Messages in this thread Patch in this message | | | Date | Mon, 10 Sep 2018 03:15:27 -0700 | From | tip-bot for Valentin Schneider <> | Subject | [tip:sched/core] sched/fair: Kick nohz balance if rq->misfit_task_load |
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Commit-ID: 5fbdfae5221a5208ed8e7653fc1c4b31de420f74 Gitweb: https://git.kernel.org/tip/5fbdfae5221a5208ed8e7653fc1c4b31de420f74 Author: Valentin Schneider <valentin.schneider@arm.com> AuthorDate: Wed, 4 Jul 2018 11:17:43 +0100 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Mon, 10 Sep 2018 11:05:51 +0200
sched/fair: Kick nohz balance if rq->misfit_task_load
There already are a few conditions in nohz_kick_needed() to ensure a nohz kick is triggered, but they are not enough for some misfit task scenarios. Excluding asym packing, those are:
- rq->nr_running >=2: Not relevant here because we are running a misfit task, it needs to be migrated regardless and potentially through active balance.
- sds->nr_busy_cpus > 1: If there is only the misfit task being run on a group of low capacity CPUs, this will be evaluated to False.
- rq->cfs.h_nr_running >=1 && check_cpu_capacity(): Not relevant here, misfit task needs to be migrated regardless of rt/IRQ pressure
As such, this commit adds an rq->misfit_task_load condition to trigger a nohz kick.
The idea to kick a nohz balance for misfit tasks originally came from Leo Yan <leo.yan@linaro.org>, and a similar patch was submitted for the Android Common Kernel - see:
https://lists.linaro.org/pipermail/eas-dev/2016-September/000551.html
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-6-git-send-email-morten.rasmussen@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> --- 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 24fe39e57bc3..e08287d3806f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9135,7 +9135,7 @@ static void nohz_balancer_kick(struct rq *rq) if (time_before(now, nohz.next_balance)) goto out; - if (rq->nr_running >= 2) { + if (rq->nr_running >= 2 || rq->misfit_task_load) { flags = NOHZ_KICK_MASK; goto out; }
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