Re: [PATCH] sched/topology: Balance cluster static-key updates

[K Prateek Nayak <kprateek.nayak@amd.com>]

Hello Hui,

On 10/21/2026 9:13 AM, Hui Su wrote:
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index 3dab0253976fb..c9e10bfade6d0 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -3314,12 +3314,22 @@ int __init sched_init_domains(const struct cpumask *cpu_map)
>  static void detach_destroy_domains(const struct cpumask *cpu_map)
>  {
>  	unsigned int cpu = cpumask_any(cpu_map);
> +	bool has_cluster = false;
>  	int i;
>  
>  	if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu)))
>  		static_branch_dec_cpuslocked(&sched_asym_cpucapacity);
>  
> -	if (static_branch_unlikely(&sched_cluster_active))
> +	rcu_read_lock();
> +	for_each_cpu(i, cpu_map) {
> +		if (lowest_flag_domain(i, SD_CLUSTER)) {
> +			has_cluster = true;
> +			break;
> +		}
> +	}
> +	rcu_read_unlock();

nit.

This should be done only when sched_cluster_active is enabled to
avoid the extra loop on systems that don't have any cluster domain.

Apart from that, feel free to include:

Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>

> +
> +	if (has_cluster)
>  		static_branch_dec_cpuslocked(&sched_cluster_active);
>  
>  	rcu_read_lock();

-- 
Thanks and Regards,
Prateek