linux-kernel - Re: [PATCH 09/19] sched/fair: Count tasks prefering each LLC in a sched group

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Message-ID: <aa850892-b172-449d-ae81-d974bb7f4a96@amd.com>
Date: Mon, 27 Oct 2025 14:03:02 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Tim Chen <tim.c.chen@...ux.intel.com>, Peter Zijlstra
	<peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, "Gautham R . Shenoy"
	<gautham.shenoy@....com>
CC: Vincent Guittot <vincent.guittot@...aro.org>, Juri Lelli
	<juri.lelli@...hat.com>, Dietmar Eggemann <dietmar.eggemann@....com>, "Steven
 Rostedt" <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman
	<mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>, "Madadi Vineeth
 Reddy" <vineethr@...ux.ibm.com>, Hillf Danton <hdanton@...a.com>, "Shrikanth
 Hegde" <sshegde@...ux.ibm.com>, Jianyong Wu <jianyong.wu@...look.com>, Yangyu
 Chen <cyy@...self.name>, Tingyin Duan <tingyin.duan@...il.com>, "Vern Hao"
	<vernhao@...cent.com>, Len Brown <len.brown@...el.com>, Aubrey Li
	<aubrey.li@...el.com>, Zhao Liu <zhao1.liu@...el.com>, Chen Yu
	<yu.chen.surf@...il.com>, Chen Yu <yu.c.chen@...el.com>, Libo Chen
	<libo.chen@...cle.com>, Adam Li <adamli@...amperecomputing.com>, Tim Chen
	<tim.c.chen@...el.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 09/19] sched/fair: Count tasks prefering each LLC in a
 sched group

Hello Tim,

On 10/11/2025 11:54 PM, Tim Chen wrote:
> +#ifdef CONFIG_SCHED_CACHE
> +		if (sched_cache_enabled()) {
> +			int j;
> +
> +			for (j = 0; j < max_llcs; ++j)
> +				sgs->nr_pref_llc[j] += rq->nr_pref_llc[j];
> +		}
> +#endif

If I'm not mistaken, we only compare
"sds->nr_pref_llc[llc_idx(env->dst_cpu)]"
and the destination LLC is always fixes. Do we need to aggregate the
data for all the LLCs? Is a single "nr_pref_llc_dest" enough?

>  		/*
>  		 * No need to call idle_cpu() if nr_running is not 0
>  		 */

-- 
Thanks and Regards,
Prateek