linux-kernel - Re: [intel-pstate driver regression] processor frequency very high even if in idle

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Date:	Thu, 31 Mar 2016 11:23:33 +0200
From:	Jörg Otte <jrg.otte@...il.com>
To:	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:	"Rafael J. Wysocki" <rafael@...nel.org>,
	Doug Smythies <dsmythies@...us.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [intel-pstate driver regression] processor frequency very high
 even if in idle

2016-03-30 22:26 GMT+02:00 Srinivas Pandruvada
<srinivas.pandruvada@...ux.intel.com>:
> On Wed, 2016-03-30 at 22:12 +0200, Rafael J. Wysocki wrote:
>> On Wed, Mar 30, 2016 at 8:58 PM, Srinivas Pandruvada
>> <srinivas.pandruvada@...ux.intel.com> wrote:
>> >
>> > On Wed, 2016-03-30 at 11:50 -0700, Doug Smythies wrote:
>> > >
>> > > On 2016.03.30 08:52 Jörg Otte wrote:
>> > > >
>> > > >
>> > > > 2016-03-30 17:33 GMT+02:00 Pandruvada, Srinivas
>> > > > <srinivas.pandruvad
>> > > > a@...el.com>:
>> > > > >
>> > > > >
>> > > > > On Wed, 2016-03-30 at 13:05 +0200, Rafael J. Wysocki wrote:
>> > > > > >
>> > > > > >
>> > > > > > On Wed, Mar 30, 2016 at 12:17 PM, Jörg Otte <jrg.otte@...il
>> > > > > > .com
>> > > > > > >
>> > > > > > >
>> > > > >
>> > > > >
>> > > > > >
>> > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > > > >
>> > > > > > > >
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > Now in v4.6-rc1 the characteristic has dramatically
>> > > > > > > > > changed.
>> > > > > > > > > If in idle the processor frequency is more or less a
>> > > > > > > > > few
>> > > > > > > > > MHz around 2500Mhz.
>> > > > > > > > > I currently use acpi_cpufreq which works as usual.
>> > > > > > > > > Processor: Intel(R) Core(TM) i5-4200M CPU @ 2.50GHz
>> > > > > > > > > (family: 0x6, model: 0x3c, stepping: 0x3)
>> > > > >
>> > > > >
>> > > > > I want to reproduce this if I can. Can you give us info about
>> > > > > your
>> > > > > setup (Linux distribution, laptop model etc.)?
>> > > I would like to try to reproduce the issue also.
>> > >
>> > > >
>> > > >
>> > > > Distro: Ubuntu 14.04.4 LTS
>> > > Note that with Ubuntu 14.04, I had issues where my CPU
>> > > would lock at pstate 24 (not always 24, but usually),
>> > > regardless of load.
>> > > However, it was always after an S3 suspend, occurred 100%
>> > > of the time, and was independent of intel_pstate or
>> > > acpi-cpufreq CPU frequency scaling drivers.
>> > >
>> > > Since changing my test server to Ubuntu server edition 16.04
>> > > (development version), I have not had those issues. While I have
>> > > no proof, I have assumed the issue elimination was somehow
>> > > related
>> > > to the change to systemd.
>> > >
>> > > It might be worth observing both what the intel_pstate is asking
>> > > for
>> > > and what the processor is actually doing.
>> > If Jörg runs with
>> >
>> > turbostat -i 1 --msr=0x199
>> >
>> > We can tell whether if we requested or the same problem you had.
>> > I tried on Ubuntu LTS 14.04 on same Haswell CPU model, I didn't see
>> > this issue.
>> There seems to be something odd about the Jörg's setup, or we'd have
>> received more reports about this issue.
>>
>> Question is what that is and what really makes the difference.
>>
> I think, somehow we entered performance mode from powersave by default
>
> turbostat -i 1 --msr=0x199 will tell us.
>

jojo@...hte:/sys/devices/system/cpu/cpufreq/policy0$ cat scaling_governor
powersave

turbostat -i 1 --msr=0x199
CPUID(7): No-SGX
     CPU Avg_MHz   Busy% Bzy_MHz TSC_MHz   MSR 0x199
       -      45    1.74    2590    2496  0x00000000
       0      45    1.76    2565    2498  0x00000a00
       1      72    2.84    2548    2496  0x00000800
       2      30    1.11    2661    2496  0x00001a00
       3      33    1.23    2661    2495  0x00001a00
     CPU Avg_MHz   Busy% Bzy_MHz TSC_MHz   MSR 0x199
       -       9    0.35    2525    2495  0x00000000
       0       1    0.04    2735    2495  0x00000800
       1       1    0.05    2501    2495  0x00000800
       2      17    0.65    2540    2495  0x00001a00
       3      16    0.64    2501    2495  0x00001a00
     CPU Avg_MHz   Busy% Bzy_MHz TSC_MHz   MSR 0x199
       -      11    0.43    2523    2495  0x00000000
       0       3    0.11    2631    2495  0x00000c00
       1       7    0.27    2524    2495  0x00000800
       2      18    0.72    2527    2495  0x00001a00
       3      15    0.61    2501    2495  0x00001a00

Thanks, Jörg