linux-kernel - [tip: sched/core] sched/fair: Use cpumask_weight_and() in sched_balance_find_dst

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Message-ID: <176820500577.510.10215655917802186780.tip-bot2@tip-bot2>
Date: Mon, 12 Jan 2026 08:03:25 -0000
From: "tip-bot2 for Yury Norov (NVIDIA)" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Yury Norov (NVIDIA)" <yury.norov@...il.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Vincent Guittot <vincent.guittot@...aro.org>,
 K Prateek Nayak <kprateek.nayak@....com>, Fernand Sieber <sieberf@...zon.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/fair: Use cpumask_weight_and() in
 sched_balance_find_dst_group()

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     55b39b0cf183b9c682717a55a2fba06da69bba6b
Gitweb:        https://git.kernel.org/tip/55b39b0cf183b9c682717a55a2fba06da69bba6b
Author:        Yury Norov (NVIDIA) <yury.norov@...il.com>
AuthorDate:    Sat, 06 Dec 2025 22:42:47 -05:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 08 Jan 2026 12:43:56 +01:00

sched/fair: Use cpumask_weight_and() in sched_balance_find_dst_group()

In the group_has_spare case, the function creates a temporary cpumask
to just calculate weight of (p->cpus_ptr & sched_group_span(local)).

We've got a dedicated helper for it.

Signed-off-by: Yury Norov (NVIDIA) <yury.norov@...il.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@....com>
Reviewed-by: Fernand Sieber <sieberf@...zon.com>
Link: https://patch.msgid.link/20251207034247.402926-1-yury.norov@gmail.com
---
 kernel/sched/fair.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 842a0f2..ebee20f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10974,10 +10974,9 @@ sched_balance_find_dst_group(struct sched_domain *sd, struct task_struct *p, int
 			 * take care of it.
 			 */
 			if (p->nr_cpus_allowed != NR_CPUS) {
-				struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
-
-				cpumask_and(cpus, sched_group_span(local), p->cpus_ptr);
-				imb_numa_nr = min(cpumask_weight(cpus), sd->imb_numa_nr);
+				unsigned int w = cpumask_weight_and(p->cpus_ptr,
+								sched_group_span(local));
+				imb_numa_nr = min(w, sd->imb_numa_nr);
 			}
 
 			imbalance = abs(local_sgs.idle_cpus - idlest_sgs.idle_cpus);