*/
#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
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,
};
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)
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;
}
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)
{
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)
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,
&sampling_rate.attr,
&sampling_down_factor.attr,
&up_threshold.attr,
- &down_threshold.attr,
&ignore_nice.attr,
- &freq_step.attr,
NULL
};
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;
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 */
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)
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();
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / commitdiff