diff options
| -rw-r--r-- | drivers/cpufreq/cpufreq_ondemand.c | 117 |
1 files changed, 25 insertions, 92 deletions
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index 0482bd49aba8..8bc38ab96400 100644 --- a/drivers/cpufreq/cpufreq_ondemand.c +++ b/drivers/cpufreq/cpufreq_ondemand.c @@ -34,13 +34,9 @@ */ #define DEF_FREQUENCY_UP_THRESHOLD (80) -#define MIN_FREQUENCY_UP_THRESHOLD (0) +#define MIN_FREQUENCY_UP_THRESHOLD (11) #define MAX_FREQUENCY_UP_THRESHOLD (100) -#define DEF_FREQUENCY_DOWN_THRESHOLD (20) -#define MIN_FREQUENCY_DOWN_THRESHOLD (0) -#define MAX_FREQUENCY_DOWN_THRESHOLD (100) - /* * The polling frequency of this governor depends on the capability of * the processor. Default polling frequency is 1000 times the transition @@ -77,14 +73,11 @@ struct dbs_tuners { unsigned int sampling_rate; unsigned int sampling_down_factor; unsigned int up_threshold; - unsigned int down_threshold; unsigned int ignore_nice; - unsigned int freq_step; }; static struct dbs_tuners dbs_tuners_ins = { .up_threshold = DEF_FREQUENCY_UP_THRESHOLD, - .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD, .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR, }; @@ -125,9 +118,7 @@ static ssize_t show_##file_name \ show_one(sampling_rate, sampling_rate); show_one(sampling_down_factor, sampling_down_factor); show_one(up_threshold, up_threshold); -show_one(down_threshold, down_threshold); show_one(ignore_nice, ignore_nice); -show_one(freq_step, freq_step); static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused, const char *buf, size_t count) @@ -173,8 +164,7 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused, down(&dbs_sem); if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || - input < MIN_FREQUENCY_UP_THRESHOLD || - input <= dbs_tuners_ins.down_threshold) { + input < MIN_FREQUENCY_UP_THRESHOLD) { up(&dbs_sem); return -EINVAL; } @@ -185,27 +175,6 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused, return count; } -static ssize_t store_down_threshold(struct cpufreq_policy *unused, - const char *buf, size_t count) -{ - unsigned int input; - int ret; - ret = sscanf (buf, "%u", &input); - - down(&dbs_sem); - if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD || - input < MIN_FREQUENCY_DOWN_THRESHOLD || - input >= dbs_tuners_ins.up_threshold) { - up(&dbs_sem); - return -EINVAL; - } - - dbs_tuners_ins.down_threshold = input; - up(&dbs_sem); - - return count; -} - static ssize_t store_ignore_nice(struct cpufreq_policy *policy, const char *buf, size_t count) { @@ -240,29 +209,6 @@ static ssize_t store_ignore_nice(struct cpufreq_policy *policy, return count; } -static ssize_t store_freq_step(struct cpufreq_policy *policy, - const char *buf, size_t count) -{ - unsigned int input; - int ret; - - ret = sscanf (buf, "%u", &input); - - if ( ret != 1 ) - return -EINVAL; - - if ( input > 100 ) - input = 100; - - /* no need to test here if freq_step is zero as the user might actually - * want this, they would be crazy though :) */ - down(&dbs_sem); - dbs_tuners_ins.freq_step = input; - up(&dbs_sem); - - return count; -} - #define define_one_rw(_name) \ static struct freq_attr _name = \ __ATTR(_name, 0644, show_##_name, store_##_name) @@ -270,9 +216,7 @@ __ATTR(_name, 0644, show_##_name, store_##_name) define_one_rw(sampling_rate); define_one_rw(sampling_down_factor); define_one_rw(up_threshold); -define_one_rw(down_threshold); define_one_rw(ignore_nice); -define_one_rw(freq_step); static struct attribute * dbs_attributes[] = { &sampling_rate_max.attr, @@ -280,9 +224,7 @@ static struct attribute * dbs_attributes[] = { &sampling_rate.attr, &sampling_down_factor.attr, &up_threshold.attr, - &down_threshold.attr, &ignore_nice.attr, - &freq_step.attr, NULL }; @@ -295,8 +237,8 @@ static struct attribute_group dbs_attr_group = { static void dbs_check_cpu(int cpu) { - unsigned int idle_ticks, up_idle_ticks, down_idle_ticks; - unsigned int freq_down_step; + unsigned int idle_ticks, up_idle_ticks, total_ticks; + unsigned int freq_next; unsigned int freq_down_sampling_rate; static int down_skip[NR_CPUS]; struct cpu_dbs_info_s *this_dbs_info; @@ -310,17 +252,15 @@ static void dbs_check_cpu(int cpu) policy = this_dbs_info->cur_policy; /* - * The default safe range is 20% to 80% - * Every sampling_rate, we check - * - If current idle time is less than 20%, then we try to - * increase frequency - * Every sampling_rate*sampling_down_factor, we check - * - If current idle time is more than 80%, then we try to - * decrease frequency + * Every sampling_rate, we check, if current idle time is less + * than 20% (default), then we try to increase frequency + * Every sampling_rate*sampling_down_factor, we look for a the lowest + * frequency which can sustain the load while keeping idle time over + * 30%. If such a frequency exist, we try to decrease to this frequency. * * Any frequency increase takes it to the maximum frequency. * Frequency reduction happens at minimum steps of - * 5% (default) of max_frequency + * 5% (default) of current frequency */ /* Check for frequency increase */ @@ -383,33 +323,27 @@ static void dbs_check_cpu(int cpu) idle_ticks = tmp_idle_ticks; } - /* Scale idle ticks by 100 and compare with up and down ticks */ - idle_ticks *= 100; down_skip[cpu] = 0; + /* if we cannot reduce the frequency anymore, break out early */ + if (policy->cur == policy->min) + return; + /* Compute how many ticks there are between two measurements */ freq_down_sampling_rate = dbs_tuners_ins.sampling_rate * dbs_tuners_ins.sampling_down_factor; - down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) * - usecs_to_jiffies(freq_down_sampling_rate); - - if (idle_ticks > down_idle_ticks) { - /* if we are already at the lowest speed then break out early - * or if we 'cannot' reduce the speed as the user might want - * freq_step to be zero */ - if (policy->cur == policy->min || dbs_tuners_ins.freq_step == 0) - return; + total_ticks = usecs_to_jiffies(freq_down_sampling_rate); - freq_down_step = (dbs_tuners_ins.freq_step * policy->max) / 100; - - /* max freq cannot be less than 100. But who knows.... */ - if (unlikely(freq_down_step == 0)) - freq_down_step = 5; + /* + * The optimal frequency is the frequency that is the lowest that + * can support the current CPU usage without triggering the up + * policy. To be safe, we focus 10 points under the threshold. + */ + freq_next = ((total_ticks - idle_ticks) * 100) / total_ticks; + freq_next = (freq_next * policy->cur) / + (dbs_tuners_ins.up_threshold - 10); - __cpufreq_driver_target(policy, - policy->cur - freq_down_step, - CPUFREQ_RELATION_H); - return; - } + if (freq_next <= ((policy->cur * 95) / 100)) + __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L); } static void do_dbs_timer(void *data) @@ -487,7 +421,6 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, DEF_SAMPLING_RATE_LATENCY_MULTIPLIER; dbs_tuners_ins.sampling_rate = def_sampling_rate; dbs_tuners_ins.ignore_nice = 0; - dbs_tuners_ins.freq_step = 5; dbs_timer_init(); } |