Re: PROBLEM: Cpufreq constantly keeps frequency at maximum on 4.5-rc4

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On 02/21/2016 12:52 AM, Chen, Yu C wrote:
>> -----Original Message-----
>> From: Arto Jantunen [mailto:viiru@iki.fi]
>> Sent: Sunday, February 21, 2016 4:45 PM
>> To: Chen, Yu C
>> Cc: Doug Smythies; 'Rafael J. Wysocki'; 'Viresh Kumar'; linux-
>> pm@vger.kernel.org; 'Srinivas Pandruvada'
>> Subject: Re: PROBLEM: Cpufreq constantly keeps frequency at maximum on
>> 4.5-rc4
>>
>> "Chen, Yu C" <yu.c.chen@intel.com> writes:
>>
>>>> -----Original Message-----
>>>> From: linux-pm-owner@vger.kernel.org [mailto:linux-pm-
>>>> owner@vger.kernel.org] On Behalf Of Arto Jantunen
>>>> Sent: Sunday, February 21, 2016 1:11 AM
>>>> To: Doug Smythies
>>>> Cc: 'Rafael J. Wysocki'; 'Viresh Kumar'; linux-pm@vger.kernel.org;
>>>> 'Srinivas Pandruvada'
>>>> Subject: Re: PROBLEM: Cpufreq constantly keeps frequency at maximum
>>>> on
>>>> 4.5-rc4
>>>>
>>>> "Doug Smythies" <dsmythies@telus.net> writes:
>>>>
>>>>> On 2106.02.20 00:50 Arto Jantunen wrote:
>>>>>> I can force the frequency down manually with cpufreq-set, so the
>>>>>> problem doesn't seem to be with the actual frequency changing.
>>>   cpufreq-set modifies the value of scaling_max_freq, it looks like
>>> your system always demands for the max freq, can you provide:
>>> grep . /sys/devices/system/cpu/intel_pstate/*perf_pct
>>> under powersave and performance?
>> Powersave:
>> /sys/devices/system/cpu/intel_pstate/max_perf_pct:100
>> /sys/devices/system/cpu/intel_pstate/min_perf_pct:22
>>
>> Performance:
>> /sys/devices/system/cpu/intel_pstate/max_perf_pct:100
>> /sys/devices/system/cpu/intel_pstate/min_perf_pct:100
>>
>> Also, adding intel_pstate=no_hwp to the command line does not change the
>> result. Changing that to intel_pstate=disable does fix the problem, so the
>> bug seems to be somewhere in intel_pstate instead of cpufreq core.
You have Skylake, which is not compatible with legacy ACPI P states with 
_PSS tables, so not running without intel_pstate is not much use. It may 
be running at at low P-state by disabling.

Is Debian use default mode as performance? I think Ubuntu uses 
performance mode as default.
What is the output of
cat cpu*/cpufreq/scaling_governor

Thanks,
Srinivas
> 1.It would be nice if a git bisect is used to find the commit causing this problem.
>
> 2.
> # cd /sys/kernel/debug/tracing/
> # echo 1 > events/power/pstate_sample/enable
> # echo 1 > events/power/cpu_frequency/enable
> # cat trace
>