[CPUFREQ] ondemand governor automatic downscaling
[PATCH] [4/5] ondemand governor automatic downscaling Here is a change of policy for the ondemand governor. The modification concerns the frequency downscaling. Instead of decreasing to a lower frequency when the CPU usage is under 20%, this new policy automatically scales to the optimal frequency. The optimal frequency being the lowest frequency which provides enough power to not trigger the upscaling policy. Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Dave Jones <davej@redhat.com>
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@ -34,13 +34,9 @@
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*/
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#define DEF_FREQUENCY_UP_THRESHOLD (80)
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#define MIN_FREQUENCY_UP_THRESHOLD (0)
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#define MIN_FREQUENCY_UP_THRESHOLD (11)
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#define MAX_FREQUENCY_UP_THRESHOLD (100)
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#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
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#define MIN_FREQUENCY_DOWN_THRESHOLD (0)
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#define MAX_FREQUENCY_DOWN_THRESHOLD (100)
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/*
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* The polling frequency of this governor depends on the capability of
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* the processor. Default polling frequency is 1000 times the transition
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@ -77,14 +73,11 @@ struct dbs_tuners {
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unsigned int sampling_rate;
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unsigned int sampling_down_factor;
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unsigned int up_threshold;
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unsigned int down_threshold;
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unsigned int ignore_nice;
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unsigned int freq_step;
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};
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static struct dbs_tuners dbs_tuners_ins = {
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.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
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.down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
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.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
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};
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@ -125,9 +118,7 @@ static ssize_t show_##file_name \
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show_one(sampling_rate, sampling_rate);
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show_one(sampling_down_factor, sampling_down_factor);
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show_one(up_threshold, up_threshold);
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show_one(down_threshold, down_threshold);
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show_one(ignore_nice, ignore_nice);
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show_one(freq_step, freq_step);
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static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
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const char *buf, size_t count)
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@ -173,8 +164,7 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused,
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down(&dbs_sem);
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if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
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input < MIN_FREQUENCY_UP_THRESHOLD ||
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input <= dbs_tuners_ins.down_threshold) {
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input < MIN_FREQUENCY_UP_THRESHOLD) {
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up(&dbs_sem);
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return -EINVAL;
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}
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@ -185,27 +175,6 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused,
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return count;
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}
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static ssize_t store_down_threshold(struct cpufreq_policy *unused,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf (buf, "%u", &input);
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down(&dbs_sem);
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if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD ||
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input < MIN_FREQUENCY_DOWN_THRESHOLD ||
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input >= dbs_tuners_ins.up_threshold) {
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up(&dbs_sem);
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return -EINVAL;
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}
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dbs_tuners_ins.down_threshold = input;
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up(&dbs_sem);
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return count;
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}
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static ssize_t store_ignore_nice(struct cpufreq_policy *policy,
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const char *buf, size_t count)
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{
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@ -240,29 +209,6 @@ static ssize_t store_ignore_nice(struct cpufreq_policy *policy,
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return count;
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}
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static ssize_t store_freq_step(struct cpufreq_policy *policy,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf (buf, "%u", &input);
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if ( ret != 1 )
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return -EINVAL;
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if ( input > 100 )
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input = 100;
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/* no need to test here if freq_step is zero as the user might actually
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* want this, they would be crazy though :) */
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down(&dbs_sem);
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dbs_tuners_ins.freq_step = input;
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up(&dbs_sem);
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return count;
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}
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#define define_one_rw(_name) \
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static struct freq_attr _name = \
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__ATTR(_name, 0644, show_##_name, store_##_name)
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@ -270,9 +216,7 @@ __ATTR(_name, 0644, show_##_name, store_##_name)
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define_one_rw(sampling_rate);
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define_one_rw(sampling_down_factor);
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define_one_rw(up_threshold);
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define_one_rw(down_threshold);
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define_one_rw(ignore_nice);
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define_one_rw(freq_step);
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static struct attribute * dbs_attributes[] = {
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&sampling_rate_max.attr,
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@ -280,9 +224,7 @@ static struct attribute * dbs_attributes[] = {
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&sampling_rate.attr,
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&sampling_down_factor.attr,
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&up_threshold.attr,
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&down_threshold.attr,
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&ignore_nice.attr,
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&freq_step.attr,
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NULL
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};
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@ -295,8 +237,8 @@ static struct attribute_group dbs_attr_group = {
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static void dbs_check_cpu(int cpu)
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{
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unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
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unsigned int freq_down_step;
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unsigned int idle_ticks, up_idle_ticks, total_ticks;
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unsigned int freq_next;
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unsigned int freq_down_sampling_rate;
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static int down_skip[NR_CPUS];
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struct cpu_dbs_info_s *this_dbs_info;
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@ -310,17 +252,15 @@ static void dbs_check_cpu(int cpu)
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policy = this_dbs_info->cur_policy;
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/*
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* The default safe range is 20% to 80%
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* Every sampling_rate, we check
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* - If current idle time is less than 20%, then we try to
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* increase frequency
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* Every sampling_rate*sampling_down_factor, we check
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* - If current idle time is more than 80%, then we try to
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* decrease frequency
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* Every sampling_rate, we check, if current idle time is less
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* than 20% (default), then we try to increase frequency
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* Every sampling_rate*sampling_down_factor, we look for a the lowest
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* frequency which can sustain the load while keeping idle time over
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* 30%. If such a frequency exist, we try to decrease to this frequency.
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*
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* Any frequency increase takes it to the maximum frequency.
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* Frequency reduction happens at minimum steps of
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* 5% (default) of max_frequency
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* 5% (default) of current frequency
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*/
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/* Check for frequency increase */
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@ -383,33 +323,27 @@ static void dbs_check_cpu(int cpu)
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idle_ticks = tmp_idle_ticks;
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}
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/* Scale idle ticks by 100 and compare with up and down ticks */
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idle_ticks *= 100;
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down_skip[cpu] = 0;
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/* if we cannot reduce the frequency anymore, break out early */
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if (policy->cur == policy->min)
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return;
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/* Compute how many ticks there are between two measurements */
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freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
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dbs_tuners_ins.sampling_down_factor;
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down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
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usecs_to_jiffies(freq_down_sampling_rate);
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total_ticks = usecs_to_jiffies(freq_down_sampling_rate);
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if (idle_ticks > down_idle_ticks) {
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/* if we are already at the lowest speed then break out early
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* or if we 'cannot' reduce the speed as the user might want
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* freq_step to be zero */
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if (policy->cur == policy->min || dbs_tuners_ins.freq_step == 0)
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return;
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/*
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* The optimal frequency is the frequency that is the lowest that
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* can support the current CPU usage without triggering the up
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* policy. To be safe, we focus 10 points under the threshold.
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*/
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freq_next = ((total_ticks - idle_ticks) * 100) / total_ticks;
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freq_next = (freq_next * policy->cur) /
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(dbs_tuners_ins.up_threshold - 10);
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freq_down_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
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/* max freq cannot be less than 100. But who knows.... */
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if (unlikely(freq_down_step == 0))
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freq_down_step = 5;
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__cpufreq_driver_target(policy,
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policy->cur - freq_down_step,
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CPUFREQ_RELATION_H);
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return;
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}
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if (freq_next <= ((policy->cur * 95) / 100))
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__cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L);
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}
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static void do_dbs_timer(void *data)
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DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
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dbs_tuners_ins.sampling_rate = def_sampling_rate;
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dbs_tuners_ins.ignore_nice = 0;
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dbs_tuners_ins.freq_step = 5;
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dbs_timer_init();
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}
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