diff options
Diffstat (limited to 'drivers/cpufreq/cpufreq_conservative.c')
| -rw-r--r-- | drivers/cpufreq/cpufreq_conservative.c | 104 |
1 files changed, 38 insertions, 66 deletions
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c index 7a74d175287b..bdea7e2f94ba 100644 --- a/drivers/cpufreq/cpufreq_conservative.c +++ b/drivers/cpufreq/cpufreq_conservative.c @@ -42,27 +42,12 @@ * this governor will not work. * All times here are in uS. */ -static unsigned int def_sampling_rate; #define MIN_SAMPLING_RATE_RATIO (2) -/* for correct statistics, we need at least 10 ticks between each measure */ -#define MIN_STAT_SAMPLING_RATE \ - (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10)) -#define MIN_SAMPLING_RATE \ - (def_sampling_rate / MIN_SAMPLING_RATE_RATIO) -/* Above MIN_SAMPLING_RATE will vanish with its sysfs file soon - * Define the minimal settable sampling rate to the greater of: - * - "HW transition latency" * 100 (same as default sampling / 10) - * - MIN_STAT_SAMPLING_RATE - * To avoid that userspace shoots itself. -*/ -static unsigned int minimum_sampling_rate(void) -{ - return max(def_sampling_rate / 10, MIN_STAT_SAMPLING_RATE); -} -/* This will also vanish soon with removing sampling_rate_max */ -#define MAX_SAMPLING_RATE (500 * def_sampling_rate) +static unsigned int min_sampling_rate; + #define LATENCY_MULTIPLIER (1000) +#define MIN_LATENCY_MULTIPLIER (100) #define DEF_SAMPLING_DOWN_FACTOR (1) #define MAX_SAMPLING_DOWN_FACTOR (10) #define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000) @@ -79,21 +64,20 @@ struct cpu_dbs_info_s { unsigned int requested_freq; int cpu; unsigned int enable:1; + /* + * percpu mutex that serializes governor limit change with + * do_dbs_timer invocation. We do not want do_dbs_timer to run + * when user is changing the governor or limits. + */ + struct mutex timer_mutex; }; static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info); static unsigned int dbs_enable; /* number of CPUs using this policy */ /* - * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug - * lock and dbs_mutex. cpu_hotplug lock should always be held before - * dbs_mutex. If any function that can potentially take cpu_hotplug lock - * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then - * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock - * is recursive for the same process. -Venki - * DEADLOCK ALERT! (2) : do_dbs_timer() must not take the dbs_mutex, because it - * would deadlock with cancel_delayed_work_sync(), which is needed for proper - * raceless workqueue teardown. + * dbs_mutex protects data in dbs_tuners_ins from concurrent changes on + * different CPUs. It protects dbs_enable in governor start/stop. */ static DEFINE_MUTEX(dbs_mutex); @@ -182,27 +166,14 @@ static struct notifier_block dbs_cpufreq_notifier_block = { /************************** sysfs interface ************************/ static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf) { - static int print_once; - - if (!print_once) { - printk(KERN_INFO "CPUFREQ: conservative sampling_rate_max " - "sysfs file is deprecated - used by: %s\n", - current->comm); - print_once = 1; - } - return sprintf(buf, "%u\n", MAX_SAMPLING_RATE); + printk_once(KERN_INFO "CPUFREQ: conservative sampling_rate_max " + "sysfs file is deprecated - used by: %s\n", current->comm); + return sprintf(buf, "%u\n", -1U); } static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf) { - static int print_once; - - if (!print_once) { - printk(KERN_INFO "CPUFREQ: conservative sampling_rate_max " - "sysfs file is deprecated - used by: %s\n", current->comm); - print_once = 1; - } - return sprintf(buf, "%u\n", MIN_SAMPLING_RATE); + return sprintf(buf, "%u\n", min_sampling_rate); } #define define_one_ro(_name) \ @@ -254,7 +225,7 @@ static ssize_t store_sampling_rate(struct cpufreq_policy *unused, return -EINVAL; mutex_lock(&dbs_mutex); - dbs_tuners_ins.sampling_rate = max(input, minimum_sampling_rate()); + dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate); mutex_unlock(&dbs_mutex); return count; @@ -516,18 +487,12 @@ static void do_dbs_timer(struct work_struct *work) delay -= jiffies % delay; - if (lock_policy_rwsem_write(cpu) < 0) - return; - - if (!dbs_info->enable) { - unlock_policy_rwsem_write(cpu); - return; - } + mutex_lock(&dbs_info->timer_mutex); dbs_check_cpu(dbs_info); queue_delayed_work_on(cpu, kconservative_wq, &dbs_info->work, delay); - unlock_policy_rwsem_write(cpu); + mutex_unlock(&dbs_info->timer_mutex); } static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info) @@ -563,9 +528,6 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, if ((!cpu_online(cpu)) || (!policy->cur)) return -EINVAL; - if (this_dbs_info->enable) /* Already enabled */ - break; - mutex_lock(&dbs_mutex); rc = sysfs_create_group(&policy->kobj, &dbs_attr_group); @@ -589,6 +551,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, this_dbs_info->down_skip = 0; this_dbs_info->requested_freq = policy->cur; + mutex_init(&this_dbs_info->timer_mutex); dbs_enable++; /* * Start the timerschedule work, when this governor @@ -601,27 +564,36 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, if (latency == 0) latency = 1; - def_sampling_rate = - max(latency * LATENCY_MULTIPLIER, - MIN_STAT_SAMPLING_RATE); - - dbs_tuners_ins.sampling_rate = def_sampling_rate; + /* + * conservative does not implement micro like ondemand + * governor, thus we are bound to jiffes/HZ + */ + min_sampling_rate = + MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10); + /* Bring kernel and HW constraints together */ + min_sampling_rate = max(min_sampling_rate, + MIN_LATENCY_MULTIPLIER * latency); + dbs_tuners_ins.sampling_rate = + max(min_sampling_rate, + latency * LATENCY_MULTIPLIER); cpufreq_register_notifier( &dbs_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER); } - dbs_timer_init(this_dbs_info); - mutex_unlock(&dbs_mutex); + dbs_timer_init(this_dbs_info); + break; case CPUFREQ_GOV_STOP: - mutex_lock(&dbs_mutex); dbs_timer_exit(this_dbs_info); + + mutex_lock(&dbs_mutex); sysfs_remove_group(&policy->kobj, &dbs_attr_group); dbs_enable--; + mutex_destroy(&this_dbs_info->timer_mutex); /* * Stop the timerschedule work, when this governor @@ -637,7 +609,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, break; case CPUFREQ_GOV_LIMITS: - mutex_lock(&dbs_mutex); + mutex_lock(&this_dbs_info->timer_mutex); if (policy->max < this_dbs_info->cur_policy->cur) __cpufreq_driver_target( this_dbs_info->cur_policy, @@ -646,7 +618,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, __cpufreq_driver_target( this_dbs_info->cur_policy, policy->min, CPUFREQ_RELATION_L); - mutex_unlock(&dbs_mutex); + mutex_unlock(&this_dbs_info->timer_mutex); break; } |