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

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Date:	Fri, 1 Apr 2016 02:08:31 +0200
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Jörg Otte <jrg.otte@...il.com>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Doug Smythies <dsmythies@...us.net>
Subject: Re: [intel-pstate driver regression] processor frequency very high
 even if in idle

On Thu, Mar 31, 2016 at 7:55 PM, Srinivas Pandruvada
<srinivas.pandruvada@...ux.intel.com> wrote:
> On Thu, 2016-03-31 at 19:27 +0200, Jörg Otte wrote:
>> 2016-03-31 17:43 GMT+02:00 Rafael J. Wysocki <rjw@...ysocki.net>:
>> > On Thursday, March 31, 2016 05:25:18 PM Jörg Otte wrote:
>> > > 2016-03-31 13:42 GMT+02:00 Rafael J. Wysocki <rjw@...ysocki.net>:
>> > > > On Thursday, March 31, 2016 11:05:56 AM Jörg Otte wrote:
>> > > >

[cut]

>>
>> OK, patch is applied.
>> After some configurations and compilations I'm there.
>> Under pstate_sample I see:
>> enable  filter  format  id  trigger
>>
>> what to do now ? (never did tracing before)'
>
> # cd /sys/kernel/debug/tracing/
> # echo 1 > events/power/pstate_sample/enable
> # echo 1 > events/power/cpu_frequency/enable
> # cat trace
> Send us the trace file.

Here's what I do, for completeness:

# echo 0 > /sys/kernel/debug/tracing/tracing_on
# echo global > /sys/kernel/debug/tracing/trace_clock
# echo nop > /sys/kernel/debug/tracing/current_tracer
# echo 1000 > /sys/kernel/debug/tracing/buffer_size_kb
# echo 1 > /sys/kernel/debug/tracing/events/power/pstate_sample/enable
# echo "" > /sys/kernel/debug/tracing/trace
# echo 1 > /sys/kernel/debug/tracing/tracing_on

Then, (after a while) make a copy of the trace file.