Commit 691925f3 authored Sep 28, 2021 by Thomas Gleixner Committed by Peter Zijlstra Oct 05, 2021

sched: Limit the number of task migrations per batch on RT



Batched task migrations are a source for large latencies as they keep the
scheduler from running while processing the migrations.

Limit the batch size to 8 instead of 32 when running on a RT enabled
kernel.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210928122411.425097596@linutronix.de

parent 8d491de6

kernel/sched/core.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -74,7 +74,11 @@ __read_mostly int sysctl_resched_latency_warn_once = 1;
		* Number of tasks to iterate in a single balance run.
		* Limited because this is done with IRQs disabled.
		*/
		#ifdef CONFIG_PREEMPT_RT
		const_debug unsigned int sysctl_sched_nr_migrate = 8;
		#else
		const_debug unsigned int sysctl_sched_nr_migrate = 32;
		#endif

		/*
		* period over which we measure -rt task CPU usage in us.