diff options
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 10 | ||||
| -rw-r--r-- | drivers/cpuidle/governors/ladder.c | 3 | ||||
| -rw-r--r-- | drivers/cpuidle/governors/menu.c | 59 | ||||
| -rw-r--r-- | include/linux/cpuidle.h | 8 | ||||
| -rw-r--r-- | include/linux/tick.h | 2 | ||||
| -rw-r--r-- | kernel/sched/idle.c | 4 | ||||
| -rw-r--r-- | kernel/time/tick-sched.c | 20 |
7 files changed, 87 insertions, 19 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 0003e9a02637..6df894d65d9e 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -272,12 +272,18 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, * * @drv: the cpuidle driver * @dev: the cpuidle device + * @stop_tick: indication on whether or not to stop the tick * * Returns the index of the idle state. The return value must not be negative. + * + * The memory location pointed to by @stop_tick is expected to be written the + * 'false' boolean value if the scheduler tick should not be stopped before + * entering the returned state. */ -int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) +int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, + bool *stop_tick) { - return cpuidle_curr_governor->select(drv, dev); + return cpuidle_curr_governor->select(drv, dev, stop_tick); } /** diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c index 1ad8745fd6d6..b24883f85c99 100644 --- a/drivers/cpuidle/governors/ladder.c +++ b/drivers/cpuidle/governors/ladder.c @@ -63,9 +63,10 @@ static inline void ladder_do_selection(struct ladder_device *ldev, * ladder_select_state - selects the next state to enter * @drv: cpuidle driver * @dev: the CPU + * @dummy: not used */ static int ladder_select_state(struct cpuidle_driver *drv, - struct cpuidle_device *dev) + struct cpuidle_device *dev, bool *dummy) { struct ladder_device *ldev = this_cpu_ptr(&ladder_devices); struct device *device = get_cpu_device(dev->cpu); diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index aa390404e85f..f53a929bd2bd 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -123,6 +123,7 @@ struct menu_device { int last_state_idx; int needs_update; + int tick_wakeup; unsigned int next_timer_us; unsigned int predicted_us; @@ -279,8 +280,10 @@ again: * menu_select - selects the next idle state to enter * @drv: cpuidle driver containing state data * @dev: the CPU + * @stop_tick: indication on whether or not to stop the tick */ -static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) +static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, + bool *stop_tick) { struct menu_device *data = this_cpu_ptr(&menu_devices); struct device *device = get_cpu_device(dev->cpu); @@ -303,8 +306,10 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) latency_req = resume_latency; /* Special case when user has set very strict latency requirement */ - if (unlikely(latency_req == 0)) + 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()); @@ -354,6 +359,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) 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. @@ -369,15 +375,30 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) idx = i; /* first enabled state */ if (s->target_residency > data->predicted_us) break; - if (s->exit_latency > latency_req) + if (s->exit_latency > latency_req) { + /* + * If we break out of the loop for latency reasons, use + * the target residency of the selected state as the + * 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; break; - + } idx = i; } if (idx == -1) idx = 0; /* No states enabled. Must use 0. */ + /* + * 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) + *stop_tick = false; + data->last_state_idx = idx; return data->last_state_idx; @@ -397,6 +418,7 @@ static void menu_reflect(struct cpuidle_device *dev, int index) data->last_state_idx = index; data->needs_update = 1; + data->tick_wakeup = tick_nohz_idle_got_tick(); } /** @@ -427,14 +449,27 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) * assume the state was never reached and the exit latency is 0. */ - /* measured value */ - measured_us = cpuidle_get_last_residency(dev); - - /* Deduct exit latency */ - if (measured_us > 2 * target->exit_latency) - measured_us -= target->exit_latency; - else - measured_us /= 2; + if (data->tick_wakeup && data->next_timer_us > TICK_USEC) { + /* + * The nohz code said that there wouldn't be any events within + * the tick boundary (if the tick was stopped), but the idle + * duration predictor had a differing opinion. Since the CPU + * was woken up by a tick (that wasn't stopped after all), the + * predictor was not quite right, so assume that the CPU could + * have been idle long (but not forever) to help the idle + * duration predictor do a better job next time. + */ + measured_us = 9 * MAX_INTERESTING / 10; + } else { + /* measured value */ + measured_us = cpuidle_get_last_residency(dev); + + /* Deduct exit latency */ + if (measured_us > 2 * target->exit_latency) + measured_us -= target->exit_latency; + else + measured_us /= 2; + } /* Make sure our coefficients do not exceed unity */ if (measured_us > data->next_timer_us) diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index a806e94c482f..1eefabf1621f 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -135,7 +135,8 @@ extern bool cpuidle_not_available(struct cpuidle_driver *drv, struct cpuidle_device *dev); extern int cpuidle_select(struct cpuidle_driver *drv, - struct cpuidle_device *dev); + struct cpuidle_device *dev, + bool *stop_tick); extern int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev, int index); extern void cpuidle_reflect(struct cpuidle_device *dev, int index); @@ -167,7 +168,7 @@ static inline bool cpuidle_not_available(struct cpuidle_driver *drv, struct cpuidle_device *dev) {return true; } static inline int cpuidle_select(struct cpuidle_driver *drv, - struct cpuidle_device *dev) + struct cpuidle_device *dev, bool *stop_tick) {return -ENODEV; } static inline int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev, int index) @@ -250,7 +251,8 @@ struct cpuidle_governor { struct cpuidle_device *dev); int (*select) (struct cpuidle_driver *drv, - struct cpuidle_device *dev); + struct cpuidle_device *dev, + bool *stop_tick); void (*reflect) (struct cpuidle_device *dev, int index); }; diff --git a/include/linux/tick.h b/include/linux/tick.h index fccebfba167e..ef0717e5e526 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -120,6 +120,7 @@ extern void tick_nohz_idle_restart_tick(void); extern void tick_nohz_idle_enter(void); extern void tick_nohz_idle_exit(void); extern void tick_nohz_irq_exit(void); +extern bool tick_nohz_idle_got_tick(void); extern ktime_t tick_nohz_get_sleep_length(void); extern unsigned long tick_nohz_get_idle_calls(void); extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu); @@ -141,6 +142,7 @@ static inline void tick_nohz_idle_stop_tick(void) { } static inline void tick_nohz_idle_restart_tick(void) { } static inline void tick_nohz_idle_enter(void) { } static inline void tick_nohz_idle_exit(void) { } +static inline bool tick_nohz_idle_got_tick(void) { return false; } static inline ktime_t tick_nohz_get_sleep_length(void) { diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 4f64835d38a8..a966bd2a6fa0 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -183,13 +183,15 @@ static void cpuidle_idle_call(void) next_state = cpuidle_find_deepest_state(drv, dev); call_cpuidle(drv, dev, next_state); } else { + bool stop_tick = true; + tick_nohz_idle_stop_tick(); rcu_idle_enter(); /* * Ask the cpuidle framework to choose a convenient idle state. */ - next_state = cpuidle_select(drv, dev); + next_state = cpuidle_select(drv, dev, &stop_tick); entered_state = call_cpuidle(drv, dev, next_state); /* * Give the governor an opportunity to reflect on the outcome diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index f5d37788ea85..69fe113cfc7f 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -967,6 +967,20 @@ void tick_nohz_irq_exit(void) } /** + * tick_nohz_idle_got_tick - Check whether or not the tick handler has run + */ +bool tick_nohz_idle_got_tick(void) +{ + struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); + + if (ts->inidle > 1) { + ts->inidle = 1; + return true; + } + return false; +} + +/** * tick_nohz_get_sleep_length - return the length of the current sleep * * Called from power state control code with interrupts disabled @@ -1077,6 +1091,9 @@ static void tick_nohz_handler(struct clock_event_device *dev) struct pt_regs *regs = get_irq_regs(); ktime_t now = ktime_get(); + if (ts->inidle) + ts->inidle = 2; + dev->next_event = KTIME_MAX; tick_sched_do_timer(now); @@ -1174,6 +1191,9 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) struct pt_regs *regs = get_irq_regs(); ktime_t now = ktime_get(); + if (ts->inidle) + ts->inidle = 2; + tick_sched_do_timer(now); /* |