Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753398AbdLVMUG (ORCPT ); Fri, 22 Dec 2017 07:20:06 -0500 Received: from merlin.infradead.org ([205.233.59.134]:46672 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750961AbdLVMUE (ORCPT ); Fri, 22 Dec 2017 07:20:04 -0500 Date: Fri, 22 Dec 2017 13:19:54 +0100 From: Peter Zijlstra To: Patrick Bellasi Cc: Juri Lelli , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Ingo Molnar , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Dietmar Eggemann , Morten Rasmussen , Todd Kjos , Joel Fernandes Subject: Re: [PATCH v3 0/6] cpufreq: schedutil: fixes for flags updates Message-ID: <20171222121954.x3vgj7s6infdox46@hirez.programming.kicks-ass.net> References: <20171130114723.29210-1-patrick.bellasi@arm.com> <20171220153029.dqrtjbyowhqdl56r@hirez.programming.kicks-ass.net> <20171220173814.GC22246@localhost.localdomain> <20171222100626.7g5yklspjofcp2we@hirez.programming.kicks-ass.net> <20171222110206.GA6414@e110439-lin> <20171222114618.mlbqdbagrbr7oert@hirez.programming.kicks-ass.net> <20171222120737.GA30968@e110439-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171222120737.GA30968@e110439-lin> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1455 Lines: 32 On Fri, Dec 22, 2017 at 12:07:37PM +0000, Patrick Bellasi wrote: > > I was thinking that since dl is a 'global' scheduler the reservation > > would be too and thus the freq just needs a single CPU to be observed; > > AFAIU global is only the admission control (which is something worth a > thread by itself...) while the dl_se->dl_bw are aggregated into the > dl_rq->running_bw, which ultimately represents the DL bandwidth > required for just a CPU. Oh urgh yes, forgot that.. then the dl freq stuff isn't strictly correct I think. But yes, that's another thread. > > but I suppose there's nothing stopping anybody from splitting a clock > > domain down the middle scheduling wise. So yes, good point. > > That makes sense... moreover, using the global utilization, we would > end up asking for capacities which cannot be provided by a single CPU. Yes, but that _should_ not be a problem if you clock them all high enough. But this gets to be complicated real fast I think. > > Blergh that'd make a mess of things again. > > Actually, looking better at your patch: are we not just ok with that? > > I mean, we don't need this check on idle_cpu since in > sugov_aggregate_util we already skip the util=sg_cpu->max in case of > !rq->rt.rt_nr_running, while we aggregate just CFS and DL requests. Right, well, I don't actually have an environment to test this sanely, so someone will have to go play with the various variations and see what works.