From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stratos Karafotis Subject: Re: [PATCH 2/2] cpufreq: ondemand: Eliminate the deadband effect Date: Fri, 11 Jul 2014 20:29:57 +0300 Message-ID: <53C01F15.2090702@semaphore.gr> References: <1404147574-17422-1-git-send-email-stratosk@semaphore.gr> <1404147574-17422-3-git-send-email-stratosk@semaphore.gr> <20140711165710.GA18033@amd.pavel.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from sema.semaphore.gr ([78.46.194.137]:60019 "EHLO sema.semaphore.gr" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752072AbaGKRaA (ORCPT ); Fri, 11 Jul 2014 13:30:00 -0400 In-Reply-To: <20140711165710.GA18033@amd.pavel.ucw.cz> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Pavel Machek Cc: rjw@rjwysocki.net, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Hi Pavel! On 11/07/2014 07:57 =CE=BC=CE=BC, Pavel Machek wrote: > Hi! >=20 >> Tested on Intel i7-3770 CPU @ 3.40GHz and on ARM quad core 1500MHz K= rait >> (Android smartphone). >> Benchmarks on Intel i7 shows a performance improvement on low and me= dium >> work loads with lower power consumption. Specifics: >> >> Phoronix Linux Kernel Compilation 3.1: >> Time: -0.40%, energy: -0.07% >> Phoronix Apache: >> Time: -4.98%, energy: -2.35% >> Phoronix FFMPEG: >> Time: -6.29%, energy: -4.02% >=20 > Hmm. Intel i7 should be race-to-idle machine. So basically rule like > if (load > 0) go to max frequency else go to lowest frequency would d= o > the right thing in your test, right? I don't think that "if (load > 0) go to max" will work even on i7. =46or low load this will have impact on energy consumption. On my tests, a simple mp3 decoding (very low load on my machine) have n= o difference with and without this patch. > So... should we do that, or do we need better benchmark? I'm sorry. I'm not sure I understood exactly what do you mean by "bette= r benchmark". Of course, we should do as many benchmarks as we can. I usually do these 5 sets of benchmarks on my i7 that IMHO give a good indication about the changes in different CPU loads. 1) Linux kernel compilation (about 85% busy CPU) 2) Apache (about 32% busy CPU) 3) ffmpeg (about 24% busy CPU) 4) mp3 decoding (about 0.3% CPU) 5) Idle system (about 0.06% CPU) The patch was also tested on a Android smartphone (kernel 3.4). The ker= nel distributed to 1000+ users. Unfortunately I have no benchmarks, but no regressions reported on consumption. Actually, there reports for better performance and lower power consumption, but of course we can't rely on these reports. = :) Thanks for your comments! Stratos