linux-kernel - Re: [PATCH 1/2] PM: EM: Fix incorrect description of the cost field in struct em_perf

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Message-ID: <CAJZ5v0jJqMcG43S_rmFC6S3DRM9+x9m8wx7YdEkuUWGpohBw_g@mail.gmail.com>
Date: Thu, 8 Jan 2026 16:53:51 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Lukasz Luba <lukasz.luba@....com>, Yaxiong Tian <tianyaxiong@...inos.cn>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] PM: EM: Fix incorrect description of the cost field
 in struct em_perf_state

On Tue, Dec 30, 2025 at 10:36 AM Lukasz Luba <lukasz.luba@....com> wrote:
>
>
>
> On 12/30/25 06:15, Yaxiong Tian wrote:
> > Due to commit 1b600da51073 ("PM: EM: Optimize em_cpu_energy() and remove
> > division"), the logic for energy consumption calculation has been modified.
> > The actual calculation of cost is 10 * power * max_frequency / frequency
> > instead of power * max_frequency / frequency.
> >
> > Therefore, the comment for cost has been updated to reflect the correct
> > content.
> >
> > Signed-off-by: Yaxiong Tian <tianyaxiong@...inos.cn>
> > ---
> >   include/linux/energy_model.h | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
> > index 43aa6153dc57..e7497f804644 100644
> > --- a/include/linux/energy_model.h
> > +++ b/include/linux/energy_model.h
> > @@ -18,7 +18,7 @@
> >    * @power:  The power consumed at this level (by 1 CPU or by a registered
> >    *          device). It can be a total power: static and dynamic.
> >    * @cost:   The cost coefficient associated with this level, used during
> > - *           energy calculation. Equal to: power * max_frequency / frequency
> > + *           energy calculation. Equal to: 10 * power * max_frequency / frequency
> >    * @flags:  see "em_perf_state flags" description below.
> >    */
> >   struct em_perf_state {
>
> Good catch, thank you!
>
> Reviewed-by: Lukasz Luba <lukasz.luba@....com>

Applied as 6.19-rc material, thanks!