linux-kernel - [tip: sched/core] sched/fair: Small cleanup to update_newidle

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Message-ID: <176312274090.498.11478237853387689367.tip-bot2@tip-bot2>
Date: Fri, 14 Nov 2025 12:19:00 -0000
From: "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Dietmar Eggemann <dietmar.eggemann@....com>, Chris Mason <clm@...a.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/fair: Small cleanup to update_newidle_cost()

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

Commit-ID:     5a1cbf5ce1445d0173fa1c850b653ecf2034054e
Gitweb:        https://git.kernel.org/tip/5a1cbf5ce1445d0173fa1c850b653ecf2034054e
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Fri, 07 Nov 2025 17:01:27 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 14 Nov 2025 13:03:07 +01:00

sched/fair: Small cleanup to update_newidle_cost()

Simplify code by adding a few variables.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@....com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@....com>
Tested-by: Chris Mason <clm@...a.com>
Link: https://patch.msgid.link/20251107161739.655208666@infradead.org
---
 kernel/sched/fair.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2870523..50461c9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12225,22 +12225,25 @@ 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 		 * it is not outdated and the current max cost is actually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;
 	}