diff --git a/drivers/cpuidle/governors/gov.h b/drivers/cpuidle/governors/gov.h index 99e067d9668c..cd06a2e7b506 100644 --- a/drivers/cpuidle/governors/gov.h +++ b/drivers/cpuidle/governors/gov.h @@ -10,5 +10,10 @@ * check the time till the closest expected timer event. */ #define RESIDENCY_THRESHOLD_NS (15 * NSEC_PER_USEC) +/* + * If the closest timer is in this range, the governor idle state selection need + * not be adjusted after the scheduler tick has been stopped. + */ +#define SAFE_TIMER_RANGE_NS (2 * TICK_NSEC) #endif /* __CPUIDLE_GOVERNOR_H */ diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 899ff16ff1fe..544a5d593007 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -261,13 +261,16 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, predicted_ns = min((u64)timer_us * NSEC_PER_USEC, predicted_ns); /* * 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 use - * the known time till the closest timer event for the idle - * state selection. + * idle duration misprediction is higher because the CPU may get + * stuck in a shallow idle state then. To avoid that, if + * predicted_ns is small enough, say it might be mispredicted + * and use the known time till the closest timer for idle state + * selection unless that timer is going to trigger within + * SAFE_TIMER_RANGE_NS in which case it can be regarded as a + * sufficient safety net. */ - if (tick_nohz_tick_stopped() && predicted_ns < TICK_NSEC) + if (tick_nohz_tick_stopped() && predicted_ns < TICK_NSEC && + data->next_timer_ns > SAFE_TIMER_RANGE_NS) predicted_ns = data->next_timer_ns; } else { /*