Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756586AbdLVMHu (ORCPT ); Fri, 22 Dec 2017 07:07:50 -0500 Received: from foss.arm.com ([217.140.101.70]:45628 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756335AbdLVMHp (ORCPT ); Fri, 22 Dec 2017 07:07:45 -0500 Date: Fri, 22 Dec 2017 12:07:37 +0000 From: Patrick Bellasi To: Peter Zijlstra 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: <20171222120737.GA30968@e110439-lin> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171222114618.mlbqdbagrbr7oert@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1936 Lines: 50 On 22-Dec 12:46, Peter Zijlstra wrote: > On Fri, Dec 22, 2017 at 11:02:06AM +0000, Patrick Bellasi wrote: > > > @@ -315,8 +315,8 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time) > > > unsigned long j_util, j_max; > > > s64 delta_ns; > > > > > > - if (j_sg_cpu != sg_cpu) > > > - sugov_get_util(j_sg_cpu); > > > + if (idle_cpu(j)) > > > + continue; > > > > That should work to skip IDLE CPUs... however I'm missing where now we > > get the sugov_get_util(j_sg_cpu) for active CPUs. It has been moved > > somewhere else I guess... > > No, I'm just an idiot... lemme fix that. Then you just missed a call to sugov_get_util(j_sg_cpu) after the above if... right, actually that was Viresh proposal... > > Moreover, that way don't we completely disregard CFS blocked load for > > IDLE CPUs... as well as DL reserved utilization, which should be > > released only at the 0-lag time? > > 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. > 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. > 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. -- #include Patrick Bellasi