*powersave* governor shown despite disabled in configuration

*powersave* governor shown despite disabled in configuration

[Paul Menzel]

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Dear Linux folks,


With Linux 4.14.76, the scaling governor *powersave* is shown as
being available despite being disabled in the configuration.

```
$ uname -a
Linux xxx.molgen.mpg.de 4.14.76.mx64.228 #1 SMP Tue Oct 16 19:20:58 CEST 2018 x86_64 GNU/Linux
$ zcat /proc/config.gz |grep CONFIG_CPU_FREQ
CONFIG_CPU_FREQ=y
# CONFIG_CPU_FREQ_STAT is not set
CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y
# CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE is not set
# CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE is not set
# CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND is not set
# CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE is not set
# CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL is not set
CONFIG_CPU_FREQ_GOV_PERFORMANCE=y
# CONFIG_CPU_FREQ_GOV_POWERSAVE is not set
# CONFIG_CPU_FREQ_GOV_USERSPACE is not set
# CONFIG_CPU_FREQ_GOV_ONDEMAND is not set
# CONFIG_CPU_FREQ_GOV_CONSERVATIVE is not set
# CONFIG_CPU_FREQ_GOV_SCHEDUTIL is not set
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors 
performance powersave
$ cat  /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
performance
```


Kind regards,

Paul


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Re: *powersave* governor shown despite disabled in configuration

[Dominik Brodowski]

On Mon, Dec 10, 2018 at 04:30:05PM +0100, Paul Menzel wrote:
> Dear Linux folks,
> 
> 
> With Linux 4.14.76, the scaling governor *powersave* is shown as
> being available despite being disabled in the configuration.

Which cpufreq driver do you use? Presumably intel_pstate? That driver
exposes internal policies / "governors" named "performance" and "powersave",
which are unrelated to CONFIG_CPU_FREQ_GOV_POWERSAVE.

Thanks,
	Dominik

Re: [solved] *powersave* governor shown despite disabled in configuration

[Paul Menzel]

Dear Dominik,


Thank you for your quick response.


Am 11.12.18 um 07:51 schrieb Dominik Brodowski:
> On Mon, Dec 10, 2018 at 04:30:05PM +0100, Paul Menzel wrote:

>> With Linux 4.14.76, the scaling governor *powersave* is shown as
>> being available despite being disabled in the configuration.
> 
> Which cpufreq driver do you use? Presumably intel_pstate?

Yes, intel_pstate.

> That driver exposes internal policies / "governors" named 
> "performance" and "powersave", which are unrelated to
> CONFIG_CPU_FREQ_GOV_POWERSAVE.
Indeed, that confused me, and I didn’t read the documentation
carefully enough.

> They are not generic scaling governors, but their names are the same as the
> names of some of those governors.  Moreover, confusingly enough, they generally
> do not work in the same way as the generic governors they share the names with.
> For example, the ``powersave`` P-state selection algorithm provided by
> ``intel_pstate`` is not a counterpart of the generic ``powersave`` governor
> (roughly, it corresponds to the ``schedutil`` and ``ondemand`` governors).
> 
> There are two P-state selection algorithms provided by ``intel_pstate`` in the
> active mode: ``powersave`` and ``performance``.  The way they both operate
> depends on whether or not the hardware-managed P-states (HWP) feature has been
> enabled in the processor and possibly on the processor model.


Kind regards,

Paul


[1]: https://www.kernel.org/doc/html/latest/admin-guide/pm/intel_pstate.html