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cpuidle: enter_state: Don't needlessly calculate diff time

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Currently, ktime_us_delta() is invoked unconditionally to compute the
idle residency of the CPU, but it only makes sense to do that if a
valid idle state has been entered, so move the ktime_us_delta()
invocation after the entered_state >= 0 check.

While at it, merge two comment blocks in there into one and drop
a space between type casting of diff.

This patch has no functional changes.

Signed-off-by: Fieah Lim <kw@fieahl.im>
[ rjw: Changelog cleanup, comment format fix ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Fieah Lim 2018-09-11 05:47:25 +08:00 committed by Rafael J. Wysocki
parent 6a5f95b5a4
commit 7037b43e00
1 changed files with 8 additions and 8 deletions
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16
drivers/cpuidle/cpuidle.c
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@ -247,17 +247,17 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
if (!cpuidle_state_is_coupled(drv, index)) if (!cpuidle_state_is_coupled(drv, index))
local_irq_enable(); local_irq_enable();
diff = ktime_us_delta(time_end, time_start);
if (diff > INT_MAX)
diff = INT_MAX;
dev->last_residency = (int) diff;
if (entered_state >= 0) { if (entered_state >= 0) {
/* Update cpuidle counters */ /*
/* This can be moved to within driver enter routine * Update cpuidle counters
* This can be moved to within driver enter routine,
* but that results in multiple copies of same code. * but that results in multiple copies of same code.
*/ */
diff = ktime_us_delta(time_end, time_start);
if (diff > INT_MAX)
diff = INT_MAX;
dev->last_residency = (int)diff;
dev->states_usage[entered_state].time += dev->last_residency; dev->states_usage[entered_state].time += dev->last_residency;
dev->states_usage[entered_state].usage++; dev->states_usage[entered_state].usage++;
} else { } else {