From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3CD74CA9ECB for ; Thu, 31 Oct 2019 16:57:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1AFD02087F for ; Thu, 31 Oct 2019 16:57:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728764AbfJaQ5B (ORCPT ); Thu, 31 Oct 2019 12:57:01 -0400 Received: from foss.arm.com ([217.140.110.172]:52308 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728685AbfJaQ5B (ORCPT ); Thu, 31 Oct 2019 12:57:01 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D6F3A1FB; Thu, 31 Oct 2019 09:57:00 -0700 (PDT) Received: from e107158-lin.cambridge.arm.com (unknown [10.1.195.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4D0743F6C4; Thu, 31 Oct 2019 09:56:59 -0700 (PDT) Date: Thu, 31 Oct 2019 16:56:57 +0000 From: Qais Yousef To: Thara Gopinath Cc: Peter Zijlstra , mingo@redhat.com, ionela.voinescu@arm.com, vincent.guittot@linaro.org, rui.zhang@intel.com, edubezval@gmail.com, qperret@google.com, linux-kernel@vger.kernel.org, amit.kachhap@gmail.com, javi.merino@kernel.org, daniel.lezcano@linaro.org Subject: Re: [Patch v4 4/6] sched/fair: update cpu_capcity to reflect thermal pressure Message-ID: <20191031165656.oad63hug4t7nlopl@e107158-lin.cambridge.arm.com> References: <1571776465-29763-1-git-send-email-thara.gopinath@linaro.org> <1571776465-29763-5-git-send-email-thara.gopinath@linaro.org> <20191023122252.dz7obopab6iizy4s@e107158-lin.cambridge.arm.com> <20191028153010.GE4097@hirez.programming.kicks-ass.net> <20191031105342.b3sl5xhysldfla3g@e107158-lin.cambridge.arm.com> <5DBB05BC.40502@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <5DBB05BC.40502@linaro.org> User-Agent: NeoMutt/20171215 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/31/19 12:03, Thara Gopinath wrote: > On 10/31/2019 06:53 AM, Qais Yousef wrote: > > On 10/28/19 16:30, Peter Zijlstra wrote: > >> On Wed, Oct 23, 2019 at 01:28:40PM +0100, Qais Yousef wrote: > >>> On 10/22/19 16:34, Thara Gopinath wrote: > >>>> cpu_capacity relflects the maximum available capacity of a cpu. Thermal > >>>> pressure on a cpu means this maximum available capacity is reduced. This > >>>> patch reduces the average thermal pressure for a cpu from its maximum > >>>> available capacity so that cpu_capacity reflects the actual > >>>> available capacity. > >>>> > >>>> Signed-off-by: Thara Gopinath > >>>> --- > >>>> kernel/sched/fair.c | 1 + > >>>> 1 file changed, 1 insertion(+) > >>>> > >>>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > >>>> index 4f9c2cb..be3e802 100644 > >>>> --- a/kernel/sched/fair.c > >>>> +++ b/kernel/sched/fair.c > >>>> @@ -7727,6 +7727,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, int cpu) > >>>> > >>>> used = READ_ONCE(rq->avg_rt.util_avg); > >>>> used += READ_ONCE(rq->avg_dl.util_avg); > >>>> + used += READ_ONCE(rq->avg_thermal.load_avg); > >>> > >>> Maybe a naive question - but can we add util_avg with load_avg without > >>> a conversion? I thought the 2 signals have different properties. > >> > >> Changelog of patch #1 explains, it's in that dense blob of text. > >> > >> But yes, you're quite right that that wants a comment here. > > > > Thanks for the pointer! A comment would be nice indeed. > > > > To make sure I got this correctly - it's because avg_thermal.load_avg > > represents delta_capacity which is already a 'converted' form of load. So this > > makes avg_thermal.load_avg a util_avg really. Correct? > Hello Quais, > > Sorry for not replying to your earlier email. Thanks for the review. > So if you look at the code, util_sum in calculated as a binary signal > converted into capacity. Check out the the below snippet from accumulate_sum > > if (load) > sa->load_sum += load * contrib; > if (runnable) > sa->runnable_load_sum += runnable * contrib; > if (running) > sa->util_sum += contrib << SCHED_CAPACITY_SHIFT; > > So the actual delta for the thermal pressure will never be considered > if util_avg is used. > > I will update this patch with relevant comment. Okay thanks for the explanation. -- Qais Yousef