linux-kernel - Re: [PATCH 07/19] sched/fair: Track LLC-preferred tasks per runqueue

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Message-ID: <20251016074434.GZ3289052@noisy.programming.kicks-ass.net>
Date: Thu, 16 Oct 2025 09:44:34 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Tim Chen <tim.c.chen@...ux.intel.com>
Cc: Ingo Molnar <mingo@...hat.com>,
	K Prateek Nayak <kprateek.nayak@....com>,
	"Gautham R . Shenoy" <gautham.shenoy@....com>,
	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 07/19] sched/fair: Track LLC-preferred tasks per runqueue

On Wed, Oct 15, 2025 at 01:03:37PM -0700, Tim Chen wrote:
> On Wed, 2025-10-15 at 14:05 +0200, Peter Zijlstra wrote:
> > On Sat, Oct 11, 2025 at 11:24:44AM -0700, Tim Chen wrote:
> > > @@ -3999,6 +4038,7 @@ account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
> > >  		struct rq *rq = rq_of(cfs_rq);
> > >  
> > >  		account_numa_enqueue(rq, task_of(se));
> > > +		account_llc_enqueue(rq, task_of(se));
> > >  		list_add(&se->group_node, &rq->cfs_tasks);
> > 
> > Here and...
> > 
> > >  	}
> > >  	cfs_rq->nr_queued++;
> > > @@ -4010,9 +4050,14 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
> > >  	update_load_sub(&cfs_rq->load, se->load.weight);
> > >  	if (entity_is_task(se)) {
> > >  		account_numa_dequeue(rq_of(cfs_rq), task_of(se));
> > > +		account_llc_dequeue(rq_of(cfs_rq), task_of(se));
> > 
> > ... here, could you please check the compiler is doing CSE of task_of()?
> 
> Will consolidate those task_of(se). 

And rq_of(). But really, check code-gen, it *should* DTRT and CSE the
lot. If it doesn't, then do it manually.