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cpuidle: Menu governor fix wrong usage of measured_us 

There is a bug in menu governor where we have
		if (data->elapsed_us < data->elapsed_us + measured_us)

with measured_us already having elapsed_us added in tickless case here
	unsigned int measured_us =
		cpuidle_get_last_residency(dev) + data->elapsed_us;

Also, it should be last_residency, not measured_us, that need to be used to
do comparing and distinguish between expected & non-expected events.

Refactor menu_reflect() to fix these two problems.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Wei Gang <gang.wei@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
This commit is contained in:
venkatesh.pallipadi@intel.com 2008-07-30 19:21:43 -07:00 committed by Andi Kleen
parent a2bd920233
commit 320eee7763
1 changed files with 19 additions and 12 deletions
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31
drivers/cpuidle/governors/menu.c
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@ -74,9 +74,9 @@ static void menu_reflect(struct cpuidle_device *dev)
{
struct menu_device *data = &__get_cpu_var(menu_devices);
int last_idx = data->last_state_idx;
unsigned int measured_us =
cpuidle_get_last_residency(dev) + data->elapsed_us;
unsigned int last_idle_us = cpuidle_get_last_residency(dev);
struct cpuidle_state *target = &dev->states[last_idx];
unsigned int measured_us;
/*
* Ugh, this idle state doesn't support residency measurements, so we
@ -84,20 +84,27 @@ static void menu_reflect(struct cpuidle_device *dev)
* for one full standard timer tick. However, be aware that this
* could potentially result in a suboptimal state transition.
*/
if (!(target->flags & CPUIDLE_FLAG_TIME_VALID))
measured_us = USEC_PER_SEC / HZ;
if (unlikely(!(target->flags & CPUIDLE_FLAG_TIME_VALID)))
last_idle_us = USEC_PER_SEC / HZ;
/* Predict time remaining until next break event */
if (measured_us + BREAK_FUZZ < data->expected_us - target->exit_latency) {
data->predicted_us = max(measured_us, data->last_measured_us);
/*
* measured_us and elapsed_us are the cumulative idle time, since the
* last time we were woken out of idle by an interrupt.
*/
if (data->elapsed_us <= data->elapsed_us + last_idle_us)
measured_us = data->elapsed_us + last_idle_us;
else
measured_us = -1;
/* Predict time until next break event */
data->predicted_us = max(measured_us, data->last_measured_us);
if (last_idle_us + BREAK_FUZZ <
data->expected_us - target->exit_latency) {
data->last_measured_us = measured_us;
data->elapsed_us = 0;
} else {
if (data->elapsed_us < data->elapsed_us + measured_us)
data->elapsed_us = measured_us;
else
data->elapsed_us = -1;
data->predicted_us = max(measured_us, data->last_measured_us);
data->elapsed_us = measured_us;
}
}