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

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Message-ID: <1459352017.13525.45.camel@intel.com>
Date:	Wed, 30 Mar 2016 15:33:21 +0000
From:	"Pandruvada, Srinivas" <srinivas.pandruvada@...el.com>
To:	"jrg.otte@...il.com" <jrg.otte@...il.com>,
	"rafael@...nel.org" <rafael@...nel.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"rjw@...ysocki.net" <rjw@...ysocki.net>
Subject: Re: [intel-pstate driver regression] processor frequency very high
 even if in idle

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>
> wrote:
> > 
> > 2016-03-29 23:34 GMT+02:00 Rafael J. Wysocki <rjw@...ysocki.net>:
> > > 
> > > On Tuesday, March 29, 2016 07:32:27 PM Jörg Otte wrote:
> > > > 
> > > > 2016-03-29 19:24 GMT+02:00 Jörg Otte <jrg.otte@...il.com>:
> > > > > 
> > > > > in v4.5 and earlier intel-pstate downscaled idle processors
> > > > > (load
> > > > > 0.1-0.2%) to minumum frequency, in my case 800MHz.
> > > > > 
> > > > > 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.
> > > > > This is the maximum non turbo frequency.
> > > > > 
> > > > > No difference between powersafe or performance governor.
> > > > > 
> > > > > 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)
> > > > > 
> > > > > Last known good kernel is: 4.5.0-01127-g9256d5a
> > > > > First known bad kernel is: 4.5.0-02535-g09fd671
> > > > > 
> > > > > There is
> > > > > commit 277edba Merge tag 'pm+acpi-4.6-rc1-1' of
> > > > > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
> > > > > in between, which brought a few changes in intel_pstate.
> > > Can you please check commit a4675fbc4a7a (cpufreq: intel_pstate:
> > > Replace timers
> > > with utilization update callbacks)?
> > > 
> > Yes , this solved the problem for me.
> > I had to resolve some conflicts myself when reverting that
> > commit. Hard work :).
> Thanks for doing this.  Can you please post the revert patch you have
> used?
> 
> > 
> > Here is a 10-seconds trace of the used frequencies when
> > in "desktop-idle":
> > 
> > driver          cpu0 cpu1 cpu2 cpu3
> > -------------------------------------
> > intel_pstate (  800  928  941 1200) MHz   load:( 0.2)%
> > intel_pstate (  800  928 1181 1800) MHz   load:( 0.0)%
> > intel_pstate ( 1675 1576 1347  800) MHz   load:( 0.0)%
> > intel_pstate ( 1198 1576  842  800) MHz   load:( 0.5)%
> > intel_pstate (  800 1181 1113 1600) MHz   load:( 0.0)%
> > intel_pstate (  808 1181  805  800) MHz   load:( 0.5)%
> > intel_pstate (  844 1191  900 1082) MHz   load:( 0.3)%
> > intel_pstate (  816 1191  800  800) MHz   load:( 0.0)%
> > intel_pstate (  800  905  892 1082) MHz   load:( 0.2)%
> > intel_pstate (  945  905 1340  800) MHz   load:( 0.3)%
> Please also run turbostat with and without your revert patch applied.
I want to reproduce this if I can. Can you give us info about your
setup (Linux distribution, laptop model etc.)?

Thanks,
Srinivas

> 
> Thanks,
> Rafael
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