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

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Date:	Wed, 30 Mar 2016 11:58:56 -0700
From:	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:	Doug Smythies <dsmythies@...us.net>,
	'Jörg Otte' <jrg.otte@...il.com>
Cc:	rafael@...nel.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, rjw@...ysocki.net
Subject: Re: [intel-pstate driver regression] processor frequency very high
 even if in idle

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.

Thanks,
Srinivas