[PATCH V2 14/16] cpuidle: don't calculate time-diff if entered_state < 0

From: Viresh Kumar
Date: Thu Oct 03 2013 - 11:58:40 EST


If entered_state < 0, we don't need to set dev->last_residency to 'diff' as we
will be setting it to zero without using its new value.

And so move calculation of diff also inside the "if" statement.

Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
drivers/cpuidle/cpuidle.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index b45257a..1a6e9f5 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -77,23 +77,22 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,

struct cpuidle_state *target_state = &drv->states[index];
ktime_t time_start, time_end;
- s64 diff;

time_start = ktime_get();

entered_state = target_state->enter(dev, drv, index);

- time_end = ktime_get();
+ if (entered_state >= 0) {
+ s64 diff;

- local_irq_enable();
+ time_end = ktime_get();
+ diff = ktime_to_us(ktime_sub(time_end, time_start));

- diff = ktime_to_us(ktime_sub(time_end, time_start));
- if (diff > INT_MAX)
- diff = INT_MAX;
+ if (diff > INT_MAX)
+ diff = INT_MAX;

- dev->last_residency = (int) diff;
+ dev->last_residency = (int) diff;

- if (entered_state >= 0) {
/* Update cpuidle counters */
/* This can be moved to within driver enter routine
* but that results in multiple copies of same code.
@@ -104,6 +103,8 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
dev->last_residency = 0;
}

+ local_irq_enable();
+
return entered_state;
}

--
1.7.12.rc2.18.g61b472e

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