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

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Date:	Sun, 3 Apr 2016 11:59:51 -0700
From:	"Doug Smythies" <dsmythies@...us.net>
To:	<sedat.dilek@...il.com>
Cc:	"'Srinivas Pandruvada'" <srinivas.pandruvada@...ux.intel.com>,
	"'Rafael J. Wysocki'" <rafael.j.wysocki@...el.com>,
	"'Linux PM list'" <linux-pm@...r.kernel.org>,
	"'LKML'" <linux-kernel@...r.kernel.org>,
	'Jörg Otte' <jrg.otte@...il.com>
Subject: RE: [intel-pstate driver regression] processor frequency very high even if in idle

On 2016.04.02 11:21 Sedat Dilek wrote:
> On Sat, Apr 2, 2016 at 7:19 PM, Jörg Otte wrote:
>> 2016-04-02 17:28 GMT+02:00 Srinivas Pandruvada wrote:
>>>
>>> If you are using Ubuntu, the OS has a script which will automatically
>>> change from performance.
>>> Doug can give more information on this script.
>
>> maybe:
>> /etc/init.d/ondemand

Yes.

> With CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL=y (linux-pm.git#linux-next) I get...
>
> $ cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver
> acpi-cpufreq
> acpi-cpufreq
> acpi-cpufreq
> acpi-cpufreq
>
> $ cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
> ondemand
> ondemand
> ondemand
> ondemand

Yes, those are the expected results for the acpi-cpufreq CPU frequency scaling driver.
You should be able to observe the governor set to sched util for the first minute
after re-boot and/or if you set it yourself after the /etc/init.d/ondemand script
has finished (i.e. more than 1 minute after re-boot.)

> ...is there a difference when using intel_pstate as scaling_driver?

Yes, but only because there are different available governors for the two drivers.

> Are the scripts of Ubuntu working properly with acpi-cpufreq (only)?

As far as I know the /etc/init.d/ondemand is working properly. It sets the acpi-cpufreq
driver to use the "ondemand" governor and it sets the intel_pstate driver to use the
"powersave" governor.

... Doug