Commit 5bb1729c authored Jan 16, 2016 by Rafael J. Wysocki

cpuidle: menu: Avoid pointless checks in menu_select()



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@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>

parent 51164251

drivers/cpuidle/governors/menu.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -342,7 +342,7 @@ static int menu_select(struct cpuidle_driver drv, struct cpuidle_device dev)
		* 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];