linux-kernel - [PATCH v5 2/3] sched/fair: Change likelyhood of nohz.nr

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Message-ID: <20260115073524.376643-3-sshegde@linux.ibm.com>
Date: Thu, 15 Jan 2026 13:05:23 +0530
From: Shrikanth Hegde <sshegde@...ux.ibm.com>
To: mingo@...nel.org, peterz@...radead.org, vincent.guittot@...aro.org,
        linux-kernel@...r.kernel.org
Cc: sshegde@...ux.ibm.com, kprateek.nayak@....com, juri.lelli@...hat.com,
        vschneid@...hat.com, tglx@...nel.org, dietmar.eggemann@....com,
        anna-maria@...utronix.de, frederic@...nel.org, wangyang.guo@...el.com
Subject: [PATCH v5 2/3] sched/fair: Change likelyhood of nohz.nr_cpus

These days most of the system have multi cores. The likelyhood of
at least one or more CPUs in nohz (idle state) is higher.

Give accurate hint to the branch predictor.

Reviewed-and-tested-by: K Prateek Nayak <kprateek.nayak@....com>
Signed-off-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
---
 kernel/sched/fair.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a4910658c5d6..3d843d1396ec 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12463,9 +12463,9 @@ static void nohz_balancer_kick(struct rq *rq)
 
 	/*
 	 * None are in tickless mode and hence no need for NOHZ idle load
-	 * balancing:
+	 * balancing
 	 */
-	if (likely(!atomic_read(&nohz.nr_cpus)))
+	if (unlikely(!atomic_read(&nohz.nr_cpus)))
 		return;
 
 	if (rq->nr_running >= 2) {
-- 
2.51.0