Re: [PATCH] sched/topology: optimize sched_numa_find_nth_cpu()

[Valentin Schneider]

On 19/03/26 13:26, Yury Norov wrote:
> The binary search callback hop_cmp() uses cpumask_weight_and() on each
> iteration. Switch it to cpumask_nth_and() as it returns earlier, as
> soon as the required number of CPUs is found.
>
> Signed-off-by: Yury Norov <ynorov@xxxxxxxxxx>



> ---
>  kernel/sched/topology.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index 32dcddaead82..0437f5ded37b 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -2267,7 +2267,7 @@ static int hop_cmp(const void *a, const void *b)
>  	struct cpumask **prev_hop, **cur_hop = *(struct cpumask ***)b;
>  	struct __cmp_key *k = (struct __cmp_key *)a;
>  
> -	if (cpumask_weight_and(k->cpus, cur_hop[k->node]) <= k->cpu)
> +	if (cpumask_nth_and(k->cpu, k->cpus, cur_hop[k->node]) >= nr_cpu_ids)
>  		return 1;
>  
>  	if (b == k->masks) {
> -- 
> 2.43.0