From e0da3b8be9bc430e4e9aaf363de830a6378fef88 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 28 Sep 2021 14:24:25 +0200 Subject: [PATCH 068/158] 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 Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20210928122411.425097596@linutronix.de --- kernel/sched/core.c | 4 ++++ 1 file changed, 4 insertions(+) Index: linux-5.15.19-rt29/kernel/sched/core.c =================================================================== --- linux-5.15.19-rt29.orig/kernel/sched/core.c +++ linux-5.15.19-rt29/kernel/sched/core.c @@ -74,7 +74,11 @@ __read_mostly int sysctl_resched_latency * 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.