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

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Date:	Thu, 31 Mar 2016 01:25:23 +0200
From:	Sedat Dilek <sedat.dilek@...il.com>
To:	"Pandruvada, Srinivas" <srinivas.pandruvada@...el.com>
Cc:	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	"dsmythies@...us.net" <dsmythies@...us.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"jrg.otte@...il.com" <jrg.otte@...il.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"rafael@...nel.org" <rafael@...nel.org>
Subject: Re: [intel-pstate driver regression] processor frequency very high
 even if in idle

On Thu, Mar 31, 2016 at 1:17 AM, Pandruvada, Srinivas
<srinivas.pandruvada@...el.com> wrote:
> On Wed, 2016-03-30 at 15:46 -0700, Srinivas Pandruvada wrote:
>> On Thu, 2016-03-31 at 00:25 +0200, Rafael J. Wysocki wrote:
>> >
>> > On 3/31/2016 12:18 AM, Srinivas Pandruvada wrote:
>> > >
>> > >
>> > > On Wed, 2016-03-30 at 23:41 +0200, Sedat Dilek wrote:
>> > > >
>> > > >
>> > > > Hi,
>> > > >
>> > > > I am using Intel-PState-Driver here with v4.6-rc1 and Intel-
>> > > > SandyBridge-CPU.
>> > > >
>> > > > Here are my turbostat results attached.
>> > > >
>> > > > $ cd $BUILD_DIR
>> > > > $ LC_ALL=C make -C tools/ turbostat
>> > > >
>> > > > $ sudo ./turbostat -i 1 --msr=0x199 --debug --out
>> > > > /tmp/turbostat-i-1-msr-0x199-debug.txt
>> > > >
>> > > > Will try <https://patchwork.kernel.org/patch/8702071/>.
>> > > >
>> > > > Please see attached files.
>> > > >
>> > > Thanks. Your logs make sense. You have config set to performance
>> > > mode
>> > > by default (Which I believe default in all kernel Ubuntu). So as
>> > > expected Intel P state was asking for max. So there is no issue
>> > > here.
>> > But the behavior is different from what it used to be, isn't it?
>> >
>> There are two turbostat output files, In both I see we are requesting
>> max (0x1700) in performance mode. This CPU is Sandybridge, so no
>> config
>> TDP here, the other problem system reported is Haswell
>> .
>>  0       1       3    0.15    2017    1596  0x00001700
>>
>> I am not sure whether Sedat is saying that he has the same issue as
>> Jorg. I think Sedat will see the same turbostat output if he ran 4.5.
>>
> I takeback my statements. It will depend on when he ran turbostat, is
> it within a minute or so. As doug suggested, ubuntu changes the mode to
> powersave, then we shouldn't see 0x1700 in MSR 0x199.
> Sedat,
> What is the output of
> cat /sys/devices/system/cpu/cpu?/cpufreq/scaling_governor
>
> Thanks,
> Srinivas
>
>> Sedat,
>> Please confirm whether you see difference between 4.5 and 4.6-rc1.
>>
>> Thanks,
>> Srinivas
>>
>> >
>> > So there seems to be a problem here AFAICS.

Too much questions.

I switched to CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE=y and tested with
the simplified revert-patch of Rafael.

$ cat /sys/devices/system/cpu/cpu?/cpufreq/scaling_governor
powersave
powersave
powersave
powersave

Bzy_MHz and MSR 0x199 looks OK in my turbostat output?

- Sedat -

View attachment "turbostat-i-1-msr-0x199-debug_4.6.0-rc1-13-iniza-small.txt" of type "text/plain" (30052 bytes)

Download attachment "config-4.6.0-rc1-13-iniza-small" of type "application/octet-stream" (134944 bytes)

View attachment "dmesg_4.6.0-rc1-13-iniza-small.txt" of type "text/plain" (61787 bytes)