From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934057AbbELTpQ (ORCPT ); Tue, 12 May 2015 15:45:16 -0400 Received: from foss.arm.com ([217.140.101.70]:33830 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933808AbbELTiP (ORCPT ); Tue, 12 May 2015 15:38:15 -0400 From: Morten Rasmussen To: peterz@infradead.org, mingo@redhat.com Cc: vincent.guittot@linaro.org, Dietmar Eggemann , yuyang.du@intel.com, preeti@linux.vnet.ibm.com, mturquette@linaro.org, rjw@rjwysocki.net, Juri Lelli , sgurrappadi@nvidia.com, pang.xunlei@zte.com.cn, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, morten.rasmussen@arm.com Subject: [RFCv4 PATCH 11/34] sched: Remove blocked load and utilization contributions of dying tasks Date: Tue, 12 May 2015 20:38:46 +0100 Message-Id: <1431459549-18343-12-git-send-email-morten.rasmussen@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1431459549-18343-1-git-send-email-morten.rasmussen@arm.com> References: <1431459549-18343-1-git-send-email-morten.rasmussen@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Task 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 e40cd88..d045404 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3202,6 +3202,8 @@ 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; dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP); update_stats_dequeue(cfs_rq, se); -- 1.9.1