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path: root/drivers/cpuidle/governors/menu.c
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Diffstat (limited to 'drivers/cpuidle/governors/menu.c')
-rw-r--r--drivers/cpuidle/governors/menu.c45
1 files changed, 28 insertions, 17 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 1aef60d160eb..110483f0e3fb 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -328,9 +328,8 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
unsigned int polling_threshold;
/*
- * We want to default to C1 (hlt), not to busy polling
- * unless the timer is happening really really soon, or
- * C1's exit latency exceeds the user configured limit.
+ * Default to a physical idle state, not to busy polling, unless
+ * a timer is going to trigger really really soon.
*/
polling_threshold = max_t(unsigned int, 20, s->target_residency);
if (data->next_timer_us > polling_threshold &&
@@ -349,14 +348,12 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
* If the tick is already stopped, the cost of possible short
* idle duration misprediction is much higher, because the CPU
* may be stuck in a shallow idle state for a long time as a
- * result of it. In that case say we might mispredict and try
- * to force the CPU into a state for which we would have stopped
- * the tick, unless a timer is going to expire really soon
- * anyway.
+ * result of it. In that case say we might mispredict and use
+ * the known time till the closest timer event for the idle
+ * state selection.
*/
if (data->predicted_us < TICK_USEC)
- data->predicted_us = min_t(unsigned int, TICK_USEC,
- ktime_to_us(delta_next));
+ data->predicted_us = ktime_to_us(delta_next);
} else {
/*
* Use the performance multiplier and the user-configurable
@@ -381,8 +378,22 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
continue;
if (idx == -1)
idx = i; /* first enabled state */
- if (s->target_residency > data->predicted_us)
- break;
+ if (s->target_residency > data->predicted_us) {
+ if (!tick_nohz_tick_stopped())
+ break;
+
+ /*
+ * If the state selected so far is shallow and this
+ * state's target residency matches the time till the
+ * closest timer event, select this one to avoid getting
+ * stuck in the shallow one for too long.
+ */
+ if (drv->states[idx].target_residency < TICK_USEC &&
+ s->target_residency <= ktime_to_us(delta_next))
+ idx = i;
+
+ goto out;
+ }
if (s->exit_latency > latency_req) {
/*
* If we break out of the loop for latency reasons, use
@@ -403,14 +414,13 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
* Don't stop the tick if the selected state is a polling one or if the
* expected idle duration is shorter than the tick period length.
*/
- if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) ||
- expected_interval < TICK_USEC) {
+ if (((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) ||
+ expected_interval < TICK_USEC) && !tick_nohz_tick_stopped()) {
unsigned int delta_next_us = ktime_to_us(delta_next);
*stop_tick = false;
- if (!tick_nohz_tick_stopped() && idx > 0 &&
- drv->states[idx].target_residency > delta_next_us) {
+ if (idx > 0 && drv->states[idx].target_residency > delta_next_us) {
/*
* The tick is not going to be stopped and the target
* residency of the state to be returned is not within
@@ -418,8 +428,8 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
* tick, so try to correct that.
*/
for (i = idx - 1; i >= 0; i--) {
- if (drv->states[i].disabled ||
- dev->states_usage[i].disable)
+ if (drv->states[i].disabled ||
+ dev->states_usage[i].disable)
continue;
idx = i;
@@ -429,6 +439,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
}
}
+out:
data->last_state_idx = idx;
return data->last_state_idx;