Messages in this thread Patch in this message | | | From | Morten Rasmussen <> | Subject | [PATCHv4 05/12] sched/fair: Kick nohz balance if rq->misfit_task_load | Date | Wed, 4 Jul 2018 11:17:43 +0100 |
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From: Valentin Schneider <valentin.schneider@arm.com>
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 [1].
[1]: https://lists.linaro.org/pipermail/eas-dev/2016-September/000551.html
cc: Ingo Molnar <mingo@redhat.com> cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> --- 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 6e885d92fad2..acec93e1dc51 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9505,7 +9505,7 @@ 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; } -- 2.7.4
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