From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753742Ab3BUNdQ (ORCPT ); Thu, 21 Feb 2013 08:33:16 -0500 Received: from merlin.infradead.org ([205.233.59.134]:38869 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752704Ab3BUNdO (ORCPT ); Thu, 21 Feb 2013 08:33:14 -0500 Message-ID: <1361453587.26780.18.camel@laptop> Subject: Re: [patch v5 09/15] sched: add power aware scheduling in fork/exec/wake From: Peter Zijlstra To: Alex Shi Cc: torvalds@linux-foundation.org, mingo@redhat.com, tglx@linutronix.de, akpm@linux-foundation.org, arjan@linux.intel.com, bp@alien8.de, pjt@google.com, namhyung@kernel.org, efault@gmx.de, vincent.guittot@linaro.org, gregkh@linuxfoundation.org, preeti@linux.vnet.ibm.com, viresh.kumar@linaro.org, linux-kernel@vger.kernel.org, morten.rasmussen@arm.com Date: Thu, 21 Feb 2013 14:33:07 +0100 In-Reply-To: <5124DC76.2010801@intel.com> References: <1361164062-20111-1-git-send-email-alex.shi@intel.com> <1361164062-20111-10-git-send-email-alex.shi@intel.com> <1361353360.10155.9.camel@laptop> <5124BCEB.8030606@intel.com> <1361367371.10155.32.camel@laptop> <5124DC76.2010801@intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.2-0ubuntu0.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2013-02-20 at 22:23 +0800, Alex Shi wrote: > > But but but,... nr_running is completely unrelated to utilization. > > > > Actually, I also hesitated on the name, how about using nr_running to > replace group_util directly? The name is a secondary issue, first you need to explain why you think nr_running is a useful metric at all. You can have a high nr_running and a low utilization (a burst of wakeups, each waking a process that'll instantly go to sleep again), or low nr_running and high utilization (a single process cpu bound process). There is absolutely no relation between utilization and nr_running, building something on that assumption is just wrong and broken.