linux-kernel - Re: [PATCH 2/3] sched/fair: Ignore isolated cpus in update_numa

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Message-ID: <92168453-ecf0-4849-970d-4c19a5a610dc@amd.com>
Date: Wed, 18 Dec 2024 11:56:19 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Chuyi Zhou <zhouchuyi@...edance.com>, <mingo@...hat.com>,
	<peterz@...radead.org>, <juri.lelli@...hat.com>,
	<vincent.guittot@...aro.org>, <dietmar.eggemann@....com>,
	<rostedt@...dmis.org>, <bsegall@...gle.com>, <mgorman@...e.de>,
	<vschneid@...hat.com>
CC: <chengming.zhou@...ux.dev>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] sched/fair: Ignore isolated cpus in update_numa_stat

Hello Chuyi,

On 12/16/2024 5:53 PM, Chuyi Zhou wrote:
> [..snip..] 
> @@ -2125,6 +2125,11 @@ static void update_numa_stats(struct task_numa_env *env,
>   	for_each_cpu(cpu, cpumask_of_node(nid)) {

Looking at sched_init_domains(), we only build sched domains only for
active CPUs in housekeeping_cpumask(HK_TYPE_DOMAIN) so similar to the
question on Patch 3, can we get away with just modifying this outer loop
to:

	for_each_cpu_and(cpu, cpumask_of_node(nid), housekeeping_cpumask(HK_TYPE_DOMAIN)) {
		...
	}

Thoughts?

-- 
Thanks and Regards,
Prateek

>   		struct rq *rq = cpu_rq(cpu);
>   
> +		/* skip isolated cpus' load */
> +		if (!rcu_dereference(rq->sd))
> +			continue;
> +
> +		ns->weight++;
>   		ns->load += cpu_load(rq);
>   		ns->runnable += cpu_runnable(rq);
>   		ns->util += cpu_util_cfs(cpu);
> @@ -2144,8 +2149,6 @@ static void update_numa_stats(struct task_numa_env *env,
>   	}
>   	rcu_read_unlock();
>   
> -	ns->weight = cpumask_weight(cpumask_of_node(nid));
> -
>   	ns->node_type = numa_classify(env->imbalance_pct, ns);
>   
>   	if (idle_core >= 0)