From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755458AbcI0CxO (ORCPT ); Mon, 26 Sep 2016 22:53:14 -0400 Received: from mail-oi0-f54.google.com ([209.85.218.54]:35366 "EHLO mail-oi0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752793AbcI0CxM (ORCPT ); Mon, 26 Sep 2016 22:53:12 -0400 Subject: Re: Regression in 4.8 - CPU speed set very low To: Srinivas Pandruvada , "Rafael J. Wysocki" 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> <1474939846.4669.96.camel@linux.intel.com> Cc: "Rafael J. Wysocki" , LKML , Linux PM list From: Larry Finger Message-ID: Date: Mon, 26 Sep 2016 21:53:10 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <1474939846.4669.96.camel@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/26/2016 08:30 PM, Srinivas Pandruvada wrote: > 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? openSUSE Leap 42.1. Larry