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[209.132.180.67]) by mx.google.com with ESMTP id k43si4305412edb.150.2019.10.31.08.50.03; Thu, 31 Oct 2019 08:50:27 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=dh4TGDJt; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728458AbfJaPsu (ORCPT + 99 others); Thu, 31 Oct 2019 11:48:50 -0400 Received: from mail-lj1-f194.google.com ([209.85.208.194]:39740 "EHLO mail-lj1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726664AbfJaPsu (ORCPT ); Thu, 31 Oct 2019 11:48:50 -0400 Received: by mail-lj1-f194.google.com with SMTP id y3so7167694ljj.6 for ; Thu, 31 Oct 2019 08:48:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=260kgN6VgY6Es3AEFNd7jvs6pF/ZLC/U45J3qC3o/uw=; b=dh4TGDJtErpngjh3cftUdxn1H6gwpzif+48xDGcGO4LGaRGJoBtzVgEcC3ZzOSoMyj wIr5lM3nHRu7jgj0Rs1AXUp0t/k1QyqRfNdj58AMOdb99NjWhInTJjqFyucZedX82W5X L9nJBqgwgnKbOtcZpIw56vM+UUn4IFHVOf5KBlNRwVu1yxiG4yS7CjaKQOXkHK7P+B2U gOOIl6j5sCAquS/lgAbmeMVIFdxUJ4sngLAhLfTIVmmVHYSIXHZeO2riREnuMRq0rqnS ZkKYsCDhCfUiNWCtmhjmleoZG7d0OhRLKz80orPetY+RBKT80asOHnzT3TRJ7f6HjLi4 7VQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=260kgN6VgY6Es3AEFNd7jvs6pF/ZLC/U45J3qC3o/uw=; b=jjBUCF3/WZZTvavwvoLZjxRb74O2mBh89qTbIeMtx2u8X5A2h1P5r26jbZOdvcENne k2vDzZNTTBLLKrgC+YHhiAVytRQsi7TenKiuzIkI5nz1YitvWXPIle0PJsNnVy3Sn7P2 DRFXueR052p2aUYVn8m/ZmmsfmvM4c6lewwPLfc/iu08T+VpgIm6eAkYztatBqZf8YYf pjaFnOtnwTJ/TvxDcJvZ6fBsbrwjuBw8X2Tm0v47efOukTNs1HzZv5LffPLdfbmkhtDy q2+TGW8DyWXipdldQTc+XAWcFQWmG1DhyJx6rRYp0cZc0YTslzs3F0TfvZaO03Iubm2h 2j8Q== X-Gm-Message-State: APjAAAUTTWcKHs+pVNSTWgoUKC1i2Rpv0gIQHG8KC/uIpeuhblotEsKE IXpV187x9q9unAELq5UOu5Xh8y95Fx70n41ADm6E1w== X-Received: by 2002:a2e:a16d:: with SMTP id u13mr4890381ljl.214.1572536926284; Thu, 31 Oct 2019 08:48:46 -0700 (PDT) MIME-Version: 1.0 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> In-Reply-To: From: Vincent Guittot Date: Thu, 31 Oct 2019 16:48:34 +0100 Message-ID: Subject: Re: [Patch v4 4/6] sched/fair: update cpu_capcity to reflect thermal pressure To: Dietmar Eggemann Cc: Qais Yousef , Peter Zijlstra , Thara Gopinath , Ingo Molnar , Ionela Voinescu , Zhang Rui , Eduardo Valentin , Quentin Perret , linux-kernel , Amit Kachhap , Javi Merino , Daniel Lezcano Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 31 Oct 2019 at 16:38, Dietmar Eggemann wrote: > > On 31.10.19 11:53, 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? > > > > If I managed to get it right somehow. It'd be nice if we can do inverse > > conversion on delta_capacity so that avg_thermal.{load_avg, util_avg} meaning > > is consistent across the board. But I don't feel strongly about it if this gets > > documented properly. > > So why can't we use rq->avg_thermal.util_avg here? Since capacity is > closer to util than to load? > > Is it because you want to use the influence of ___update_load_sum(..., > unsigned long load eq. per-cpu delta_capacity in your signal? > > Why not call it this way then? util_avg tracks a binary state with 2 fixed weights: running(1024) vs not running (0) In the case of thermal pressure, we want to track how much pressure is put on the CPU: capping to half the max frequency is not the same as capping only 10% load_avg is not boolean but you set the weight you want to apply and this weight reflects the amount of pressure. > > diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c > index 38210691c615..d3035457483f 100644 > --- a/kernel/sched/pelt.c > +++ b/kernel/sched/pelt.c > @@ -357,9 +357,9 @@ int update_thermal_load_avg(u64 now, struct rq *rq, > u64 capacity) > { > if (___update_load_sum(now, &rq->avg_thermal, > capacity, > - capacity, > - capacity)) { > - ___update_load_avg(&rq->avg_thermal, 1, 1); > + 0, > + 0)) { > + ___update_load_avg(&rq->avg_thermal, 1, 0); > return 1; > }