linux-kernel - Re: [PATCH] sched/deadline: simplify dl_bw_cpus() using cpumask_weight

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Message-ID: <5e5c9d89-0751-abc2-4d43-5c8083735724@arm.com>
Date:   Mon, 22 May 2023 18:58:20 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Miaohe Lin <linmiaohe@...wei.com>, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org
Cc:     rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched/deadline: simplify dl_bw_cpus() using
 cpumask_weight_and()

On 22/05/2023 13:56, Miaohe Lin wrote:
> cpumask_weight_and() can be used to count of bits both in rd->span and
> cpu_active_mask. No functional change intended.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> ---
>  kernel/sched/deadline.c | 11 +----------
>  1 file changed, 1 insertion(+), 10 deletions(-)
> 
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index 166c3e6eae61..fe983ed7bb12 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -110,20 +110,11 @@ 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;
>  
>  	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);
> -
> -	cpus = 0;
> -
> -	for_each_cpu_and(i, rd->span, cpu_active_mask)
> -		cpus++;
> -
> -	return cpus;
> +	return cpumask_weight_and(rd->span, cpu_active_mask);
>  }
>  
>  static inline unsigned long __dl_bw_capacity(const struct cpumask *mask)

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@....com>