[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <7876665.vgkxSAt2aO@vostro.rjw.lan>
Date: Sat, 16 Jan 2016 00:56:34 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Linux PM list <linux-pm@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...nel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Sudeep Holla <sudeep.holla@....com>
Subject: [PATCH 2/2] cpuidle: menu: Avoid pointless checks in menu_select()
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
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@...el.com>
---
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];
Powered by blists - more mailing lists