Re: [PATCH 48/54] kernel/time: replace cpumask_weight with cpumask_weight_eq where appropriate

[Peter Zijlstra]

On Sun, Jan 23, 2022 at 10:39:19AM -0800, Yury Norov wrote:
> tick_cleanup_dead_cpu() calls cpumask_weight() to compare the weight
> of cpumask with a given number. We can do it more efficiently with
> cpumask_weight_eq() because conditional cpumask_weight may stop
> traversing the cpumask earlier, as soon as condition is met.

But again, nobody gives a crap about performance here..

> Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
> ---
>  kernel/time/clockevents.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
> index 003ccf338d20..32d6629a55b2 100644
> --- a/kernel/time/clockevents.c
> +++ b/kernel/time/clockevents.c
> @@ -648,7 +648,7 @@ void tick_cleanup_dead_cpu(int cpu)
>  	 */
>  	list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
>  		if (cpumask_test_cpu(cpu, dev->cpumask) &&
> -		    cpumask_weight(dev->cpumask) == 1 &&
> +		    cpumask_weight_eq(dev->cpumask, 1) &&
>  		    !tick_is_broadcast_device(dev)) {
>  			BUG_ON(!clockevent_state_detached(dev));
>  			list_del(&dev->list);
> -- 
> 2.30.2
>