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

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Date:	Wed, 30 Mar 2016 22:12:30 +0200
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:	Doug Smythies <dsmythies@...us.net>,
	Jörg Otte <jrg.otte@...il.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	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

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.

Thanks,
Rafael