RE: [PATCH v9 02/13] Documentation: amd-pstate: add EPP profiles introduction

Yuan, Perry
2023-01-05T03:19:06Z

[AMD Official Use Only - General]

Hi Mario.

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@amd.com>
> Sent: Wednesday, January 4, 2023 8:29 AM
> To: Yuan, Perry <Perry.Yuan@amd.com>; rafael.j.wysocki@intel.com; Huang,
> Ray <Ray.Huang@amd.com>; viresh.kumar@linaro.org
> Cc: Sharma, Deepak <Deepak.Sharma@amd.com>; Fontenot, Nathan
> <Nathan.Fontenot@amd.com>; Deucher, Alexander
> <Alexander.Deucher@amd.com>; Huang, Shimmer
> <Shimmer.Huang@amd.com>; Du, Xiaojian <Xiaojian.Du@amd.com>; Meng,
> Li (Jassmine) <Li.Meng@amd.com>; Karny, Wyes <Wyes.Karny@amd.com>;
> linux-pm@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v9 02/13] Documentation: amd-pstate: add EPP profiles
> introduction
>
> On 12/25/2022 10:34, Perry Yuan wrote:
> > From: Perry Yuan <Perry.Yuan@amd.com>
> >
> > The amd-pstate driver supports a feature called energy performance
> > preference (EPP). Add information to the documentation to explain how
> > users can interact with the sysfs files for this feature.
> >
> > 1) See all EPP profiles
> > $ sudo cat
> >
> /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_available_pr
> ef
> > erences default performance balance_performance balance_power power
> >
> > 2) Check current EPP profile
> > $ sudo cat
> > /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference
> > performance
> >
> > 3) Set new EPP profile
> > $ sudo bash -c "echo power >
> /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference"
> >
> > Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
>
> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
>

I just got back from sick leave, will pick all your R-B flags and send v10 out.
Thank you help to review this version.

Perry.

> > ---
> > Documentation/admin-guide/pm/amd-pstate.rst | 19
> +++++++++++++++++++
> > 1 file changed, 19 insertions(+)
> >
> > diff --git a/Documentation/admin-guide/pm/amd-pstate.rst
> > b/Documentation/admin-guide/pm/amd-pstate.rst
> > index 06e23538f79c..33ab8ec8fc2f 100644
> > --- a/Documentation/admin-guide/pm/amd-pstate.rst
> > +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> > @@ -262,6 +262,25 @@ lowest non-linear performance in `AMD CPPC
> Performance Capability
> > <perf_cap_>`_.)
> > This attribute is read-only.
> >
> > +``energy_performance_available_preferences``
> > +
> > +A list of all the supported EPP preferences that could be used for
> > +``energy_performance_preference`` on this system.
> > +These profiles represent different hints that are provided to the
> > +low-level firmware about the user's desired energy vs efficiency
> > +tradeoff. ``default`` represents the epp value is set by platform
> > +firmware. This attribute is read-only.
> > +
> > +``energy_performance_preference``
> > +
> > +The current energy performance preference can be read from this
> attribute.
> > +and user can change current preference according to energy or
> > +performance needs Please get all support profiles list from
> > +``energy_performance_available_preferences`` attribute, all the
> > +profiles are integer values defined between 0 to 255 when EPP feature
> > +is enabled by platform firmware, if EPP feature is disabled, driver
> > +will ignore the written value This attribute is read-write.
> > +
> > Other performance and frequency values can be read back from
> > ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.
> >