Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932828Ab3DDCEt (ORCPT ); Wed, 3 Apr 2013 22:04:49 -0400 Received: from mga03.intel.com ([143.182.124.21]:29711 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932802Ab3DDCCd (ORCPT ); Wed, 3 Apr 2013 22:02:33 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,404,1363158000"; d="scan'208";a="280534450" 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: [patch v7 12/21] sched: using avg_idle to detect bursty wakeup Date: Thu, 4 Apr 2013 10:00:53 +0800 Message-Id: <1365040862-8390-13-git-send-email-alex.shi@intel.com> X-Mailer: git-send-email 1.7.12 In-Reply-To: <1365040862-8390-1-git-send-email-alex.shi@intel.com> References: <1365040862-8390-1-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: 1531 Lines: 44 Sleeping task has no utiliation, when they were bursty waked up, the zero utilization make scheduler out of balance, like aim7 benchmark. rq->avg_idle is 'to used to accommodate bursty loads in a dirt simple dirt cheap manner' -- Mike Galbraith. With this cheap and smart bursty indicator, we can find the wake up burst, and use nr_running as instant utilization in this scenario. For other scenarios, we still use the precise CPU utilization to judage if a domain is eligible for power scheduling. Thanks for Mike Galbraith's idea! Thanks for Namhyung's suggestion to compact the burst into max_rq_util()! Signed-off-by: Alex Shi --- kernel/sched/fair.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index f610313..a729939 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3363,6 +3363,10 @@ static unsigned int max_rq_util(int cpu) unsigned int cfs_util; unsigned int nr_running; + /* use nr_running as instant utilization for burst cpu */ + if (cpu_rq(cpu)->avg_idle < sysctl_sched_burst_threshold) + return rq->nr_running * FULL_UTIL; + /* yield cfs utilization to rt's, if total utilization > 100% */ cfs_util = min(rq->util, (unsigned int)(FULL_UTIL - rt_util)); -- 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/