From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752768Ab3FQPmE (ORCPT ); Mon, 17 Jun 2013 11:42:04 -0400 Received: from mga02.intel.com ([134.134.136.20]:1708 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750903Ab3FQPmC (ORCPT ); Mon, 17 Jun 2013 11:42:02 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,881,1363158000"; d="scan'208";a="351127240" Message-ID: <51BF2E37.5040400@intel.com> Date: Mon, 17 Jun 2013 23:41:43 +0800 From: Alex Shi User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120912 Thunderbird/15.0.1 MIME-Version: 1.0 To: Paul Turner CC: Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Andrew Morton , Borislav Petkov , Namhyung Kim , Mike Galbraith , Morten Rasmussen , Vincent Guittot , Preeti U Murthy , Viresh Kumar , LKML , Mel Gorman , Rik van Riel , Michael Wang , Jason Low , Changlong Xie , sgruszka@redhat.com, =?ISO-8859-1?Q?Fr=E9d=E9ric_Weisbecker?= Subject: Re: [patch v8 4/9] sched: fix slept time double counting in enqueue entity References: <1370589652-24549-1-git-send-email-alex.shi@intel.com> <1370589652-24549-5-git-send-email-alex.shi@intel.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/17/2013 07:51 PM, Paul Turner wrote: > Can you add something like: > > + /* > + * Task re-woke on same cpu (or else > migrate_task_rq_fair() > + * would have made count negative); we must be careful > to avoid > + * double-accounting blocked time after synchronizing > decays. > + */ > > > Reviewed-by: Paul Turner thanks for review! --- >>From 24d9b43e7a269e6ffee5b874d39812b83812a809 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Thu, 9 May 2013 10:54:13 +0800 Subject: [PATCH] sched: fix slept time double counting in enqueue entity The wakeuped migrated task will __synchronize_entity_decay(se); in migrate_task_fair, then it needs to set `se->avg.last_runnable_update -= (-se->avg.decay_count) << 20' before update_entity_load_avg, in order to avoid slept time is updated twice for se.avg.load_avg_contrib in both __syncchronize and update_entity_load_avg. but if the slept task is waked up from self cpu, it miss the last_runnable_update before update_entity_load_avg(se, 0, 1), then the slept time was used twice in both functions. So we need to remove the double slept time counting. Signed-off-by: Alex Shi Reviewed-by: Paul Turner --- kernel/sched/fair.c | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index df5b8a9..1e5a5e6 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1571,7 +1571,13 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, } wakeup = 0; } else { - __synchronize_entity_decay(se); + /* + * Task re-woke on same cpu (or else migrate_task_rq_fair() + * would have made count negative); we must be careful to avoid + * double-accounting blocked time after synchronizing decays. + */ + se->avg.last_runnable_update += __synchronize_entity_decay(se) + << 20; } /* migrated tasks did not contribute to our blocked load */ -- 1.7.5.4