From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juri Lelli Subject: Re: [RFCv5 PATCH 40/46] sched/cpufreq_sched: compute freq_new based on capacity_orig_of() Date: Mon, 17 Aug 2015 13:19:59 +0100 Message-ID: <55D1D16F.1070106@arm.com> References: <1436293469-25707-1-git-send-email-morten.rasmussen@arm.com> <1436293469-25707-41-git-send-email-morten.rasmussen@arm.com> <20150815124638.GG10304@worktop.programming.kicks-ass.net> <20150816040333.31346.22542@quantum> <20150816202401.GJ10304@worktop.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Return-path: Received: from eu-smtp-delivery-143.mimecast.com ([207.82.80.143]:28659 "EHLO eu-smtp-delivery-143.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751073AbbHQMTQ convert rfc822-to-8bit (ORCPT ); Mon, 17 Aug 2015 08:19:16 -0400 In-Reply-To: <20150816202401.GJ10304@worktop.programming.kicks-ass.net> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Peter Zijlstra , Michael Turquette Cc: Morten Rasmussen , "mingo@redhat.com" , "vincent.guittot@linaro.org" , "daniel.lezcano@linaro.org" , Dietmar Eggemann , "yuyang.du@intel.com" , "rjw@rjwysocki.net" , "sgurrappadi@nvidia.com" , "pang.xunlei@zte.com.cn" , "linux-kernel@vger.kernel.org" , "linux-pm@vger.kernel.org" On 16/08/15 21:24, Peter Zijlstra wrote: > On Sat, Aug 15, 2015 at 09:03:33PM -0700, Michael Turquette wrote: >> Quoting Peter Zijlstra (2015-08-15 05:46:38) >>> On Tue, Jul 07, 2015 at 07:24:23PM +0100, Morten Rasmussen wrote: >>>> diff --git a/kernel/sched/cpufreq_sched.c b/kernel/sched/cpufreq_sched.c >>>> index 2968f3a..7071528 100644 >>>> --- a/kernel/sched/cpufreq_sched.c >>>> +++ b/kernel/sched/cpufreq_sched.c >>>> @@ -184,7 +184,7 @@ void cpufreq_sched_set_cap(int cpu, unsigned long capacity) >>>> goto out; >>>> >>>> /* Convert the new maximum capacity request into a cpu frequency */ >>>> - freq_new = capacity * policy->max >> SCHED_CAPACITY_SHIFT; >>>> + freq_new = (capacity * policy->max) / capacity_orig_of(cpu); >>>> >>>> /* No change in frequency? Bail and return current capacity. */ >>>> if (freq_new == policy->cur) >>> >>> Can't we avoid exporting that lot by simply passing in the right values >>> to begin with? >> >> By "right value" do you mean, "pass the frequency from cfs"? > > Nah, just maybe: (capacity << SCHED_CAPACITY_SHIFT) / capacity_orig_of() > such that you don't have to export that knowledge to this thing. > Oh, right. I guess we can just go with something like: req_cap = get_cpu_usage(cpu) * capacity_margin / capacity_orig_of(cpu); on fair.c side and switch back to freq_new = capacity * policy->max >> SCHED_CAPACITY_SHIFT; on cpufreq_sched.c side. That saves us exporting capacity_orig_of(). Thanks, - Juri