Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935630Ab3FTCVD (ORCPT ); Wed, 19 Jun 2013 22:21:03 -0400 Received: from mga03.intel.com ([143.182.124.21]:6154 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935556Ab3FTCVB (ORCPT ); Wed, 19 Jun 2013 22:21:01 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,901,1363158000"; d="scan'208";a="319759473" From: Alex Shi To: mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org, arjan@linux.intel.com, bp@alien8.de, pjt@google.com, namhyung@kernel.org, efault@gmx.de, morten.rasmussen@arm.com Cc: vincent.guittot@linaro.org, gregkh@linuxfoundation.org, preeti@linux.vnet.ibm.com, viresh.kumar@linaro.org, linux-kernel@vger.kernel.org, alex.shi@intel.com, len.brown@intel.com, rafael.j.wysocki@intel.com, jkosina@suse.cz, clark.williams@gmail.com, tony.luck@intel.com, keescook@chromium.org, mgorman@suse.de, riel@redhat.com Subject: [Resend patch v8 04/13] sched: fix slept time double counting in enqueue entity Date: Thu, 20 Jun 2013 10:18:48 +0800 Message-Id: <1371694737-29336-5-git-send-email-alex.shi@intel.com> X-Mailer: git-send-email 1.7.12 In-Reply-To: <1371694737-29336-1-git-send-email-alex.shi@intel.com> References: <1371694737-29336-1-git-send-email-alex.shi@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1698 Lines: 47 The wakeuped migrated task will __synchronize_entity_decay(se); in migrate_task_rq_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. Paul also contribute some code comments in this commit. Signed-off-by: Alex Shi Reviewed-by: Paul Turner --- kernel/sched/fair.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) 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 */ -- 1.7.12 -- 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/