.xz linux-dev-539fbb5be0da56ffa1434b4f56521a0522bd1d61.zip | |
sched: Disable TTWU_QUEUE on RT
The queued remote wakeup mechanism has turned out to be suboptimal for RT
enabled kernels. The maximum latencies go up by a factor of > 5x in certain
scenarious.
This is caused by either long wake lists or by a large number of TTWU IPIs
which are processed back to back.
Disable it for RT.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210928122411.482262764@linutronix.de
Diffstat (limited to 'kernel/sched/features.h')
| -rw-r--r-- | kernel/sched/features.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/sched/features.h b/kernel/sched/features.h index 7f8dace0964c..1cf435bbcd9c 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -46,11 +46,16 @@ SCHED_FEAT(DOUBLE_TICK, false) */ SCHED_FEAT(NONTASK_CAPACITY, true) +#ifdef CONFIG_PREEMPT_RT +SCHED_FEAT(TTWU_QUEUE, false) +#else + /* * Queue remote wakeups on the target CPU and process them * using the scheduler IPI. Reduces rq->lock contention/bounces. */ SCHED_FEAT(TTWU_QUEUE, true) +#endif /* * When doing wakeups, attempt to limit superfluous scans of the LLC domain. |