diff options
Diffstat (limited to 'drivers/cpuidle')
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 16 | ||||
| -rw-r--r-- | drivers/cpuidle/governors/ladder.c | 2 | ||||
| -rw-r--r-- | drivers/cpuidle/governors/menu.c | 114 | ||||
| -rw-r--r-- | drivers/cpuidle/poll_state.c | 8 |
4 files changed, 80 insertions, 60 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 6df894d..4a97446 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -247,17 +247,17 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, if (!cpuidle_state_is_coupled(drv, index)) local_irq_enable(); - diff = ktime_us_delta(time_end, time_start); - if (diff > INT_MAX) - diff = INT_MAX; - - dev->last_residency = (int) diff; - if (entered_state >= 0) { - /* Update cpuidle counters */ - /* This can be moved to within driver enter routine + /* + * Update cpuidle counters + * This can be moved to within driver enter routine, * but that results in multiple copies of same code. */ + diff = ktime_us_delta(time_end, time_start); + if (diff > INT_MAX) + diff = INT_MAX; + + dev->last_residency = (int)diff; dev->states_usage[entered_state].time += dev->last_residency; dev->states_usage[entered_state].usage++; } else { diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c index 704880a..f0dddc6 100644 --- a/drivers/cpuidle/governors/ladder.c +++ b/drivers/cpuidle/governors/ladder.c @@ -80,7 +80,7 @@ static int ladder_select_state(struct cpuidle_driver *drv, last_state = &ldev->states[last_idx]; - last_residency = cpuidle_get_last_residency(dev) - drv->states[last_idx].exit_latency; + last_residency = dev->last_residency - drv->states[last_idx].exit_latency; /* consider promotion */ if (last_idx < drv->state_count - 1 && diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index e26a409..575a68f 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -124,7 +124,6 @@ struct menu_device { int tick_wakeup; unsigned int next_timer_us; - unsigned int predicted_us; unsigned int bucket; unsigned int correction_factor[BUCKETS]; unsigned int intervals[INTERVALS]; @@ -197,10 +196,11 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev); * of points is below a threshold. If it is... then use the * average of these 8 points as the estimated value. */ -static unsigned int get_typical_interval(struct menu_device *data) +static unsigned int get_typical_interval(struct menu_device *data, + unsigned int predicted_us) { int i, divisor; - unsigned int max, thresh, avg; + unsigned int min, max, thresh, avg; uint64_t sum, variance; thresh = UINT_MAX; /* Discard outliers above this value */ @@ -208,6 +208,7 @@ static unsigned int get_typical_interval(struct menu_device *data) again: /* First calculate the average of past intervals */ + min = UINT_MAX; max = 0; sum = 0; divisor = 0; @@ -218,8 +219,19 @@ again: divisor++; if (value > max) max = value; + + if (value < min) + min = value; } } + + /* + * If the result of the computation is going to be discarded anyway, + * avoid the computation altogether. + */ + if (min >= predicted_us) + return UINT_MAX; + if (divisor == INTERVALS) avg = sum >> INTERVAL_SHIFT; else @@ -286,10 +298,9 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, struct menu_device *data = this_cpu_ptr(&menu_devices); int latency_req = cpuidle_governor_latency_req(dev->cpu); int i; - int first_idx; int idx; unsigned int interactivity_req; - unsigned int expected_interval; + unsigned int predicted_us; unsigned long nr_iowaiters, cpu_load; ktime_t delta_next; @@ -298,50 +309,36 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, data->needs_update = 0; } - /* Special case when user has set very strict latency requirement */ - if (unlikely(latency_req == 0)) { - *stop_tick = false; - return 0; - } - /* determine the expected residency time, round up */ data->next_timer_us = ktime_to_us(tick_nohz_get_sleep_length(&delta_next)); get_iowait_load(&nr_iowaiters, &cpu_load); data->bucket = which_bucket(data->next_timer_us, nr_iowaiters); + if (unlikely(drv->state_count <= 1 || latency_req == 0) || + ((data->next_timer_us < drv->states[1].target_residency || + latency_req < drv->states[1].exit_latency) && + !drv->states[0].disabled && !dev->states_usage[0].disable)) { + /* + * In this case state[0] will be used no matter what, so return + * it right away and keep the tick running. + */ + *stop_tick = false; + return 0; + } + /* * Force the result of multiplication to be 64 bits even if both * operands are 32 bits. * Make sure to round up for half microseconds. */ - data->predicted_us = DIV_ROUND_CLOSEST_ULL((uint64_t)data->next_timer_us * + predicted_us = DIV_ROUND_CLOSEST_ULL((uint64_t)data->next_timer_us * data->correction_factor[data->bucket], RESOLUTION * DECAY); - - expected_interval = get_typical_interval(data); - expected_interval = min(expected_interval, data->next_timer_us); - - first_idx = 0; - if (drv->states[0].flags & CPUIDLE_FLAG_POLLING) { - struct cpuidle_state *s = &drv->states[1]; - unsigned int polling_threshold; - - /* - * 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 && - latency_req > s->exit_latency && !s->disabled && - !dev->states_usage[1].disable) - first_idx = 1; - } - /* * Use the lowest expected idle interval to pick the idle state. */ - data->predicted_us = min(data->predicted_us, expected_interval); + predicted_us = min(predicted_us, get_typical_interval(data, predicted_us)); if (tick_nohz_tick_stopped()) { /* @@ -352,34 +349,46 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, * the known time till the closest timer event for the idle * state selection. */ - if (data->predicted_us < TICK_USEC) - data->predicted_us = ktime_to_us(delta_next); + if (predicted_us < TICK_USEC) + predicted_us = ktime_to_us(delta_next); } else { /* * Use the performance multiplier and the user-configurable * latency_req to determine the maximum exit latency. */ - interactivity_req = data->predicted_us / performance_multiplier(nr_iowaiters, cpu_load); + interactivity_req = predicted_us / performance_multiplier(nr_iowaiters, cpu_load); if (latency_req > interactivity_req) latency_req = interactivity_req; } - expected_interval = data->predicted_us; /* * Find the idle state with the lowest power while satisfying * our constraints. */ idx = -1; - for (i = first_idx; i < drv->state_count; i++) { + for (i = 0; i < drv->state_count; i++) { struct cpuidle_state *s = &drv->states[i]; struct cpuidle_state_usage *su = &dev->states_usage[i]; if (s->disabled || su->disable) continue; + if (idx == -1) idx = i; /* first enabled state */ - if (s->target_residency > data->predicted_us) { - if (data->predicted_us < TICK_USEC) + + if (s->target_residency > predicted_us) { + /* + * Use a physical idle state, not busy polling, unless + * a timer is going to trigger soon enough. + */ + if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && + s->exit_latency <= latency_req && + s->target_residency <= data->next_timer_us) { + predicted_us = s->target_residency; + idx = i; + break; + } + if (predicted_us < TICK_USEC) break; if (!tick_nohz_tick_stopped()) { @@ -389,7 +398,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, * tick in that case and let the governor run * again in the next iteration of the loop. */ - expected_interval = drv->states[idx].target_residency; + predicted_us = drv->states[idx].target_residency; break; } @@ -403,7 +412,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, s->target_residency <= ktime_to_us(delta_next)) idx = i; - goto out; + return idx; } if (s->exit_latency > latency_req) { /* @@ -412,7 +421,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, * expected idle duration so that the tick is retained * as long as that target residency is low enough. */ - expected_interval = drv->states[idx].target_residency; + predicted_us = drv->states[idx].target_residency; break; } idx = i; @@ -426,7 +435,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, * expected idle duration is shorter than the tick period length. */ if (((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) || - expected_interval < TICK_USEC) && !tick_nohz_tick_stopped()) { + predicted_us < TICK_USEC) && !tick_nohz_tick_stopped()) { unsigned int delta_next_us = ktime_to_us(delta_next); *stop_tick = false; @@ -450,10 +459,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, } } -out: - data->last_state_idx = idx; - - return data->last_state_idx; + return idx; } /** @@ -512,9 +518,19 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) * duration predictor do a better job next time. */ measured_us = 9 * MAX_INTERESTING / 10; + } else if ((drv->states[last_idx].flags & CPUIDLE_FLAG_POLLING) && + dev->poll_time_limit) { + /* + * The CPU exited the "polling" state due to a time limit, so + * the idle duration prediction leading to the selection of that + * state was inaccurate. If a better prediction had been made, + * the CPU might have been woken up from idle by the next timer. + * Assume that to be the case. + */ + measured_us = data->next_timer_us; } else { /* measured value */ - measured_us = cpuidle_get_last_residency(dev); + measured_us = dev->last_residency; /* Deduct exit latency */ if (measured_us > 2 * target->exit_latency) diff --git a/drivers/cpuidle/poll_state.c b/drivers/cpuidle/poll_state.c index 3f86d23..85792d3 100644 --- a/drivers/cpuidle/poll_state.c +++ b/drivers/cpuidle/poll_state.c @@ -9,7 +9,6 @@ #include <linux/sched/clock.h> #include <linux/sched/idle.h> -#define POLL_IDLE_TIME_LIMIT (TICK_NSEC / 16) #define POLL_IDLE_RELAX_COUNT 200 static int __cpuidle poll_idle(struct cpuidle_device *dev, @@ -17,8 +16,11 @@ static int __cpuidle poll_idle(struct cpuidle_device *dev, { u64 time_start = local_clock(); + dev->poll_time_limit = false; + local_irq_enable(); if (!current_set_polling_and_test()) { + u64 limit = (u64)drv->states[1].target_residency * NSEC_PER_USEC; unsigned int loop_count = 0; while (!need_resched()) { @@ -27,8 +29,10 @@ static int __cpuidle poll_idle(struct cpuidle_device *dev, continue; loop_count = 0; - if (local_clock() - time_start > POLL_IDLE_TIME_LIMIT) + if (local_clock() - time_start > limit) { + dev->poll_time_limit = true; break; + } } } current_clr_polling(); |
