On Mon, Apr 27, 2020 at 10:37:05AM +0200, Dietmar Eggemann wrote:
> Return the weight of the rd (root domain) span in case it is a subset
> of the cpu_active_mask.
>
> Continue to compute the number of CPUs over rd span and cpu_active_mask
> when in hotplug.
>
> Signed-off-by: Dietmar Eggemann <dietmar.eggem...@arm.com>
> ---
> kernel/sched/deadline.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index 504d2f51b0d6..4ae22bfc37ae 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -54,10 +54,16 @@ static inline struct dl_bw *dl_bw_of(int i)
> static inline int dl_bw_cpus(int i)
> {
> struct root_domain *rd = cpu_rq(i)->rd;
> - int cpus = 0;
> + int cpus;
>
> RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
> "sched RCU must be held");
> +
> + if (cpumask_subset(rd->span, cpu_active_mask))
> + return cpumask_weight(rd->span);
> +
Looks good to me. This is a nice optimization.
> + cpus = 0;
> +
> for_each_cpu_and(i, rd->span, cpu_active_mask)
> cpus++;
>
Do you know why this check is in place? Is it only to cover
the case of cpuset_cpu_inactive()->dl_cpu_busy()?
Thanks,
Pavan
> --
> 2.17.1
>
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