linux-kernel - [PATCH 3/5] x86,idle: Reset correction factor

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Date:	Tue, 16 Oct 2012 21:04:38 -0400
From:	Youquan Song <youquan.song@...el.com>
To:	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	arjan@...ux.intel.com, lenb@...nel.org
Cc:	Rik van Riel <riel@...hat.com>,
	Youquan Song <youquan.song@...ux.intel.com>,
	Youquan Song <youquan.song@...el.com>
Subject: [PATCH 3/5] x86,idle: Reset correction factor

In general case, the expected residency is much larger than deepest C-state
target residency, but prediction logic still predicts the small predicted
residency, so the prediction history is totally broken. In this situation,
reset the correction factor is the only choice.

Signed-off-by: Youquan Song <youquan.song@...el.com>
Signed-off-by: Rik van Riel <riel@...hat.com>
---
 drivers/cpuidle/governors/menu.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index b34bf11..7dbac97 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -221,6 +221,10 @@ EXPORT_SYMBOL_GPL(menu_hrtimer_cancel);
 static enum hrtimer_restart menu_hrtimer_notify(struct hrtimer *hrtimer)
 {
 	int cpu = smp_processor_id();
+	struct menu_device *data = &per_cpu(menu_devices, cpu);
+
+	if (per_cpu(hrtimer_started, cpu) == 2)
+		data->correction_factor[data->bucket] = RESOLUTION * DECAY;
 
 	per_cpu(hrtimer_started, cpu) = 0;
 
@@ -386,7 +390,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 			hrtimer_start(hrtmr, ns_to_ktime(1000 * timer_us),
 				HRTIMER_MODE_REL_PINNED);
 			/* menu hrtimer is started */
-			per_cpu(hrtimer_started, cpu) = 1;
+			per_cpu(hrtimer_started, cpu) = 2;
 		}
 
 	}
-- 
1.7.7.4

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