diff options
Diffstat (limited to 'drivers/cpuidle/governors/menu.c')
| -rw-r--r-- | drivers/cpuidle/governors/menu.c | 75 |
1 files changed, 44 insertions, 31 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index cf7f2f0e4ef5..71b523293354 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -122,9 +122,8 @@ struct menu_device { int last_state_idx; int needs_update; - unsigned int expected_us; + unsigned int next_timer_us; unsigned int predicted_us; - unsigned int exit_us; unsigned int bucket; unsigned int correction_factor[BUCKETS]; unsigned int intervals[INTERVALS]; @@ -257,7 +256,7 @@ again: stddev = int_sqrt(stddev); if (((avg > stddev * 6) && (divisor * 4 >= INTERVALS * 3)) || stddev <= 20) { - if (data->expected_us > avg) + if (data->next_timer_us > avg) data->predicted_us = avg; return; } @@ -289,7 +288,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) struct menu_device *data = &__get_cpu_var(menu_devices); int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); int i; - int multiplier; + unsigned int interactivity_req; struct timespec t; if (data->needs_update) { @@ -298,7 +297,6 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) } data->last_state_idx = 0; - data->exit_us = 0; /* Special case when user has set very strict latency requirement */ if (unlikely(latency_req == 0)) @@ -306,13 +304,11 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) /* determine the expected residency time, round up */ t = ktime_to_timespec(tick_nohz_get_sleep_length()); - data->expected_us = + data->next_timer_us = t.tv_sec * USEC_PER_SEC + t.tv_nsec / NSEC_PER_USEC; - data->bucket = which_bucket(data->expected_us); - - multiplier = performance_multiplier(); + data->bucket = which_bucket(data->next_timer_us); /* * if the correction factor is 0 (eg first time init or cpu hotplug @@ -326,17 +322,26 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) * operands are 32 bits. * Make sure to round up for half microseconds. */ - data->predicted_us = div_round64((uint64_t)data->expected_us * + data->predicted_us = div_round64((uint64_t)data->next_timer_us * data->correction_factor[data->bucket], RESOLUTION * DECAY); get_typical_interval(data); /* + * Performance multiplier defines a minimum predicted idle + * duration / latency ratio. Adjust the latency limit if + * necessary. + */ + interactivity_req = data->predicted_us / performance_multiplier(); + if (latency_req > interactivity_req) + latency_req = interactivity_req; + + /* * We want to default to C1 (hlt), not to busy polling * unless the timer is happening really really soon. */ - if (data->expected_us > 5 && + if (data->next_timer_us > 5 && !drv->states[CPUIDLE_DRIVER_STATE_START].disabled && dev->states_usage[CPUIDLE_DRIVER_STATE_START].disable == 0) data->last_state_idx = CPUIDLE_DRIVER_STATE_START; @@ -355,11 +360,8 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) continue; if (s->exit_latency > latency_req) continue; - if (s->exit_latency * multiplier > data->predicted_us) - continue; data->last_state_idx = i; - data->exit_us = s->exit_latency; } return data->last_state_idx; @@ -390,36 +392,47 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) { struct menu_device *data = &__get_cpu_var(menu_devices); int last_idx = data->last_state_idx; - unsigned int last_idle_us = cpuidle_get_last_residency(dev); struct cpuidle_state *target = &drv->states[last_idx]; unsigned int measured_us; unsigned int new_factor; /* - * Ugh, this idle state doesn't support residency measurements, so we - * are basically lost in the dark. As a compromise, assume we slept - * for the whole expected time. + * Try to figure out how much time passed between entry to low + * power state and occurrence of the wakeup event. + * + * If the entered idle state didn't support residency measurements, + * we are basically lost in the dark how much time passed. + * As a compromise, assume we slept for the whole expected time. + * + * Any measured amount of time will include the exit latency. + * Since we are interested in when the wakeup begun, not when it + * was completed, we must substract the exit latency. However, if + * the measured amount of time is less than the exit latency, + * assume the state was never reached and the exit latency is 0. */ - if (unlikely(!(target->flags & CPUIDLE_FLAG_TIME_VALID))) - last_idle_us = data->expected_us; + if (unlikely(!(target->flags & CPUIDLE_FLAG_TIME_VALID))) { + /* Use timer value as is */ + measured_us = data->next_timer_us; + } else { + /* Use measured value */ + measured_us = cpuidle_get_last_residency(dev); - measured_us = last_idle_us; - - /* - * We correct for the exit latency; we are assuming here that the - * exit latency happens after the event that we're interested in. - */ - if (measured_us > data->exit_us) - measured_us -= data->exit_us; + /* Deduct exit latency */ + if (measured_us > target->exit_latency) + measured_us -= target->exit_latency; + /* Make sure our coefficients do not exceed unity */ + if (measured_us > data->next_timer_us) + measured_us = data->next_timer_us; + } /* Update our correction ratio */ new_factor = data->correction_factor[data->bucket]; new_factor -= new_factor / DECAY; - if (data->expected_us > 0 && measured_us < MAX_INTERESTING) - new_factor += RESOLUTION * measured_us / data->expected_us; + if (data->next_timer_us > 0 && measured_us < MAX_INTERESTING) + new_factor += RESOLUTION * measured_us / data->next_timer_us; else /* * we were idle so long that we count it as a perfect @@ -439,7 +452,7 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) data->correction_factor[data->bucket] = new_factor; /* update the repeating-pattern data */ - data->intervals[data->interval_ptr++] = last_idle_us; + data->intervals[data->interval_ptr++] = measured_us; if (data->interval_ptr >= INTERVALS) data->interval_ptr = 0; } |