Re: [PATCH v10 02/12] Documentation: amd-pstate: add EPP profiles introduction

Huang Rui
2023-01-17T11:46:01Z

On Fri, Jan 06, 2023 at 02:14:10PM +0800, Yuan, Perry 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_preferences
> 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"
>
> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>

Acked-by: Huang Rui <ray.huang@amd.com>

> ---
> 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`.
>
> --
> 2.34.1
>