From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v5 10/14] sched/cpufreq: Refactor the utilization aggregation method Date: Thu, 2 Aug 2018 19:36:01 +0200 Message-ID: <20180802173601.GO2494@hirez.programming.kicks-ass.net> References: <20180724122521.22109-1-quentin.perret@arm.com> <20180724122521.22109-11-quentin.perret@arm.com> <331552975e858911db66bc78c2c8e720@codeaurora.org> <20180802123315.GV2476@hirez.programming.kicks-ass.net> <20180802124511.GN2512@hirez.programming.kicks-ass.net> <20180802152109.2k45jqbfquef6u62@queper01-lin> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20180802152109.2k45jqbfquef6u62@queper01-lin> Sender: linux-kernel-owner@vger.kernel.org To: Quentin Perret Cc: skannan@codeaurora.org, 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@quicinc.com, skannan@quicinc.com, pkondeti@codeaurora.org, juri.lelli@redhat.com, edubezval@gmail.com, srinivas.pandruvada@linux.intel.com, currojerez@riseup.net, javi.merino@kernel.org, linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org On Thu, Aug 02, 2018 at 04:21:11PM +0100, Quentin Perret wrote: > On Thursday 02 Aug 2018 at 14:45:11 (+0200), Peter Zijlstra wrote: > > To clarify, it makes absolutely no sense what so ever to attempt EAS > > when the DVFS control is not coordinated. > > I tend to agree with that, but at the same time even if we create a very > strong dependency on schedutil, we will have no guarantee that the actual > frequencies used on the platform are the ones we predicted in EAS. Sure; on x86 for example our micro-code does whatever. But using schedutil we at least 'guide' it in the general direction we'd expect with the control that is available. Using a !schedutil governor doesn't even get us that and we're basically running on random input without any feedback to close the loop. Not something I feel we should support or care for.