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=-5.3 required=3.0 tests=BAYES_00, 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 A1724C4727E for ; Thu, 24 Sep 2020 16:08:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5E32723600 for ; Thu, 24 Sep 2020 16:08:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728559AbgIXQIt (ORCPT ); Thu, 24 Sep 2020 12:08:49 -0400 Received: from foss.arm.com ([217.140.110.172]:50000 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728448AbgIXQIt (ORCPT ); Thu, 24 Sep 2020 12:08:49 -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 91D601396; Thu, 24 Sep 2020 09:08:48 -0700 (PDT) Received: from localhost (unknown [10.1.199.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 329063F718; Thu, 24 Sep 2020 09:08:48 -0700 (PDT) Date: Thu, 24 Sep 2020 17:08:46 +0100 From: Ionela Voinescu To: Quentin Perret Cc: mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, catalin.marinas@arm.com, will@kernel.org, rjw@rjwysocki.net, viresh.kumar@linaro.org, dietmar.eggemann@arm.com, valentin.schneider@arm.com, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/3] condition EAS enablement on FI support Message-ID: <20200924160846.GB17927@arm.com> References: <20200924123937.20938-1-ionela.voinescu@arm.com> <20200924133727.GB3920949@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200924133727.GB3920949@google.com> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 24 Sep 2020 at 14:37:27 (+0100), Quentin Perret wrote: > On Thursday 24 Sep 2020 at 13:39:34 (+0100), Ionela Voinescu wrote: > > Given the maturity gained by cpufreq-based Frequency Invariance (FI) > > support following the patches at [1], this series conditions Energy > > Aware Scheduling (EAS) enablement on a frequency invariant system. > > > > Currently, EAS can be enabled on a system without FI support, leading > > to incorrect (energy-wise) task placements. As no warning is emitted, > > it could take some debugging effort to track the behavior back to the > > lack of FI support; this series changes that by disabling EAS > > (and advertising it) when FI support is missing. > > > > The series is structured as follows: > > - 1/3 - create function that can rebuild the scheduling and EAS' > > performance domains if EAS' initial conditions change > > - 2/3 - condition EAS enablement on FI support > > - 3/3 - arm64: rebuild scheduling and performance domains in the > > case of late, counter-driven FI initialisation. > > I'm still reading through this, but shouldn't patch 2 and 3 be swapped? > Otherwise we have a weird state at patch 2 where EAS will fail to start > (IIUC), which might not be ideal for bisection. > > Thoughts? I probably invented myself reasons for not doing it, like: without 2/3, 3/3 does not make any sense having and the scenario at 3/3 is currently unlikely. But it would definitely make it safer, so I'll change the order. Thanks, Ionela. > > Cheers, > Quentin