[PATCH 3/4] sched/fair: Small cleanup to update_newidle_cost()

Peter Zijlstra
2025-11-07T16:18:19Z

Simplify code by adding a few variables.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/sched/fair.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12148,22 +12148,25 @@ 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* it is not outdated and the current max cost is actually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;
}