Re: [RFC PATCH v5] sched/fair: select idle cpu from idle cpumask for task wakeup

[Peter Zijlstra]

On Wed, Nov 18, 2020 at 12:31:13PM +0800, Aubrey Li wrote:
> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
> index f324dc36fc43..6f5947673e66 100644
> --- a/kernel/sched/idle.c
> +++ b/kernel/sched/idle.c
> @@ -163,6 +163,7 @@ static void cpuidle_idle_call(void)
>  	 */
>  
>  	if (cpuidle_not_available(drv, dev)) {
> +		update_idle_cpumask(this_rq(), true);
>  		tick_nohz_idle_stop_tick();
>  
>  		default_idle_call();
> @@ -193,6 +194,7 @@ static void cpuidle_idle_call(void)
>  			max_latency_ns = dev->forced_idle_latency_limit_ns;
>  		}
>  
> +		update_idle_cpumask(this_rq(), true);
>  		tick_nohz_idle_stop_tick();
>  
>  		next_state = cpuidle_find_deepest_state(drv, dev, max_latency_ns);
> @@ -205,10 +207,12 @@ static void cpuidle_idle_call(void)
>  		 */
>  		next_state = cpuidle_select(drv, dev, &stop_tick);
>  
> -		if (stop_tick || tick_nohz_tick_stopped())
> +		if (stop_tick || tick_nohz_tick_stopped()) {
> +			update_idle_cpumask(this_rq(), true);
>  			tick_nohz_idle_stop_tick();

We already have a callback in tick_nohz_idle_stop_tick(), namely
nohz_balance_enter_idle().