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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 2DF62C43441 for ; Thu, 22 Nov 2018 13:56:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E8F5C20684 for ; Thu, 22 Nov 2018 13:56:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="j+3wDzzi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E8F5C20684 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391566AbeKWAft (ORCPT ); Thu, 22 Nov 2018 19:35:49 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:51378 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730633AbeKWAft (ORCPT ); Thu, 22 Nov 2018 19:35:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=5a2LqsCdGJOKGLI+ozOYHganhhU+CTNqkX5uajpFs5k=; b=j+3wDzziYk+cYHgmzLluq8/PT MPW40qEgdclgD2a+sr6CVSHSYkOgd5Atj0jBj8sC2bTbWXaPxt+xhsSenH96tPX5GQ5IifvGaLe/C 4oHDgljPtwYntx0dJmM1Q4GIXGvKKkkHaQkJQm+ZYlutSlffPErCVhFqRSC/TABUUsQi5QVUSKkb+ Dk01TIPyLoB2JTDixsfRImXdE2EjKao6yvjUJjQcyRVJeDLxDuYXOKhgdvkCdRTKK7dA9EbTkRKSF X4UCzEW0+M3ozZggDGpvFGEP8i+hAzmJdpw5q1i3QJP+OxaKHem4RRS1vVmv95ro9gVRgnbn2fQ5O 6nzrld2GQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gPpSo-0005ax-DR; Thu, 22 Nov 2018 13:56:14 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id A262D2029FD58; Thu, 22 Nov 2018 14:56:06 +0100 (CET) Date: Thu, 22 Nov 2018 14:56:06 +0100 From: Peter Zijlstra To: Quentin Perret Cc: rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, gregkh@linuxfoundation.org, mingo@redhat.com, dietmar.eggemann@arm.com, morten.rasmussen@arm.com, chris.redpath@arm.com, patrick.bellasi@arm.com, valentin.schneider@arm.com, vincent.guittot@linaro.org, thara.gopinath@linaro.org, viresh.kumar@linaro.org, tkjos@google.com, joel@joelfernandes.org, smuckle@google.com, adharmap@codeaurora.org, skannan@codeaurora.org, pkondeti@codeaurora.org, juri.lelli@redhat.com, edubezval@gmail.com, srinivas.pandruvada@linux.intel.com, currojerez@riseup.net, javi.merino@kernel.org Subject: Re: [PATCH v9 13/15] sched/fair: Introduce an energy estimation helper function Message-ID: <20181122135606.GG2113@hirez.programming.kicks-ass.net> References: <20181119141857.8625-1-quentin.perret@arm.com> <20181119141857.8625-14-quentin.perret@arm.com> <20181121142803.GF2113@hirez.programming.kicks-ass.net> <20181121160524.ulj6n3shb2fdwboj@queper01-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181121160524.ulj6n3shb2fdwboj@queper01-lin> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 21, 2018 at 04:05:27PM +0000, Quentin Perret wrote: > On Wednesday 21 Nov 2018 at 15:28:03 (+0100), Peter Zijlstra wrote: > > On Mon, Nov 19, 2018 at 02:18:55PM +0000, Quentin Perret wrote: > > > +static long > > > +compute_energy(struct task_struct *p, int dst_cpu, struct perf_domain *pd) > > > +{ > > > + long util, max_util, sum_util, energy = 0; > > > + int cpu; > > > + > > > + for (; pd; pd = pd->next) { > > > + max_util = sum_util = 0; > > > + /* > > > + * The capacity state of CPUs of the current rd can be driven by > > > + * CPUs of another rd if they belong to the same performance > > > + * domain. So, account for the utilization of these CPUs too > > > + * by masking pd with cpu_online_mask instead of the rd span. > > > + * > > > + * If an entire performance domain is outside of the current rd, > > > + * it will not appear in its pd list and will not be accounted > > > + * by compute_energy(). > > > + */ > > > + for_each_cpu_and(cpu, perf_domain_span(pd), cpu_online_mask) { > > > > Should that not be cpu_active_mask ? > > Hmm, I must admit I'm sometimes a bit confused by the exact difference > between these masks, so maybe yeah ... > > IIUC, cpu_active_mask is basically the set of CPUs on which the > scheduler is actually allowed to migrate tasks. Is that correct ? Yep. Which is a strict subset of online. The difference only matters during hotplug. We take a CPU out of active before we take if offline and we add it to active only after the CPU is fully online and scheduling. > I have always seen cpu_online_mask as a superset of cpu_active_mask > which can also include CPUs which are still running 'special' tasks > (kthreads and things like that I assume) although not allowed for > migration any more (or not yet) because we're in the process of > hotplugging that CPU. Right. > So, the thing is, I'm not trying to select a CPU candidate for my task > here, I'm trying to understand what's the energy impact of a migration. > That involves all CPUs that are running _something_ in a perf domain > no matter if they're allowed to run more tasks or not. I mean, raising > the OPP will make running online && !active CPUs more expensive as well. > That's why I thought cpu_online_mask was good match here. Ah, fair enough. Thanks!