linux-kernel - Re: [PATCH v8 5/6] Documentation: cpufreq: amd-pstate: introduce the new cpu boost control method

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Date: Fri, 26 Apr 2024 09:10:24 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.com,
 viresh.kumar@...aro.org, Ray.Huang@....com, gautham.shenoy@....com,
 Borislav.Petkov@....com
Cc: Alexander.Deucher@....com, Xinmei.Huang@....com, Xiaojian.Du@....com,
 Li.Meng@....com, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 5/6] Documentation: cpufreq: amd-pstate: introduce the
 new cpu boost control method

On 4/26/2024 01:34, Perry Yuan wrote:
> From: Perry Yuan <Perry.Yuan@....com>
> 
> Introduce AMD CPU frequency boosting control sysfs entry which used for
> switching boost on and boost off.
> 
> If core performance boost is disabled while a core is in a boosted P-state,
> the core automatically transitions to the highest performance non-boosted P-state
> The highest perf and frequency will be limited by the setting value.
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> ---
>   Documentation/admin-guide/pm/amd-pstate.rst | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index 1e0d101b020a..82fbd01da658 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -440,6 +440,17 @@ control its functionality at the system level.  They are located in the
>           This attribute is read-only to check the state of preferred core set
>           by the kernel parameter.
>   
> +``cpb_boost``
> +        Specifies whether core performance boost is requested to be enabled or disabled
> +        If core performance boost is disabled while a core is in a boosted P-state, the
> +        core automatically transitions to the highest performance non-boosted P-state.
> +        AMD Core Performance Boost(CPB) is controlled by this new attribute file which

The attribute is currently new, but by the time this is merged it will 
be old.  Avoid using "new" or "old" in documentation.

> +        allow user to change all cores frequency boosting state. It supports both
> +        ``active``, ``passive`` and ``guided`` mode control with below value write to it.

How about just say "supports all amd-pstate modes"?

> +
> +        "0" Disable Core Performance Boosting
> +        "1" Enable  Core Performance Boosting
> +
>   ``cpupower`` tool support for ``amd-pstate``
>   ===============================================
>