From mboxrd@z Thu Jan 1 00:00:00 1970 From: Srinivas Pandruvada Subject: Re: Regression in 4.8 - CPU speed set very low Date: Mon, 26 Sep 2016 18:30:46 -0700 Message-ID: <1474939846.4669.96.camel@linux.intel.com> References: <3919370.SGLjGupePs@vostro.rjw.lan> <075788ab-34e0-803c-f2b4-3f370ecc6b14@lwfinger.net> <2477506.olat0BX4ex@vostro.rjw.lan> <1436996d-078b-aa51-4452-b6655d917135@lwfinger.net> <594f5012-5157-bfdd-f715-bea8caa824c3@lwfinger.net> <2326a7dd-675f-752b-f100-5dce6e4c93fd@lwfinger.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: Received: from mga03.intel.com ([134.134.136.65]:45260 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932504AbcI0Bd3 (ORCPT ); Mon, 26 Sep 2016 21:33:29 -0400 In-Reply-To: <2326a7dd-675f-752b-f100-5dce6e4c93fd@lwfinger.net> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Larry Finger , "Rafael J. Wysocki" Cc: "Rafael J. Wysocki" , LKML , Linux PM list On Mon, 2016-09-26 at 19:48 -0500, Larry Finger wrote: > On 09/26/2016 07:21 PM, Rafael J. Wysocki wrote: > > > > On Tue, Sep 27, 2016 at 1:53 AM, Larry Finger > r.net> wrote: > > > > > > On 09/26/2016 05:16 PM, Rafael J. Wysocki wrote: > > > > > > > > > > > > On Tue, Sep 27, 2016 at 12:09 AM, Larry Finger > > > wrote: > > > > > > > > > > > > > > > > Maybe it's better to try diagnose the problem instead of > > > > spending more > > > > time on bisection. > > > > > > In my original post, I asked for such help, but nothing until > > > today. I had > > > no idea what to check, but now I have a better idea. > > > > > > > > > > > I'd like to know whether or not 4.7 was definitely good, > > > > though. > > > > > > I never saw this problem with 4.7, but given the difficulty in > > > triggering > > > the problem, my tests may not have been definitive. > > > > > > > > > > > > > > > > > > > > > > If it is one of them, it may be a while before I dare call > > > > > this one > > > > > "good". > > > > > In one respect, that is good as I will be traveling tomorrow > > > > > and > > > > > Wednesday. > > > > > > > > What does "cat > > > > /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver" say? > > > > > > intel_pstate > > You probably don't need to worry about all of the cpufreq changes > > in > > 4.8-rc, then.  Only a few of them affect intel_pstate and I don't > > see > > how any of them may lead to the observed symptoms. > > > > First off, if you have a reproducer, please run it on 4.7 and see > > if > > you can trigger the issue in there. > I'm running 4.8-rc7 at the moment hoping to trigger the problem and > get the data  > requested by Srinivas. Once I get that, I will try 4.7 again. > > > > > > Second, it would be good to have a look at the output from the > > cpu_frequency and pstate_sample tracepoints around when the issue > > triggers.  The pstate_sample one would be more interesting. > > > > But for both we need a reproducer anyway. > I do not have a reliable reproducer. The condition has always > happened when  > running a high-compute job such as a 'make -j8' on the kernel, or > building the  > RPM for openSUSE's implementation of VirtualBox. The latter is what > I'm using  > for most of my testing. > > > > > It also would be good to rule out the thermal throttling (as per > > the > > Srinivas' comments). > > > > For now, please tell me what's in > > /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq > 800000 Your effective freq is lower than 800MHz. One of the possible reason is thermal throttling. What distro you are using? Thanks, Srinivas