From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752642AbeEKIlY (ORCPT ); Fri, 11 May 2018 04:41:24 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:38038 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752165AbeEKIlW (ORCPT ); Fri, 11 May 2018 04:41:22 -0400 Date: Fri, 11 May 2018 09:41:17 +0100 From: Patrick Bellasi To: Viresh Kumar Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Ingo Molnar , Peter Zijlstra , "Rafael J . Wysocki" , Vincent Guittot , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Joel Fernandes , Steve Muckle Subject: Re: [PATCH 2/3] sched/fair: util_est: update before schedutil Message-ID: <20180511084117.GC30654@e110439-lin> References: <20180510150553.28122-1-patrick.bellasi@arm.com> <20180510150553.28122-3-patrick.bellasi@arm.com> <20180511054439.slrpscgm6ivho5qy@vireshk-i7> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180511054439.slrpscgm6ivho5qy@vireshk-i7> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11-May 11:14, Viresh Kumar wrote: > 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 > > Signed-off-by: Patrick Bellasi > > Cc: Ingo Molnar > > Cc: Peter Zijlstra > > Cc: Vincent Guittot > > 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 ? Good idea, will add them. > > 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 -- #include Patrick Bellasi