[PATCH 4/5] x86,idle: Set residency to 0 if target Cstate not enter

From: Youquan Song
Date: Tue Oct 16 2012 - 09:01:41 EST

When cpuidle governor choose a C-state to enter for idle CPU, but it notice that
there is tasks request to be executed. So the idle CPU will not really enter
the target C-state and go to run task.

In this situation, it will use the residency of previous really entered target
C-states. Obviously, it is not reasonable.

So, this patch fix it by set the target C-state residency to 0.

Signed-off-by: Youquan Song <youquan.song@xxxxxxxxx>
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
drivers/cpuidle/cpuidle.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index e28f6ea..01dca54 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -144,6 +144,10 @@ int cpuidle_idle_call(void)
/* ask the governor for the next state */
next_state = cpuidle_curr_governor->select(drv, dev);
if (need_resched()) {
+ dev->last_residency = 0;
+ /* give the governor an opportunity to reflect on the outcome */
+ if (cpuidle_curr_governor->reflect)
+ cpuidle_curr_governor->reflect(dev, next_state);
return 0;

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