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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 27366C606AC for ; Mon, 8 Jul 2019 11:13:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E75F020665 for ; Mon, 8 Jul 2019 11:13:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730311AbfGHLNx (ORCPT ); Mon, 8 Jul 2019 07:13:53 -0400 Received: from foss.arm.com ([217.140.110.172]:45042 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730294AbfGHLNx (ORCPT ); Mon, 8 Jul 2019 07:13:53 -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 4C85B360; Mon, 8 Jul 2019 04:13:52 -0700 (PDT) Received: from e110439-lin (e110439-lin.cambridge.arm.com [10.1.194.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 123B63F738; Mon, 8 Jul 2019 04:13:50 -0700 (PDT) Date: Mon, 8 Jul 2019 12:13:49 +0100 From: Patrick Bellasi To: Douglas Raillard Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, mingo@redhat.com, rjw@rjwysocki.net, viresh.kumar@linaro.org, quentin.perret@arm.com, dietmar.eggemann@arm.com Subject: Re: [RFC PATCH v2 0/5] sched/cpufreq: Make schedutil energy aware Message-ID: <20190708111348.o6o63jisbukuk64d@e110439-lin> References: <20190627171603.14767-1-douglas.raillard@arm.com> <20190702154422.GV3436@hirez.programming.kicks-ass.net> <590e3dd9-ea4e-5230-d12c-d04bb3916e89@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <590e3dd9-ea4e-5230-d12c-d04bb3916e89@arm.com> User-Agent: NeoMutt/20180716 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 03-Jul 14:38, Douglas Raillard wrote: > Hi Peter, > > On 7/2/19 4:44 PM, Peter Zijlstra wrote: > > On Thu, Jun 27, 2019 at 06:15:58PM +0100, Douglas RAILLARD wrote: > > > Make schedutil cpufreq governor energy-aware. > > > > > > - patch 1 introduces a function to retrieve a frequency given a base > > > frequency and an energy cost margin. > > > - patch 2 links Energy Model perf_domain to sugov_policy. > > > - patch 3 updates get_next_freq() to make use of the Energy Model. > > > > > > > > 1) Selecting the highest possible frequency for a given cost. Some > > > platforms can have lower frequencies that are less efficient than > > > higher ones, in which case they should be skipped for most purposes. > > > They can still be useful to give more freedom to thermal throttling > > > mechanisms, but not under normal circumstances. > > > note: the EM framework will warn about such OPPs "hertz/watts ratio > > > non-monotonically decreasing" > > > > Humm, for some reason I was thinking we explicitly skipped those OPPs > > and they already weren't used. > > > > This isn't in fact so, and these first few patches make it so? > > That's correct, the cost information about each OPP has been introduced recently in mainline > by the energy model series. Without that info, the only way to skip them that comes to my > mind is to set a policy min frequency, since these inefficient OPPs are usually located > at the lower end. Perhaps it's also worth to point out that the alternative approach you point out above is a system wide solution. While, the ramp_boost thingy you propose, it's a more fine grained mechanisms which could be extended in the future to have a per-task side. IOW, it could contribute to have better user-space hints, for example to ramp_boost more certain tasks and not others. Best, Patrick -- #include Patrick Bellasi