[tip: sched/core] sched/fair: Small cleanup to update_newidle_cost()

tip-bot2 for Peter Zijlstra
2025-11-17T16:23:34Z

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

Commit-ID: 08d473dd8718e4a4d698b1113a14a40ad64a909b
Gitweb: https://git.kernel.org/tip/08d473dd8718e4a4d698b1113a14a40ad64a909b
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Fri, 07 Nov 2025 17:01:27 +01:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 17 Nov 2025 17:13:15 +01:00

sched/fair: Small cleanup to update_newidle_cost()

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
---
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 75f891d..abcbb67 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12226,22 +12226,25 @@ 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* it is not outdated and the current max cost is actually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;
}