From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E2BC61EDA0E for ; Wed, 10 Dec 2025 12:53:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765371193; cv=none; b=uObCYPBY7xdW9jXtrHUTYQu2+C5pA9VZhLUt3SC/71ruH7gKQ45FYJTKpoGbwjsZ5REIFi9XNQdr/kkdTb4bAh5MYNa0tyrIRHyE/ISjUgm1cBPr9k0RTV5bSlHQmvcGbKvGk4wTpaPQexjBOORY9pVa3Ne4tDfx08FH8qctF+s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765371193; c=relaxed/simple; bh=ifxmopTGr4kGZWjoZ5Kcczw4SjPyeWlSa3e7w6SxTd0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QJJyQS6fI5wuweB0yshFYvEMApLT+wcycSnSWuk6cOlHfZz8LSgj7aq8rE4IAxgtxMf+ZS1WAZvOV96voo9a5vM2mx//0czFNGzO6AsPTp3ICaPdoaYsq+DBkNGq9yaGiEVbSubs6SFhwXVy2SRWl07sUu7EQk0E/GN+4c5CiI8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=dwasG+PH; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="dwasG+PH" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ul5tHdSJq+RGswKuzl4c7bO5KpQf2DKKRBetgy/IYV0=; b=dwasG+PH6UAD9jqRA0gbBmWlis FIUqJSr/72NlfNbkAn53zc0yNcqLqJdXjiE/t62MwWDQKjz2P4KEOz8Oo5Zxi0uwpvgYJJOiqRQAD Nq/j3M6Iuejqa4+iLK8F6zMXDnEUO0EyZks0kggqbnvesoG1AWVj244OH/oAV72JksW3hQ8k2uawH QSqox0WjhsMnA22u183wubQcvNZafOjsg3lbOCZRfnb9u7X1DCaS1UrvzOATOiSwkZ9tcz1jp80jM +/B/WKEOJz+wG223SEb6e3lXYjUUSTDj69vTNy+X4I8A9LTJF6A57MAH8qlejmliVSiXzekBd3Vsd c3JD2kFw==; Received: from 2001-1c00-8d85-5700-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:5700:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vTJgI-0000000CqsH-1w8h; Wed, 10 Dec 2025 12:52:34 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 2B6F4302EC2; Wed, 10 Dec 2025 13:52:33 +0100 (CET) Date: Wed, 10 Dec 2025 13:52:33 +0100 From: Peter Zijlstra To: Tim Chen Cc: Ingo Molnar , K Prateek Nayak , "Gautham R . Shenoy" , Vincent Guittot , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Madadi Vineeth Reddy , Hillf Danton , Shrikanth Hegde , Jianyong Wu , Yangyu Chen , Tingyin Duan , Vern Hao , Vern Hao , Len Brown , Aubrey Li , Zhao Liu , Chen Yu , Chen Yu , Adam Li , Aaron Lu , Tim Chen , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 09/23] sched/cache: Count tasks prefering destination LLC in a sched group Message-ID: <20251210125233.GT3707891@noisy.programming.kicks-ass.net> References: <1eb6a231ec82b37483208983f0cf10eec823ec9d.1764801860.git.tim.c.chen@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1eb6a231ec82b37483208983f0cf10eec823ec9d.1764801860.git.tim.c.chen@linux.intel.com> On Wed, Dec 03, 2025 at 03:07:28PM -0800, Tim Chen wrote: > During LLC load balancing, tabulate the number of tasks on each runqueue > that prefer the LLC contains the env->dst_cpu in a sched group. > > For example, consider a system with 4 LLC sched groups (LLC0 to LLC3) > balancing towards LLC3. LLC0 has 3 tasks preferring LLC3, LLC1 has > 2, and LLC2 has 1. LLC0, having the most tasks preferring LLC3, is > selected as the busiest source to pick tasks from. > > Within a source LLC, the total number of tasks preferring a destination > LLC is computed by summing counts across all CPUs in that LLC. For > instance, if LLC0 has CPU0 with 2 tasks and CPU1 with 1 task preferring > LLC3, the total for LLC0 is 3. > > These statistics allow the load balancer to choose tasks from source > sched groups that best match their preferred LLCs. > > Signed-off-by: Tim Chen > --- > > Notes: > v1->v2: > Convert nr_pref_llc array in sg_lb_stats to a single > variable as only the dst LLC stat is needed. > (K Prateek Nayak) > > kernel/sched/fair.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index b0e87616e377..4d7803f69a74 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -10445,6 +10445,9 @@ struct sg_lb_stats { > unsigned int nr_numa_running; > unsigned int nr_preferred_running; > #endif > +#ifdef CONFIG_SCHED_CACHE > + unsigned int nr_pref_llc; > +#endif At this point I have to note that rq->nr_pref_llc seems like a horrible misnomer, for it being an array, and not an actual number like the naming suggests.