cpuidle: menu: Optimize bucket assignment when next_timer_ns equals KTIME_MAX

Zhongqiu Han · rafaeljw · commit d4a7882f93bf · 2025-04-09T19:37:30.000+02:00
Directly assign the last bucket value instead of calling which_bucket() when next_timer_ns equals KTIME_MAX, the largest possible value that always falls into the last bucket. This avoids unnecessary calculations and enhances performance. Reviewed-by: Christian Loehle <christian.loehle@arm.com> Signed-off-by: Zhongqiu Han <quic_zhonhan@quicinc.com> Link: https://patch.msgid.link/20250405135308.1854342-1-quic_zhonhan@quicinc.com Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
@@ -255,7 +255,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 		 */
 		data->next_timer_ns = KTIME_MAX;
 		delta_tick = TICK_NSEC / 2;
-		data->bucket = which_bucket(KTIME_MAX);
+		data->bucket = BUCKETS - 1;
 	}
 
 	if (unlikely(drv->state_count <= 1 || latency_req == 0) ||

Original file line number	Diff line number	Diff line change
`@@ -255,7 +255,7 @@ static int menu_select(struct cpuidle_driver drv, struct cpuidle_device dev,`
`255`	`255`	`*/`
`256`	`256`	`data->next_timer_ns = KTIME_MAX;`
`257`	`257`	`delta_tick = TICK_NSEC / 2;`
`258`		`- data->bucket = which_bucket(KTIME_MAX);`
	`258`	`+ data->bucket = BUCKETS - 1;`
`259`	`259`	`}`
`260`	`260`
`261`	`261`	`if (unlikely(drv->state_count <= 1 \|\| latency_req == 0) \|\|`