From 69249c73d6dfcd41c93b913481e05b2ba01e54ad Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <email@example.com> Date: Tue, 28 Sep 2021 14:24:25 +0200 Subject: [PATCH 068/166] 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 <firstname.lastname@example.org> Signed-off-by: Sebastian Andrzej Siewior <email@example.com> Link: https://firstname.lastname@example.org --- kernel/sched/core.c | 4 ++++ 1 file changed, 4 insertions(+) Index: linux-5.15.32-rt39/kernel/sched/core.c =================================================================== @ linux-5.15.32-rt39/kernel/sched/core.c:78 @ __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.