linux-kernel - Re: [PATCH] sched/fair: Force idle aware load balancing

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Message-ID: <20251128111427.GJ3245006@noisy.programming.kicks-ass.net>
Date: Fri, 28 Nov 2025 12:14:27 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Fernand Sieber <sieberf@...zon.com>
Cc: mingo@...hat.com, linux-kernel@...r.kernel.org, juri.lelli@...hat.com,
	vincent.guittot@...aro.org, dietmar.eggemann@....com,
	rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
	vschneid@...hat.com, kprateek.nayak@....com, dwmw@...zon.co.uk,
	jschoenh@...zon.de, liuyuxua@...zon.com, abusse@...zon.com,
	gmazz@...zon.com, rkagan@...zon.com
Subject: Re: [PATCH] sched/fair: Force idle aware load balancing

On Thu, Nov 27, 2025 at 10:27:17PM +0200, Fernand Sieber wrote:

> @@ -11123,7 +11136,8 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
>  		return;
>  	}
>  
> -	if (busiest->group_type == group_smt_balance) {
> +	if (busiest->group_type == group_smt_balance ||
> +	    busiest->forceidle_weight) {

Should we not instead make it so that we select group_smt_balance in
this case?

Anyway, the patch doesn't seem horrible to me. Vincent?

>  		/* Reduce number of tasks sharing CPU capacity */
>  		env->migration_type = migrate_task;
>  		env->imbalance = 1;