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

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Date:	Wed, 30 Mar 2016 13:26:27 -0700
From:	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
Cc:	Doug Smythies <dsmythies@...us.net>,
	Jörg Otte <jrg.otte@...il.com>,
	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, 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. 

Thanks,
Srinivas

> Thanks,
> Rafael
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