From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [RFC][PATCH 6/7] cpufreq: schedutil: Add iowait boosting Date: Wed, 03 Aug 2016 01:03:23 +0200 Message-ID: <1808398.B5hOCmgoWi@vostro.rjw.lan> References: <3752826.3sXAQIvcIA@vostro.rjw.lan> <1572483.euTsoFDNE9@vostro.rjw.lan> <20160802013531.GC9332@graphite.smuckle.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: Received: from cloudserver094114.home.net.pl ([79.96.170.134]:58258 "HELO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756546AbcHBW6N (ORCPT ); Tue, 2 Aug 2016 18:58:13 -0400 In-Reply-To: <20160802013531.GC9332@graphite.smuckle.net> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Steve Muckle Cc: Linux PM list , Peter Zijlstra , Srinivas Pandruvada , Viresh Kumar , Linux Kernel Mailing List , Juri Lelli , Ingo Molnar On Monday, August 01, 2016 06:35:31 PM Steve Muckle wrote: > On Mon, Aug 01, 2016 at 01:37:59AM +0200, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki > > > > Modify the schedutil cpufreq governor to boost the CPU frequency > > if the UUF_IO flag is passed to it via cpufreq_update_util(). > > > > If that happens, the frequency is set to the maximum during > > the first update after receiving the UUF_IO flag and then the > > boost is reduced by half during each following update. > > Were these changes to schedutil part of the positive test results > mentioned in patch 5? Or are those just from intel pstate? > > I was nervous about the effect of this on power and tested a couple low > power usecases. The platform is the Hikey 96board (8 core ARM A53, > single CPUfreq domain) running AOSP Android and schedutil backported to > kernel 4.4. These tests run mp3 and mpeg4 playback for a little while, > recording total energy consumption during the test along with frequency > residency. > > As the results below show I did not measure an appreciable effect - if > anything things may be slightly better with the patches. > > The hardcoding of a non-tunable boosting scheme makes me nervous but > perhaps it could be revisited if some platform or configuration shows > a noticeable regression? That would be my approach. :-) I'm not a big fan of tunables in general, as there are only a few people who actually set them to anything different from the default and then they get a lot of focus (even though they are after super-corner cases sometimes). Thanks, Rafael