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[CPUFREQ] Remove slowdown from ondemand sampling path.
Remove slowdown from ondemand sampling path. This reduces the code path length in dbs_check_cpu() by half. slowdown was not used by ondemand by default. If there are any user level tools that were using this tunable, they may report error now. Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Dave Jones <davej@redhat.com>
This commit is contained in:
Venkatesh Pallipadi
Dave Jones
parent
501b7c77de
commit
ccb2fe209d
2 changed files with 42 additions and 98 deletions
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@ -56,16 +56,14 @@ static unsigned int def_sampling_rate;
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#define MIN_SAMPLING_RATE (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
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#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
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#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (1000)
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#define DEF_SAMPLING_DOWN_FACTOR (1)
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#define MAX_SAMPLING_DOWN_FACTOR (10)
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#define TRANSITION_LATENCY_LIMIT (10 * 1000)
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static void do_dbs_timer(void *data);
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struct cpu_dbs_info_s {
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cputime64_t prev_cpu_idle;
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cputime64_t prev_cpu_wall;
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struct cpufreq_policy *cur_policy;
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unsigned int prev_cpu_idle_up;
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unsigned int prev_cpu_idle_down;
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unsigned int enable;
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};
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static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
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@ -87,24 +85,26 @@ static struct workqueue_struct *dbs_workq;
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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 ignore_nice;
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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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.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
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.ignore_nice = 0,
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};
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static inline unsigned int get_cpu_idle_time(unsigned int cpu)
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static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
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{
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return kstat_cpu(cpu).cpustat.idle +
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kstat_cpu(cpu).cpustat.iowait +
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( dbs_tuners_ins.ignore_nice ?
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kstat_cpu(cpu).cpustat.nice :
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0);
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cputime64_t retval;
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retval = cputime64_add(kstat_cpu(cpu).cpustat.idle,
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kstat_cpu(cpu).cpustat.iowait);
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if (dbs_tuners_ins.ignore_nice)
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retval = cputime64_add(retval, kstat_cpu(cpu).cpustat.nice);
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return retval;
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}
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/************************** sysfs interface ************************/
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@ -133,29 +133,9 @@ static ssize_t show_##file_name \
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return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
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}
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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(ignore_nice_load, ignore_nice);
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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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{
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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 > MAX_SAMPLING_DOWN_FACTOR || input < 1)
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return -EINVAL;
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mutex_lock(&dbs_mutex);
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dbs_tuners_ins.sampling_down_factor = input;
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mutex_unlock(&dbs_mutex);
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return count;
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}
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static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
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const char *buf, size_t count)
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{
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@ -217,12 +197,12 @@ static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
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}
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dbs_tuners_ins.ignore_nice = input;
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/* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
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/* we need to re-evaluate prev_cpu_idle */
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for_each_online_cpu(j) {
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struct cpu_dbs_info_s *j_dbs_info;
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j_dbs_info = &per_cpu(cpu_dbs_info, j);
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j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
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j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
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struct cpu_dbs_info_s *dbs_info;
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dbs_info = &per_cpu(cpu_dbs_info, j);
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dbs_info->prev_cpu_idle = get_cpu_idle_time(j);
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dbs_info->prev_cpu_wall = get_jiffies_64();
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}
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mutex_unlock(&dbs_mutex);
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@ -234,7 +214,6 @@ static struct freq_attr _name = \
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__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(ignore_nice_load);
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@ -242,7 +221,6 @@ static struct attribute * dbs_attributes[] = {
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&sampling_rate_max.attr,
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&sampling_rate_min.attr,
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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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&ignore_nice_load.attr,
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NULL
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@ -257,11 +235,10 @@ 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, 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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unsigned int idle_ticks, total_ticks;
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unsigned int load;
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struct cpu_dbs_info_s *this_dbs_info;
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cputime64_t cur_jiffies;
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struct cpufreq_policy *policy;
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unsigned int j;
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@ -271,10 +248,14 @@ static void dbs_check_cpu(int cpu)
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return;
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policy = this_dbs_info->cur_policy;
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cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
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total_ticks = (unsigned int) cputime64_sub(cur_jiffies,
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this_dbs_info->prev_cpu_wall);
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this_dbs_info->prev_cpu_wall = cur_jiffies;
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/*
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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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* Every sampling_rate, 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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@ -283,36 +264,26 @@ static void dbs_check_cpu(int cpu)
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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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/* Get Idle Time */
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idle_ticks = UINT_MAX;
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for_each_cpu_mask(j, policy->cpus) {
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unsigned int tmp_idle_ticks, total_idle_ticks;
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cputime64_t total_idle_ticks;
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unsigned int tmp_idle_ticks;
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struct cpu_dbs_info_s *j_dbs_info;
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j_dbs_info = &per_cpu(cpu_dbs_info, j);
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total_idle_ticks = get_cpu_idle_time(j);
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tmp_idle_ticks = total_idle_ticks -
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j_dbs_info->prev_cpu_idle_up;
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j_dbs_info->prev_cpu_idle_up = total_idle_ticks;
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tmp_idle_ticks = (unsigned int) cputime64_sub(total_idle_ticks,
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j_dbs_info->prev_cpu_idle);
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j_dbs_info->prev_cpu_idle = total_idle_ticks;
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if (tmp_idle_ticks < idle_ticks)
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idle_ticks = tmp_idle_ticks;
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}
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load = (100 * (total_ticks - idle_ticks)) / total_ticks;
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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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up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
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usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
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if (idle_ticks < up_idle_ticks) {
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down_skip[cpu] = 0;
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for_each_cpu_mask(j, policy->cpus) {
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struct cpu_dbs_info_s *j_dbs_info;
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j_dbs_info = &per_cpu(cpu_dbs_info, j);
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j_dbs_info->prev_cpu_idle_down =
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j_dbs_info->prev_cpu_idle_up;
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}
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/* Check for frequency increase */
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if (load > dbs_tuners_ins.up_threshold) {
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/* if we are already at full speed then break out early */
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if (policy->cur == policy->max)
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return;
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@ -323,50 +294,22 @@ static void dbs_check_cpu(int cpu)
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}
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/* Check for frequency decrease */
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down_skip[cpu]++;
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if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
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return;
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idle_ticks = UINT_MAX;
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for_each_cpu_mask(j, policy->cpus) {
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unsigned int tmp_idle_ticks, total_idle_ticks;
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struct cpu_dbs_info_s *j_dbs_info;
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j_dbs_info = &per_cpu(cpu_dbs_info, j);
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/* Check for frequency decrease */
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total_idle_ticks = j_dbs_info->prev_cpu_idle_up;
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tmp_idle_ticks = total_idle_ticks -
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j_dbs_info->prev_cpu_idle_down;
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j_dbs_info->prev_cpu_idle_down = total_idle_ticks;
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if (tmp_idle_ticks < idle_ticks)
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idle_ticks = tmp_idle_ticks;
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}
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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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total_ticks = usecs_to_jiffies(freq_down_sampling_rate);
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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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if (load < (dbs_tuners_ins.up_threshold - 10)) {
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unsigned int freq_next;
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freq_next = (policy->cur * load) /
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(dbs_tuners_ins.up_threshold - 10);
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if (freq_next < policy->min)
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freq_next = policy->min;
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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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}
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static void do_dbs_timer(void *data)
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@ -432,9 +375,8 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
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j_dbs_info = &per_cpu(cpu_dbs_info, j);
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j_dbs_info->cur_policy = policy;
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j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
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j_dbs_info->prev_cpu_idle_down
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= j_dbs_info->prev_cpu_idle_up;
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j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j);
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j_dbs_info->prev_cpu_wall = get_jiffies_64();
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}
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this_dbs_info->enable = 1;
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sysfs_create_group(&policy->kobj, &dbs_attr_group);
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@ -24,7 +24,9 @@ typedef u64 cputime64_t;
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#define cputime64_zero (0ULL)
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#define cputime64_add(__a, __b) ((__a) + (__b))
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#define cputime64_sub(__a, __b) ((__a) - (__b))
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#define cputime64_to_jiffies64(__ct) (__ct)
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#define jiffies64_to_cputime64(__jif) (__jif)
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#define cputime_to_cputime64(__ct) ((u64) __ct)
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