Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755681AbbGVNmc (ORCPT ); Wed, 22 Jul 2015 09:42:32 -0400 Received: from foss.arm.com ([217.140.101.70]:35991 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752203AbbGVNma (ORCPT ); Wed, 22 Jul 2015 09:42:30 -0400 Date: Wed, 22 Jul 2015 14:45:23 +0100 From: Morten Rasmussen To: Leo Yan Cc: peterz@infradead.org, mingo@redhat.com, vincent.guittot@linaro.org, daniel.lezcano@linaro.org, Dietmar Eggemann , yuyang.du@intel.com, mturquette@baylibre.com, rjw@rjwysocki.net, Juri Lelli , sgurrappadi@nvidia.com, pang.xunlei@zte.com.cn, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [RFCv5 PATCH 11/46] sched: Remove blocked load and utilization contributions of dying tasks Message-ID: <20150722134523.GB21785@e105550-lin.cambridge.arm.com> References: <1436293469-25707-1-git-send-email-morten.rasmussen@arm.com> <1436293469-25707-12-git-send-email-morten.rasmussen@arm.com> <20150722065101.GA719@leoy-linaro> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150722065101.GA719@leoy-linaro> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1958 Lines: 48 On Wed, Jul 22, 2015 at 02:51:01PM +0800, Leo Yan wrote: > On Tue, Jul 07, 2015 at 07:23:54PM +0100, Morten Rasmussen wrote: > > Tasks being dequeued for the last time (state == TASK_DEAD) are dequeued > > with the DEQUEUE_SLEEP flag which causes their load and utilization > > contributions to be added to the runqueue blocked load and utilization. > > Hence they will contain load or utilization that is gone away. The issue > > only exists for the root cfs_rq as cgroup_exit() doesn't set > > DEQUEUE_SLEEP for task group exits. > > > > If runnable+blocked load is to be used as a better estimate for cpu > > load the dead task contributions need to be removed to prevent > > load_balance() (idle_balance() in particular) from over-estimating the > > cpu load. > > > > cc: Ingo Molnar > > cc: Peter Zijlstra > > > > Signed-off-by: Morten Rasmussen > > --- > > kernel/sched/fair.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 775b0c7..fa12ce5 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -3217,6 +3217,8 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) > > * Update run-time statistics of the 'current'. > > */ > > update_curr(cfs_rq); > > + if (entity_is_task(se) && task_of(se)->state == TASK_DEAD) > > + flags &= !DEQUEUE_SLEEP; > > So flags will be set to zero? Could be replaced by "flags &= ~DEQUEUE_SLEEP"? Not could, should :) I meant to clear the flag, but used the wrong operator. We only have DEQUEUE_SLEEP and 0 at the moment so it doesn't matter, but it might later. Thanks, Morten -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/