diff options
Diffstat (limited to 'drivers/cpuidle')
| -rw-r--r-- | drivers/cpuidle/governors/menu.c | 75 |
1 files changed, 70 insertions, 5 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 5b1f2c3..37c0ff6 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -28,6 +28,13 @@ #define MAX_INTERESTING 50000 #define STDDEV_THRESH 400 +/* 60 * 60 > STDDEV_THRESH * INTERVALS = 400 * 8 */ +#define MAX_DEVIATION 60 + +static DEFINE_PER_CPU(struct hrtimer, menu_hrtimer); +static DEFINE_PER_CPU(int, hrtimer_status); +/* menu hrtimer mode */ +enum {MENU_HRTIMER_STOP, MENU_HRTIMER_REPEAT}; /* * Concepts and ideas behind the menu governor @@ -191,17 +198,42 @@ static u64 div_round64(u64 dividend, u32 divisor) return div_u64(dividend + (divisor / 2), divisor); } +/* Cancel the hrtimer if it is not triggered yet */ +void menu_hrtimer_cancel(void) +{ + int cpu = smp_processor_id(); + struct hrtimer *hrtmr = &per_cpu(menu_hrtimer, cpu); + + /* The timer is still not time out*/ + if (per_cpu(hrtimer_status, cpu)) { + hrtimer_cancel(hrtmr); + per_cpu(hrtimer_status, cpu) = MENU_HRTIMER_STOP; + } +} +EXPORT_SYMBOL_GPL(menu_hrtimer_cancel); + +/* Call back for hrtimer is triggered */ +static enum hrtimer_restart menu_hrtimer_notify(struct hrtimer *hrtimer) +{ + int cpu = smp_processor_id(); + + per_cpu(hrtimer_status, cpu) = MENU_HRTIMER_STOP; + + return HRTIMER_NORESTART; +} + /* * Try detecting repeating patterns by keeping track of the last 8 * intervals, and checking if the standard deviation of that set * of points is below a threshold. If it is... then use the * average of these 8 points as the estimated value. */ -static void detect_repeating_patterns(struct menu_device *data) +static int detect_repeating_patterns(struct menu_device *data) { int i; uint64_t avg = 0; uint64_t stddev = 0; /* contains the square of the std deviation */ + int ret = 0; /* first calculate average and standard deviation of the past */ for (i = 0; i < INTERVALS; i++) @@ -210,7 +242,7 @@ static void detect_repeating_patterns(struct menu_device *data) /* if the avg is beyond the known next tick, it's worthless */ if (avg > data->expected_us) - return; + return 0; for (i = 0; i < INTERVALS; i++) stddev += (data->intervals[i] - avg) * @@ -223,8 +255,12 @@ static void detect_repeating_patterns(struct menu_device *data) * repeating pattern and predict we keep doing this. */ - if (avg && stddev < STDDEV_THRESH) + if (avg && stddev < STDDEV_THRESH) { data->predicted_us = avg; + ret = 1; + } + + return ret; } /** @@ -240,6 +276,9 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) int i; int multiplier; struct timespec t; + int repeat = 0, low_predicted = 0; + int cpu = smp_processor_id(); + struct hrtimer *hrtmr = &per_cpu(menu_hrtimer, cpu); if (data->needs_update) { menu_update(drv, dev); @@ -274,7 +313,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) data->predicted_us = div_round64(data->expected_us * data->correction_factor[data->bucket], RESOLUTION * DECAY); - detect_repeating_patterns(data); + repeat = detect_repeating_patterns(data); /* * We want to default to C1 (hlt), not to busy polling @@ -295,8 +334,10 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) if (s->disabled || su->disable) continue; - if (s->target_residency > data->predicted_us) + if (s->target_residency > data->predicted_us) { + low_predicted = 1; continue; + } if (s->exit_latency > latency_req) continue; if (s->exit_latency * multiplier > data->predicted_us) @@ -309,6 +350,27 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) } } + /* not deepest C-state chosen for low predicted residency */ + if (low_predicted) { + unsigned int timer_us = 0; + + /* + * Set a timer to detect whether this sleep is much + * longer than repeat mode predicted. If the timer + * triggers, the code will evaluate whether to put + * the CPU into a deeper C-state. + * The timer is cancelled on CPU wakeup. + */ + timer_us = 2 * (data->predicted_us + MAX_DEVIATION); + + if (repeat && (4 * timer_us < data->expected_us)) { + hrtimer_start(hrtmr, ns_to_ktime(1000 * timer_us), + HRTIMER_MODE_REL_PINNED); + /* In repeat case, menu hrtimer is started */ + per_cpu(hrtimer_status, cpu) = MENU_HRTIMER_REPEAT; + } + } + return data->last_state_idx; } @@ -399,6 +461,9 @@ static int menu_enable_device(struct cpuidle_driver *drv, struct cpuidle_device *dev) { struct menu_device *data = &per_cpu(menu_devices, dev->cpu); + struct hrtimer *t = &per_cpu(menu_hrtimer, dev->cpu); + hrtimer_init(t, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + t->function = menu_hrtimer_notify; memset(data, 0, sizeof(struct menu_device)); |
