From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laura Abbott Subject: Re: [REGRESSION] 774ac8b7eff6 ("Thermal: initialize thermal zone device correctly") causes performance drop Date: Wed, 16 Mar 2016 17:00:07 -0700 Message-ID: <56E9F387.9080703@redhat.com> References: <56E9DDED.7000805@redhat.com> <20160316224634.GA3580@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-qg0-f44.google.com ([209.85.192.44]:34988 "EHLO mail-qg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935230AbcCQAAM (ORCPT ); Wed, 16 Mar 2016 20:00:12 -0400 Received: by mail-qg0-f44.google.com with SMTP id y89so59022414qge.2 for ; Wed, 16 Mar 2016 17:00:11 -0700 (PDT) In-Reply-To: <20160316224634.GA3580@kroah.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Greg Kroah-Hartman Cc: Zhang Rui , Javi Merino , Chen Yu , Manuel Krause , szegad , prash , amish , Matthias , linux-pm@vger.kernel.org, Linux Kernel Mailing List On 03/16/2016 03:46 PM, Greg Kroah-Hartman wrote: > On Wed, Mar 16, 2016 at 03:27:57PM -0700, Laura Abbott wrote: >> Hi, >> >> Fedora received a bug report (https://bugzilla.redhat.com/show_bug.cgi?id=1317190) >> of a major performance drop on various bench marks and general system >> sluggishness with the 4.4.4 kernel update. The benchmarks were showing >> a reduction to about 18% performance (not minor). >> >> Bisection showed the first bad commit was >> >> commit 774ac8b7eff69e0786970157de2157e68b22f456 >> Author: Zhang Rui >> Date: Fri Oct 30 16:31:47 2015 +0800 >> >> Thermal: initialize thermal zone device correctly >> commit bb431ba26c5cd0a17c941ca6c3a195a3a6d5d461 upstream. >> After thermal zone device registered, as we have not read any >> temperature before, thus tz->temperature should not be 0, >> which actually means 0C, and thermal trend is not available. >> In this case, we need specially handling for the first >> thermal_zone_device_update(). >> Both thermal core framework and step_wise governor is >> enhanced to handle this. And since the step_wise governor >> is the only one that uses trends, so it's the only thermal >> governor that needs to be updated. >> Tested-by: Manuel Krause >> Tested-by: szegad >> Tested-by: prash >> Tested-by: amish >> Tested-by: Matthias >> Reviewed-by: Javi Merino >> Signed-off-by: Zhang Rui >> Signed-off-by: Chen Yu >> Signed-off-by: Greg Kroah-Hartman >> >> >> >> Reverting this plus to other commits in the series (a67208e94d94 >> "Thermal: handle thermal zone device properly during system sleep" >> and 27f356149d59 "Thermal: do thermal zone update after a cooling >> device registered") confirmed the performance was back to normal. >> >> Bugzilla has the full discussion but this comment from one of the >> reporters sums it up: >> >> "In 4.4.3 and prior, my 2.40 MHz processor would fluctuate between >> 1000 and 3400 MHz. In 4.4.4, the processor would fluctuate between >> 400 and 700 MHz, according to /proc/cpuinfo. >> >> Setting /sys/devices/system/cpu/cpufreq/policy0/scaling_governor to >> performance, instead of the default "powersave" forces the CPU to >> 2400 MHz, and improves performance greatly, but still not to the >> same level as in 4.4.3." >> >> Any ideas? > > Is this same "slowdown" also seen in 4.5? > > thanks, > > greg k-h > Yes, the same issue is seen on 4.5 according to the reporter. Thanks, Laura