cpufreq: governors: Calculate iowait time only when necessary
Currently we always calculate the CPU iowait time and add it to idle time. If we are in ondemand and we use io_is_busy, we re-calculate iowait time and we subtract it from idle time. With this patch iowait time is calculated only when necessary avoiding the double call to get_cpu_iowait_time_us. We use a parameter in function get_cpu_idle_time to distinguish when the iowait time will be added to idle time or not, without the need of keeping the prev_io_wait. Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr> Acked-by: Viresh Kumar <viresh.kumar@linaro.,org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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@ -240,7 +240,7 @@ static ssize_t store_ignore_nice(struct dbs_data *dbs_data, const char *buf,
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struct cs_cpu_dbs_info_s *dbs_info;
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dbs_info = &per_cpu(cs_cpu_dbs_info, j);
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dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
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&dbs_info->cdbs.prev_cpu_wall);
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&dbs_info->cdbs.prev_cpu_wall, 0);
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if (cs_tuners->ignore_nice)
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dbs_info->cdbs.prev_cpu_nice =
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kcpustat_cpu(j).cpustat[CPUTIME_NICE];
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@ -67,13 +67,13 @@ static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
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return cputime_to_usecs(idle_time);
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}
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u64 get_cpu_idle_time(unsigned int cpu, u64 *wall)
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u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy)
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{
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u64 idle_time = get_cpu_idle_time_us(cpu, NULL);
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u64 idle_time = get_cpu_idle_time_us(cpu, io_busy ? wall : NULL);
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if (idle_time == -1ULL)
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return get_cpu_idle_time_jiffy(cpu, wall);
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else
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else if (!io_busy)
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idle_time += get_cpu_iowait_time_us(cpu, wall);
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return idle_time;
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@ -100,13 +100,22 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
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/* Get Absolute Load (in terms of freq for ondemand gov) */
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for_each_cpu(j, policy->cpus) {
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struct cpu_dbs_common_info *j_cdbs;
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u64 cur_wall_time, cur_idle_time, cur_iowait_time;
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unsigned int idle_time, wall_time, iowait_time;
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u64 cur_wall_time, cur_idle_time;
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unsigned int idle_time, wall_time;
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unsigned int load;
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int io_busy = 0;
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j_cdbs = dbs_data->cdata->get_cpu_cdbs(j);
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cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
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/*
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* For the purpose of ondemand, waiting for disk IO is
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* an indication that you're performance critical, and
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* not that the system is actually idle. So do not add
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* the iowait time to the cpu idle time.
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*/
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if (dbs_data->cdata->governor == GOV_ONDEMAND)
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io_busy = od_tuners->io_is_busy;
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cur_idle_time = get_cpu_idle_time(j, &cur_wall_time, io_busy);
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wall_time = (unsigned int)
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(cur_wall_time - j_cdbs->prev_cpu_wall);
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@ -134,29 +143,6 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
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idle_time += jiffies_to_usecs(cur_nice_jiffies);
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}
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if (dbs_data->cdata->governor == GOV_ONDEMAND) {
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struct od_cpu_dbs_info_s *od_j_dbs_info =
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dbs_data->cdata->get_cpu_dbs_info_s(cpu);
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cur_iowait_time = get_cpu_iowait_time_us(j,
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&cur_wall_time);
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if (cur_iowait_time == -1ULL)
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cur_iowait_time = 0;
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iowait_time = (unsigned int) (cur_iowait_time -
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od_j_dbs_info->prev_cpu_iowait);
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od_j_dbs_info->prev_cpu_iowait = cur_iowait_time;
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/*
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* For the purpose of ondemand, waiting for disk IO is
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* an indication that you're performance critical, and
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* not that the system is actually idle. So subtract the
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* iowait time from the cpu idle time.
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*/
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if (od_tuners->io_is_busy && idle_time >= iowait_time)
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idle_time -= iowait_time;
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}
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if (unlikely(!wall_time || wall_time < idle_time))
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continue;
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@ -254,6 +240,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
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struct cs_dbs_tuners *cs_tuners = NULL;
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struct cpu_dbs_common_info *cpu_cdbs;
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unsigned int sampling_rate, latency, ignore_nice, j, cpu = policy->cpu;
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int io_busy = 0;
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int rc;
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if (have_governor_per_policy())
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@ -353,6 +340,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
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sampling_rate = od_tuners->sampling_rate;
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ignore_nice = od_tuners->ignore_nice;
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od_ops = dbs_data->cdata->gov_ops;
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io_busy = od_tuners->io_is_busy;
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}
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switch (event) {
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@ -369,7 +357,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
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j_cdbs->cpu = j;
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j_cdbs->cur_policy = policy;
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j_cdbs->prev_cpu_idle = get_cpu_idle_time(j,
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&j_cdbs->prev_cpu_wall);
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&j_cdbs->prev_cpu_wall, io_busy);
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if (ignore_nice)
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j_cdbs->prev_cpu_nice =
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kcpustat_cpu(j).cpustat[CPUTIME_NICE];
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@ -148,7 +148,6 @@ struct cpu_dbs_common_info {
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struct od_cpu_dbs_info_s {
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struct cpu_dbs_common_info cdbs;
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u64 prev_cpu_iowait;
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struct cpufreq_frequency_table *freq_table;
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unsigned int freq_lo;
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unsigned int freq_lo_jiffies;
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@ -256,7 +255,7 @@ static ssize_t show_sampling_rate_min_gov_pol \
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return sprintf(buf, "%u\n", dbs_data->min_sampling_rate); \
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}
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u64 get_cpu_idle_time(unsigned int cpu, u64 *wall);
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u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy);
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void dbs_check_cpu(struct dbs_data *dbs_data, int cpu);
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bool need_load_eval(struct cpu_dbs_common_info *cdbs,
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unsigned int sampling_rate);
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@ -339,11 +339,20 @@ static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf,
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struct od_dbs_tuners *od_tuners = dbs_data->tuners;
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unsigned int input;
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int ret;
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unsigned int j;
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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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od_tuners->io_is_busy = !!input;
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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 od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
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j);
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dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
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&dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
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}
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return count;
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}
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@ -414,7 +423,7 @@ static ssize_t store_ignore_nice(struct dbs_data *dbs_data, const char *buf,
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struct od_cpu_dbs_info_s *dbs_info;
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dbs_info = &per_cpu(od_cpu_dbs_info, j);
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dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
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&dbs_info->cdbs.prev_cpu_wall);
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&dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy);
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if (od_tuners->ignore_nice)
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dbs_info->cdbs.prev_cpu_nice =
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kcpustat_cpu(j).cpustat[CPUTIME_NICE];
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