diff options
Diffstat (limited to 'drivers/cpuidle')
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 12 | ||||
| -rw-r--r-- | drivers/cpuidle/cpuidle.h | 1 | ||||
| -rw-r--r-- | drivers/cpuidle/driver.c | 16 | ||||
| -rw-r--r-- | drivers/cpuidle/governors/menu.c | 60 | ||||
| -rw-r--r-- | drivers/cpuidle/sysfs.c | 5 |
5 files changed, 83 insertions, 11 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 12fdd39..1994885 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -156,7 +156,7 @@ int cpuidle_enable_device(struct cpuidle_device *dev) if (dev->enabled) return 0; - if (!cpuidle_curr_driver || !cpuidle_curr_governor) + if (!cpuidle_get_driver() || !cpuidle_curr_governor) return -EIO; if (!dev->state_count) return -EINVAL; @@ -207,7 +207,7 @@ void cpuidle_disable_device(struct cpuidle_device *dev) { if (!dev->enabled) return; - if (!cpuidle_curr_driver || !cpuidle_curr_governor) + if (!cpuidle_get_driver() || !cpuidle_curr_governor) return; dev->enabled = 0; @@ -271,10 +271,11 @@ static int __cpuidle_register_device(struct cpuidle_device *dev) { int ret; struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); + struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); if (!sys_dev) return -EINVAL; - if (!try_module_get(cpuidle_curr_driver->owner)) + if (!try_module_get(cpuidle_driver->owner)) return -EINVAL; init_completion(&dev->kobj_unregister); @@ -284,7 +285,7 @@ static int __cpuidle_register_device(struct cpuidle_device *dev) per_cpu(cpuidle_devices, dev->cpu) = dev; list_add(&dev->device_list, &cpuidle_detected_devices); if ((ret = cpuidle_add_sysfs(sys_dev))) { - module_put(cpuidle_curr_driver->owner); + module_put(cpuidle_driver->owner); return ret; } @@ -325,6 +326,7 @@ EXPORT_SYMBOL_GPL(cpuidle_register_device); void cpuidle_unregister_device(struct cpuidle_device *dev) { struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); + struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); if (dev->registered == 0) return; @@ -340,7 +342,7 @@ void cpuidle_unregister_device(struct cpuidle_device *dev) cpuidle_resume_and_unlock(); - module_put(cpuidle_curr_driver->owner); + module_put(cpuidle_driver->owner); } EXPORT_SYMBOL_GPL(cpuidle_unregister_device); diff --git a/drivers/cpuidle/cpuidle.h b/drivers/cpuidle/cpuidle.h index 9476ba3..33e50d5 100644 --- a/drivers/cpuidle/cpuidle.h +++ b/drivers/cpuidle/cpuidle.h @@ -9,7 +9,6 @@ /* For internal use only */ extern struct cpuidle_governor *cpuidle_curr_governor; -extern struct cpuidle_driver *cpuidle_curr_driver; extern struct list_head cpuidle_governors; extern struct list_head cpuidle_detected_devices; extern struct mutex cpuidle_lock; diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c index 2257004..fd1601e 100644 --- a/drivers/cpuidle/driver.c +++ b/drivers/cpuidle/driver.c @@ -14,7 +14,7 @@ #include "cpuidle.h" -struct cpuidle_driver *cpuidle_curr_driver; +static struct cpuidle_driver *cpuidle_curr_driver; DEFINE_SPINLOCK(cpuidle_driver_lock); /** @@ -40,13 +40,25 @@ int cpuidle_register_driver(struct cpuidle_driver *drv) EXPORT_SYMBOL_GPL(cpuidle_register_driver); /** + * cpuidle_get_driver - return the current driver + */ +struct cpuidle_driver *cpuidle_get_driver(void) +{ + return cpuidle_curr_driver; +} +EXPORT_SYMBOL_GPL(cpuidle_get_driver); + +/** * cpuidle_unregister_driver - unregisters a driver * @drv: the driver */ void cpuidle_unregister_driver(struct cpuidle_driver *drv) { - if (!drv) + if (drv != cpuidle_curr_driver) { + WARN(1, "invalid cpuidle_unregister_driver(%s)\n", + drv->name); return; + } spin_lock(&cpuidle_driver_lock); cpuidle_curr_driver = NULL; diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index b81ad9c..52ff8aa 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -21,9 +21,12 @@ #include <linux/math64.h> #define BUCKETS 12 +#define INTERVALS 8 #define RESOLUTION 1024 -#define DECAY 4 +#define DECAY 8 #define MAX_INTERESTING 50000 +#define STDDEV_THRESH 400 + /* * Concepts and ideas behind the menu governor @@ -64,6 +67,16 @@ * indexed based on the magnitude of the expected duration as well as the * "is IO outstanding" property. * + * Repeatable-interval-detector + * ---------------------------- + * There are some cases where "next timer" is a completely unusable predictor: + * Those cases where the interval is fixed, for example due to hardware + * interrupt mitigation, but also due to fixed transfer rate devices such as + * mice. + * For this, we use a different predictor: We track the duration of the last 8 + * intervals and if the stand deviation of these 8 intervals is below a + * threshold value, we use the average of these intervals as prediction. + * * Limiting Performance Impact * --------------------------- * C states, especially those with large exit latencies, can have a real @@ -104,6 +117,8 @@ struct menu_device { unsigned int exit_us; unsigned int bucket; u64 correction_factor[BUCKETS]; + u32 intervals[INTERVALS]; + int interval_ptr; }; @@ -175,6 +190,42 @@ static u64 div_round64(u64 dividend, u32 divisor) return div_u64(dividend + (divisor / 2), divisor); } +/* + * 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) +{ + int i; + uint64_t avg = 0; + uint64_t stddev = 0; /* contains the square of the std deviation */ + + /* first calculate average and standard deviation of the past */ + for (i = 0; i < INTERVALS; i++) + avg += data->intervals[i]; + avg = avg / INTERVALS; + + /* if the avg is beyond the known next tick, it's worthless */ + if (avg > data->expected_us) + return; + + for (i = 0; i < INTERVALS; i++) + stddev += (data->intervals[i] - avg) * + (data->intervals[i] - avg); + + stddev = stddev / INTERVALS; + + /* + * now.. if stddev is small.. then assume we have a + * repeating pattern and predict we keep doing this. + */ + + if (avg && stddev < STDDEV_THRESH) + data->predicted_us = avg; +} + /** * menu_select - selects the next idle state to enter * @dev: the CPU @@ -218,6 +269,8 @@ static int menu_select(struct cpuidle_device *dev) data->predicted_us = div_round64(data->expected_us * data->correction_factor[data->bucket], RESOLUTION * DECAY); + detect_repeating_patterns(data); + /* * We want to default to C1 (hlt), not to busy polling * unless the timer is happening really really soon. @@ -310,6 +363,11 @@ static void menu_update(struct cpuidle_device *dev) new_factor = 1; data->correction_factor[data->bucket] = new_factor; + + /* update the repeating-pattern data */ + data->intervals[data->interval_ptr++] = last_idle_us; + if (data->interval_ptr >= INTERVALS) + data->interval_ptr = 0; } /** diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c index 0ba9c8b..0310ffa 100644 --- a/drivers/cpuidle/sysfs.c +++ b/drivers/cpuidle/sysfs.c @@ -47,10 +47,11 @@ static ssize_t show_current_driver(struct sysdev_class *class, char *buf) { ssize_t ret; + struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); spin_lock(&cpuidle_driver_lock); - if (cpuidle_curr_driver) - ret = sprintf(buf, "%s\n", cpuidle_curr_driver->name); + if (cpuidle_driver) + ret = sprintf(buf, "%s\n", cpuidle_driver->name); else ret = sprintf(buf, "none\n"); spin_unlock(&cpuidle_driver_lock); |