[patch 2/5] sched: Disable TTWU_QUEUE on RT
From: Thomas Gleixner
Date: Tue Sep 28 2021 - 08:24:39 EST
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
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@xxxxxxxxxxxxx>
kernel/sched/features.h | 5 +++++
1 file changed, 5 insertions(+)
@@ -46,11 +46,16 @@ SCHED_FEAT(DOUBLE_TICK, false)
* Queue remote wakeups on the target CPU and process them
* using the scheduler IPI. Reduces rq->lock contention/bounces.
* When doing wakeups, attempt to limit superfluous scans of the LLC domain.