linux-kernel - [PATCH v3 1/8] sched/topology: Compute sd

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Message-ID: <20260120113246.27987-2-kprateek.nayak@amd.com>
Date: Tue, 20 Jan 2026 11:32:39 +0000
From: K Prateek Nayak <kprateek.nayak@....com>
To: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot
	<vincent.guittot@...aro.org>, <linux-kernel@...r.kernel.org>
CC: 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>, Chen Yu
	<yu.c.chen@...el.com>, Shrikanth Hegde <sshegde@...ux.ibm.com>, "Gautham R.
 Shenoy" <gautham.shenoy@....com>, K Prateek Nayak <kprateek.nayak@....com>
Subject: [PATCH v3 1/8] sched/topology: Compute sd_weight considering cpuset partitions

The "sd_weight" used for calculating the load balancing interval, and
its limits, considers the span weight of the entire topology level
without accounting for cpuset partitions.

Compute the "sd_weight" after computing the "sd_span" considering the
cpu_map covered by the partition, and set the load balancing interval,
and its limits accordingly.

Fixes: cb83b629bae03 ("sched/numa: Rewrite the CONFIG_NUMA sched domain support")
Signed-off-by: K Prateek Nayak <kprateek.nayak@....com>
---
Changelog rfc v2..v3:

o New patch.
---
 kernel/sched/topology.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index cf643a5ddedd..649674bb6c3c 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1638,8 +1638,6 @@ sd_init(struct sched_domain_topology_level *tl,
 	int sd_id, sd_weight, sd_flags = 0;
 	struct cpumask *sd_span;
 
-	sd_weight = cpumask_weight(tl->mask(tl, cpu));
-
 	if (tl->sd_flags)
 		sd_flags = (*tl->sd_flags)();
 	if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
@@ -1647,8 +1645,6 @@ sd_init(struct sched_domain_topology_level *tl,
 		sd_flags &= TOPOLOGY_SD_FLAGS;
 
 	*sd = (struct sched_domain){
-		.min_interval		= sd_weight,
-		.max_interval		= 2*sd_weight,
 		.busy_factor		= 16,
 		.imbalance_pct		= 117,
 
@@ -1668,7 +1664,6 @@ sd_init(struct sched_domain_topology_level *tl,
 					,
 
 		.last_balance		= jiffies,
-		.balance_interval	= sd_weight,
 
 		/* 50% success rate */
 		.newidle_call		= 512,
@@ -1685,6 +1680,11 @@ sd_init(struct sched_domain_topology_level *tl,
 	cpumask_and(sd_span, cpu_map, tl->mask(tl, cpu));
 	sd_id = cpumask_first(sd_span);
 
+	sd_weight = cpumask_weight(sd_span);
+	sd->min_interval = sd_weight;
+	sd->max_interval = 2 * sd_weight;
+	sd->balance_interval = sd_weight;
+
 	sd->flags |= asym_cpu_capacity_classify(sd_span, cpu_map);
 
 	WARN_ONCE((sd->flags & (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY)) ==
-- 
2.34.1