linux-kernel - [PATCH 1/8] Cpuidle: Ignore interval prediction result when timer is shorter

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Date:	Wed, 14 Aug 2013 19:02:34 +0300
From:	tuukka.tikkanen@...aro.org
To:	rjw@...k.pl, daniel.lezcano@...aro.org, linux-pm@...r.kernel.org
Cc:	private-pmwg@...aro.org, linux-kernel@...r.kernel.org,
	Tuukka Tikkanen <tuukka.tikkanen@...aro.org>
Subject: [PATCH 1/8] Cpuidle: Ignore interval prediction result when timer is shorter

From: Tuukka Tikkanen <tuukka.tikkanen@...aro.org>

This patch prevents cpuidle menu governor from using repeating interval
prediction result if the idle period predicted is longer than the one
allowed by shortest running timer.

Signed-off-by: Tuukka Tikkanen <tuukka.tikkanen@...aro.org>
---
 drivers/cpuidle/governors/menu.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index bc580b6..c8ab1c5 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -238,10 +238,13 @@ again:
 	 *
 	 * The typical interval is obtained when standard deviation is small
 	 * or standard deviation is small compared to the average interval.
+	 *
+	 * Use this result only if there is no timer to wake us up sooner.
 	 */
 	if (((avg > stddev * 6) && (divisor * 4 >= INTERVALS * 3))
 							|| stddev <= 20) {
-		data->predicted_us = avg;
+		if (data->expected_us > avg)
+			data->predicted_us = avg;
 		return;
 
 	} else if ((divisor * 4) > INTERVALS * 3) {
-- 
1.7.9.5

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