Re: [PATCH] sched/pelt: Fix truncation of the PELT period count

[Kayra Cizmeci <kayracizmeci@gmail.com>]

On Thu, Oct 22, 2026 at 12:49:30PM +0900, Hui Su wrote:
> accumulate_sum() computes the number of elapsed PELT periods in a
> u64 but returns u32. When the count is a multiple of 2^32, it is
> truncated to zero even though the PELT sums have been updated.
> 
> The caller interprets zero as no period boundary crossed and skips
> recomputing the averages, leaving *_avg stale relative to *_sum.
> 
> Return only whether any period elapsed, which is all the caller
> needs.
> 
> Signed-off-by: Hui Su <sh_def@163.com>
> ---
>  kernel/sched/pelt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
> index 779eb58a4261..519bc9c40043 100644
> --- a/kernel/sched/pelt.c
> +++ b/kernel/sched/pelt.c
> @@ -146,7 +146,7 @@ accumulate_sum(u64 delta, struct sched_avg *sa,
>  	if (running)
>  		sa->util_sum += contrib << SCHED_CAPACITY_SHIFT;
>  
> -	return periods;
> +	return !!periods;
>  }

I think making this return value u64 is cleaner (As Prateek says).
Both works for me tho. 

Reviewed-by: Kayra Cizmeci <kayracizmeci@gmail.com>

>  
>  /*
> -- 
> 2.55.0
>