From d944dd60ea381b06696f77f6900bfad524f0c5b8 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 13 Sep 2011 16:42:35 +0200 Subject: [PATCH 112/325] sched: Disable TTWU_QUEUE on RT Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.115-rt48.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(+) diff --git a/kernel/sched/features.h b/kernel/sched/features.h index 85ae8488039c..68de18405857 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -46,11 +46,16 @@ SCHED_FEAT(LB_BIAS, true) */ SCHED_FEAT(NONTASK_CAPACITY, true) +#ifdef CONFIG_PREEMPT_RT_FULL +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. -- 2.25.1