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authorvenkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com>2008-07-30 19:21:43 -0700
committerAndi Kleen <ak@linux.intel.com>2008-08-15 21:25:25 +0200
commit320eee776357db52d6fcfb11cff985b1976a4595 (patch)
tree29859b2e6209a35fc6a735fa4c195e7daeaa1b31 /drivers
parenta2bd92023357e47f22a34d4cb1635453546662bc (diff)
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/cpuidle/governors/menu.c31
1 files changed, 19 insertions, 12 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index b8f3e21530b..8d7cf3f3145 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -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;
}
}