Subject: sched: Disable TTWU_QUEUE on RT From: Thomas Gleixner Date: Tue, 13 Sep 2011 16:42:35 +0200 Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.4/older/patches-5.4.3-rt1.tar.xz The queued remote wakeup mechanism can introduce rather large latencies if the number of migrated tasks is high. Disable it for RT. Signed-off-by: Thomas Gleixner --- kernel/sched/features.h | 5 +++++ 1 file changed, 5 insertions(+) --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -45,11 +45,16 @@ 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.