The following commit has been merged into the sched/urgent branch of tip: Commit-ID: 68f7b5cc835de7d5b6c7696533c126018171e793 Gitweb: https://git.kernel.org/tip/68f7b5cc835de7d5b6c7696533c126018171e793 Author: Vincent Guittot <vincent.guittot@xxxxxxxxxx> AuthorDate: Wed, 24 Jun 2020 17:44:22 +02:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Thu, 25 Jun 2020 13:45:38 +02:00 sched/cfs: change initial value of runnable_avg Some performance regression on reaim benchmark have been raised with commit 070f5e860ee2 ("sched/fair: Take into account runnable_avg to classify group") The problem comes from the init value of runnable_avg which is initialized with max value. This can be a problem if the newly forked task is finally a short task because the group of CPUs is wrongly set to overloaded and tasks are pulled less agressively. Set initial value of runnable_avg equals to util_avg to reflect that there is no waiting time so far. Fixes: 070f5e860ee2 ("sched/fair: Take into account runnable_avg to classify group") Reported-by: kernel test robot <rong.a.chen@xxxxxxxxx> Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20200624154422.29166-1-vincent.guittot@xxxxxxxxxx --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index cbcb2f7..658aa7a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -806,7 +806,7 @@ void post_init_entity_util_avg(struct task_struct *p) } } - sa->runnable_avg = cpu_scale; + sa->runnable_avg = sa->util_avg; if (p->sched_class != &fair_sched_class) { /*
![]() |