* Re: [PATCH] sched/fair: use cpumask_weight_and() in sched_balance_find_dst_group()
2025-09-11 3:44 [PATCH] sched/fair: use cpumask_weight_and() in sched_balance_find_dst_group() Yury Norov
@ 2025-09-11 6:52 ` K Prateek Nayak
2025-09-11 8:50 ` Vincent Guittot
2025-09-11 8:58 ` Fernand Sieber
2 siblings, 0 replies; 4+ messages in thread
From: K Prateek Nayak @ 2025-09-11 6:52 UTC (permalink / raw)
To: Yury Norov, Ingo Molnar, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, linux-kernel
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
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] sched/fair: use cpumask_weight_and() in sched_balance_find_dst_group()
2025-09-11 3:44 [PATCH] sched/fair: use cpumask_weight_and() in sched_balance_find_dst_group() Yury Norov
2025-09-11 6:52 ` K Prateek Nayak
@ 2025-09-11 8:50 ` Vincent Guittot
2025-09-11 8:58 ` Fernand Sieber
2 siblings, 0 replies; 4+ messages in thread
From: Vincent Guittot @ 2025-09-11 8:50 UTC (permalink / raw)
To: Yury Norov
Cc: Ingo Molnar, Peter Zijlstra, Juri Lelli, Dietmar Eggemann,
Steven Rostedt, Ben Segall, Mel Gorman, Valentin Schneider,
linux-kernel
On Thu, 11 Sept 2025 at 05:44, Yury Norov <yury.norov@gmail.com> 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.
>
> Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
> ---
> 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);
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] sched/fair: use cpumask_weight_and() in sched_balance_find_dst_group()
2025-09-11 3:44 [PATCH] sched/fair: use cpumask_weight_and() in sched_balance_find_dst_group() Yury Norov
2025-09-11 6:52 ` K Prateek Nayak
2025-09-11 8:50 ` Vincent Guittot
@ 2025-09-11 8:58 ` Fernand Sieber
2 siblings, 0 replies; 4+ messages in thread
From: Fernand Sieber @ 2025-09-11 8:58 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot,
Dietmar Eggemann, Steven Rostedt, Ben Segall, Mel Gorman,
Valentin Schneider, linux-kernel, Yury Norov
On Wed, 10 Sep 2025 23:44:52 -0400, Yury Norov wrote:
> 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.
>
>
LGTM
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
--
Thanks,
Fernand
Amazon Development Centre (South Africa) (Proprietary) Limited
29 Gogosoa Street, Observatory, Cape Town, Western Cape, 7925, South Africa
Registration Number: 2004 / 034463 / 07
^ permalink raw reply [flat|nested] 4+ messages in thread