Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758202AbaGOJUq (ORCPT ); Tue, 15 Jul 2014 05:20:46 -0400 Received: from mail-oa0-f50.google.com ([209.85.219.50]:54441 "EHLO mail-oa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757894AbaGOJUm (ORCPT ); Tue, 15 Jul 2014 05:20:42 -0400 MIME-Version: 1.0 In-Reply-To: <20140711201238.GY20603@laptop.programming.kicks-ass.net> References: <1404144343-18720-1-git-send-email-vincent.guittot@linaro.org> <1404144343-18720-10-git-send-email-vincent.guittot@linaro.org> <20140710131646.GB3935@laptop> <20140711151304.GD3935@laptop> <20140711201238.GY20603@laptop.programming.kicks-ass.net> From: Vincent Guittot Date: Tue, 15 Jul 2014 11:20:21 +0200 Message-ID: Subject: Re: [PATCH v3 09/12] Revert "sched: Put rq's sched_avg under CONFIG_FAIR_GROUP_SCHED" To: Peter Zijlstra Cc: Ingo Molnar , linux-kernel , Russell King - ARM Linux , LAK , Preeti U Murthy , Morten Rasmussen , Mike Galbraith , Nicolas Pitre , "linaro-kernel@lists.linaro.org" , Daniel Lezcano , Dietmar Eggemann Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11 July 2014 22:12, Peter Zijlstra wrote: > On Fri, Jul 11, 2014 at 07:39:29PM +0200, Vincent Guittot wrote: >> In my mind, arch_scale_cpu_freq was intend to scale the capacity of >> the CPU according to the current dvfs operating point. >> As it's no more use anywhere now that we have arch_scale_cpu, we could >> probably remove it .. and see when it will become used. > > I probably should have written comments when I wrote that code, but it > was meant to be used only where, as described above, we limit things. > Ondemand and such, which will temporarily decrease freq, will ramp it up > again at demand, and therefore lowering the capacity will skew things. > > You'll put less load on because its run slower, and then you'll run it > slower because there's less load on -> cyclic FAIL. > >> > In that same discussion ISTR a suggestion about adding avg_running time, >> > as opposed to the current avg_runnable. The sum of avg_running should be >> > much more accurate, and still react correctly to migrations. >> >> I haven't look in details but I agree that avg_running would be much >> more accurate than avg_runnable and should probably fit the >> requirement. Does it means that we could re-add the avg_running (or >> something similar) that has disappeared during the review of load avg >> tracking patchset ? > > Sure, I think we killed it there because there wasn't an actual use for > it and I'm always in favour of stripping everything to their bare bones, > esp big and complex things. > > And then later, add things back once we have need for it. Ok, i'm going to look how to add it back taking nto account current Yuyang's rework of load_avg > -- > 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/ -- 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/