[PATCH 2/2] cpuidle: menu: Avoid pointless checks in menu_select()

From: Rafael J. Wysocki
Date: Fri Jan 15 2016 - 18:57:24 EST

From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Subject: [PATCH]

If menu_select() cannot find a suitable state to return, it will
return the state index stored in data->last_state_idx. This
means that it is pointless to look at the states whose indices
are less than or equal to data->last_state_idx in the main loop,
so don't do that.

Given that those checks are done on every idle state selection, this
change can save quite a bit of completely unnecessary overhead.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
drivers/cpuidle/governors/menu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-pm/drivers/cpuidle/governors/menu.c
--- linux-pm.orig/drivers/cpuidle/governors/menu.c
+++ linux-pm/drivers/cpuidle/governors/menu.c
@@ -342,7 +342,7 @@ static int menu_select(struct cpuidle_dr
* Find the idle state with the lowest power while satisfying
* our constraints.
- for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
+ for (i = data->last_state_idx + 1; i < drv->state_count; i++) {
struct cpuidle_state *s = &drv->states[i];
struct cpuidle_state_usage *su = &dev->states_usage[i];