From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 7 Nov 2025 16:01:27 +0000 (+0100)
Subject: sched/fair: Small cleanup to update_newidle_cost()
X-Git-Tag: v6.18.5~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d4ffb9ce8e6501bebbf833cd7ae3f34eab1f76ba;p=thirdparty%2Fkernel%2Fstable.git

sched/fair: Small cleanup to update_newidle_cost()

commit 08d473dd8718e4a4d698b1113a14a40ad64a909b upstream.

Simplify code by adding a few variables.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Chris Mason <clm@meta.com>
Link: https://patch.msgid.link/20251107161739.655208666@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3dd12dcf6e6d1..8369dadf19580 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12124,22 +12124,25 @@ void update_max_interval(void)
 
 static inline bool update_newidle_cost(struct sched_domain *sd, u64 cost)
 {
+	unsigned long next_decay = sd->last_decay_max_lb_cost + HZ;
+	unsigned long now = jiffies;
+
 	if (cost > sd->max_newidle_lb_cost) {
 		/*
 		 * Track max cost of a domain to make sure to not delay the
 		 * next wakeup on the CPU.
 		 */
 		sd->max_newidle_lb_cost = cost;
-		sd->last_decay_max_lb_cost = jiffies;
-	} else if (time_after(jiffies, sd->last_decay_max_lb_cost + HZ)) {
+		sd->last_decay_max_lb_cost = now;
+
+	} else if (time_after(now, next_decay)) {
 		/*
 		 * Decay the newidle max times by ~1% per second to ensure that
 		 * it is not outdated and the current max cost is actually
 		 * shorter.
 		 */
 		sd->max_newidle_lb_cost = (sd->max_newidle_lb_cost * 253) / 256;
-		sd->last_decay_max_lb_cost = jiffies;
-
+		sd->last_decay_max_lb_cost = now;
 		return true;
 	}