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Date: Thu, 19 Feb 2026 17:50:09 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
	"Gautham R . Shenoy" <gautham.shenoy@amd.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Chen Yu <yu.c.chen@intel.com>, Juri Lelli <juri.lelli@redhat.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>,
	Madadi Vineeth Reddy <vineethr@linux.ibm.com>,
	Hillf Danton <hdanton@sina.com>,
	Shrikanth Hegde <sshegde@linux.ibm.com>,
	Jianyong Wu <jianyong.wu@outlook.com>,
	Yangyu Chen <cyy@cyyself.name>,
	Tingyin Duan <tingyin.duan@gmail.com>,
	Vern Hao <vernhao@tencent.com>, Vern Hao <haoxing990@gmail.com>,
	Len Brown <len.brown@intel.com>, Aubrey Li <aubrey.li@intel.com>,
	Zhao Liu <zhao1.liu@intel.com>, Chen Yu <yu.chen.surf@gmail.com>,
	Adam Li <adamli@os.amperecomputing.com>,
	Aaron Lu <ziqianlu@bytedance.com>, Tim Chen <tim.c.chen@intel.com>,
	Josh Don <joshdon@google.com>, Gavin Guo <gavinguo@igalia.com>,
	Qais Yousef <qyousef@layalina.io>,
	Libo Chen <libchen@purestorage.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 15/21] sched/cache: Disable cache aware scheduling for
 processes with high thread counts
Message-ID: <20260219165009.GL1395266@noisy.programming.kicks-ass.net>
References: <cover.1770760558.git.tim.c.chen@linux.intel.com>
 <f3113a94a9494371517c912e3dae4e1ca0cb195f.1770760558.git.tim.c.chen@linux.intel.com>
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In-Reply-To: <f3113a94a9494371517c912e3dae4e1ca0cb195f.1770760558.git.tim.c.chen@linux.intel.com>

On Tue, Feb 10, 2026 at 02:18:55PM -0800, Tim Chen wrote:

> +static bool exceed_llc_nr(struct mm_struct *mm, int cpu)
> +{
> +	int smt_nr = 1;
> +
> +#ifdef CONFIG_SCHED_SMT
> +	if (sched_smt_active())
> +		smt_nr = cpumask_weight(cpu_smt_mask(cpu));

cpu_smt_num_threads ?

> +#endif
> +
> +	return !fits_capacity((mm->sc_stat.nr_running_avg * smt_nr),
> +			per_cpu(sd_llc_size, cpu));
> +}