Re: [PATCH] sched/fair: use cpumask_weight_and() in sched_balance_find_dst_group()

[K Prateek Nayak <kprateek.nayak@amd.com>]

Hello Yury,

On 9/11/2025 9:14 AM, Yury Norov wrote:
> From: Yury Norov (NVIDIA) <yury.norov@gmail.com>
> 
> In the group_has_spare case, the function creates a temporary cpumask
> to just calculate weight of (p->cpus_ptr & sched_group_span(local)).
> 
> We've got a dedicated helper for it.

Neat! I didn't realize this existed back when I added that cpumask_and()
+ cpumask_weight() combo. Please feel free to include:

Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>

> 
> Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
> ---
>  kernel/sched/fair.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 7229339cbb1b..4ec012912cd1 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -10821,10 +10821,9 @@ sched_balance_find_dst_group(struct sched_domain *sd, struct task_struct *p, int
>  			 * take care of it.
>  			 */
>  			if (p->nr_cpus_allowed != NR_CPUS) {
> -				struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
> -
> -				cpumask_and(cpus, sched_group_span(local), p->cpus_ptr);
> -				imb_numa_nr = min(cpumask_weight(cpus), sd->imb_numa_nr);
> +				unsigned w = cpumask_weight_and(p->cpus_ptr,
> +								sched_group_span(local));
> +				imb_numa_nr = min(w, sd->imb_numa_nr);
>  			}
>  
>  			imbalance = abs(local_sgs.idle_cpus - idlest_sgs.idle_cpus);

-- 
Thanks and Regards,
Prateek