Messages in this thread | | | Date | Fri, 11 May 2018 11:14:39 +0530 | From | Viresh Kumar <> | Subject | Re: [PATCH 2/3] sched/fair: util_est: update before schedutil |
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On 10-05-18, 16:05, Patrick Bellasi wrote: > When a task is enqueue the estimated utilization of a CPU is updated > to better support the selection of the required frequency. > However, schedutil is (implicitly) updated by update_load_avg() which > always happens before util_est_{en,de}queue(), thus potentially > introducing a latency between estimated utilization updates and > frequency selections. > > Let's update util_est at the beginning of enqueue_task_fair(), > which will ensure that all schedutil updates will see the most > updated estimated utilization value for a CPU. > > Reported-by: Vincent Guittot <vincent.guittot@linaro.org> > Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Vincent Guittot <vincent.guittot@linaro.org> > Cc: linux-kernel@vger.kernel.org > Cc: linux-pm@vger.kernel.org > --- > kernel/sched/fair.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-)
Fixes and Stable ?
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 1f6a23a5b451..01dfc47541e6 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -5356,6 +5356,9 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) > struct cfs_rq *cfs_rq; > struct sched_entity *se = &p->se; > > + /* Estimated utilization must be updated before schedutil */ > + util_est_enqueue(&rq->cfs, p); > + > /* > * If in_iowait is set, the code below may not trigger any cpufreq > * utilization updates, so do it here explicitly with the IOWAIT flag > @@ -5397,7 +5400,6 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) > if (!se) > add_nr_running(rq, 1); > > - util_est_enqueue(&rq->cfs, p); > hrtick_update(rq); > }
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
-- viresh
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