From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v10 10/15] sched: Introduce a sysctl for Energy Aware Scheduling Date: Thu, 13 Dec 2018 15:03:58 +0100 Message-ID: <20181213140358.GJ5289@hirez.programming.kicks-ass.net> References: <20181203095628.11858-1-quentin.perret@arm.com> <20181203095628.11858-11-quentin.perret@arm.com> <20181211141509.GA32005@gmail.com> <20181211144901.hio4b6aw3esw3cgw@queper01-lin> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20181211144901.hio4b6aw3esw3cgw@queper01-lin> Sender: linux-kernel-owner@vger.kernel.org To: Quentin Perret Cc: Ingo Molnar , 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 List-Id: linux-pm@vger.kernel.org On Tue, Dec 11, 2018 at 02:49:01PM +0000, Quentin Perret wrote: > Hi Ingo, > > On Tuesday 11 Dec 2018 at 15:15:09 (+0100), Ingo Molnar wrote: > > > > * Quentin Perret wrote: > > > > > In its current state, Energy Aware Scheduling (EAS) starts automatically > > > on asymmetric platforms having an Energy Model (EM). However, there are > > > users who want to have an EM (for thermal management for example), but > > > don't want EAS with it. > > > > Well, then introduce a new Kconfig variant for EAS, if it's super > > important to allow this to be disabled. > > > > Why do we want to disable it - is it not reliable in some circumstances? > > There are people out there using big.little systems who do not care > about energy. Not very many of them, that is true, but they exist. And > those people can be interested in having an Energy Model for > IPA/thermal but also want to spread tasks to minimize latency for > example. So those guys will appreciate a knob, I think. Otherwise EAS > gets enabled/disabled only by side effects (by enabling/disabling > schedutil for example). Right, also we have a sysctl for numa-balancing, I figured having one for eas would not be weird.