Re: [PATCH] thermal: gov_power_allocator: Fix incorrect calculation in divvy_up_power

[Lukasz Luba]

On 2/20/25 19:45, Rafael J. Wysocki wrote:
> On Wed, Feb 19, 2025 at 8:07 AM Yu-Che Cheng <giver@xxxxxxxxxxxx> wrote:
> > divvy_up_power should use weighted_req_power instead of req_power to
> > calculate the granted_power. Otherwise, the granted_power may be
> > unexpected as the denominator total_req_power is weighted sum.
>
> Yes, this is what's happening, to my eyes.
>
> > This is a mistake during the previous refactor.
> >
> > Replace the req_power with weighted_req_power in divvy_up_power
> > calculation.
> >
> > Fixes: 912e97c67cc3 ("thermal: gov_power_allocator: Move memory allocation out of throttle()")
> > Signed-off-by: Yu-Che Cheng <giver@xxxxxxxxxxxx>
> > ---
> >   drivers/thermal/gov_power_allocator.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
> > index 3b644de3292e..3b626db55b2b 100644
> > --- a/drivers/thermal/gov_power_allocator.c
> > +++ b/drivers/thermal/gov_power_allocator.c
> > @@ -370,7 +370,7 @@ static void divvy_up_power(struct power_actor *power, int num_actors,
> >
> >          for (i = 0; i < num_actors; i++) {
> >                  struct power_actor *pa = &power[i];
> > -               u64 req_range = (u64)pa->req_power * power_range;
> > +               u64 req_range = (u64)pa->weighted_req_power * power_range;
> >
> >                  pa->granted_power = DIV_ROUND_CLOSEST_ULL(req_range,
> >                                                            total_req_power);
> >
> > ---
>
> And the fix looks good to me.
>
> Lukasz, any concerns?

Good catch! It went through since the test didn't set different weights.

Thanks for the fix!

Reviewed-by: Lukasz Luba <lukasz.luba@xxxxxxx>