From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933466Ab3CUJ1T (ORCPT ); Thu, 21 Mar 2013 05:27:19 -0400 Received: from mga14.intel.com ([143.182.124.37]:26285 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932084Ab3CUJ1S (ORCPT ); Thu, 21 Mar 2013 05:27:18 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,884,1355126400"; d="scan'208";a="274002934" Message-ID: <514AD26F.9010905@intel.com> Date: Thu, 21 Mar 2013 17:27:11 +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: Preeti U Murthy CC: mingo@redhat.com, peterz@infradead.org, efault@gmx.de, torvalds@linux-foundation.org, tglx@linutronix.de, akpm@linux-foundation.org, arjan@linux.intel.com, bp@alien8.de, pjt@google.com, namhyung@kernel.org, vincent.guittot@linaro.org, gregkh@linuxfoundation.org, viresh.kumar@linaro.org, linux-kernel@vger.kernel.org, morten.rasmussen@arm.com Subject: Re: [patch v5 14/15] sched: power aware load balance References: <1361164062-20111-1-git-send-email-alex.shi@intel.com> <1361164062-20111-15-git-send-email-alex.shi@intel.com> <514941C5.6080007@linux.vnet.ibm.com> <514ABA19.1080807@intel.com> <514AC7B2.7030400@linux.vnet.ibm.com> In-Reply-To: <514AC7B2.7030400@linux.vnet.ibm.com> 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 03/21/2013 04:41 PM, Preeti U Murthy wrote: >> > > Yes, I did find this behaviour on a 2 socket, 8 core machine very > consistently. > > rq->util cannot go to 0, after it has begun accumulating load right? > > Say a load was running on a runqueue which had its rq->util to be at > 100%. After the load finishes, the runqueue goes idle. For every > scheduler tick, its utilisation decays. But can never become 0. > > rq->util = rq->avg.runnable_avg_sum/rq->avg.runnable_avg_period did you close all of background system services? In theory the rq->avg.runnable_avg_sum should be zero if there is no task a bit long, otherwise there are some bugs in kernel. Could you check the value under /proc/sched_debug? -- Thanks Alex