cpufreq: ondemand: call dbs_check_cpu only when necessary

Modify ondemand timer to not resample CPU utilization if recently
sampled from another SW coordinated core.

Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index b0e4506..ee8b7ca 100644 (file)
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -290,6 +290,9 @@ second_time:
                mutex_unlock(&dbs_data->mutex);
 
                if (dbs_sw_coordinated_cpus(cpu_cdbs)) {
+                       /* Initiate timer time stamp */
+                       cpu_cdbs->time_stamp = ktime_get();
+
                        for_each_cpu(j, policy->cpus) {
                                struct cpu_dbs_common_info *j_cdbs;
 

diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
index 5bf6fb8..aaf073d 100644 (file)
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -82,6 +82,7 @@ struct cpu_dbs_common_info {
         * the governor or limits.
         */
        struct mutex timer_mutex;
+       ktime_t time_stamp;
 };
 
 struct od_cpu_dbs_info_s {

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 93bb56d..13ceb3c 100644 (file)
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -216,23 +216,23 @@ static void od_check_cpu(int cpu, unsigned int load_freq)
        }
 }
 
-static void od_dbs_timer(struct work_struct *work)
+static void od_timer_update(struct od_cpu_dbs_info_s *dbs_info, bool sample,
+                           struct delayed_work *dw)
 {
-       struct od_cpu_dbs_info_s *dbs_info =
-               container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);
        unsigned int cpu = dbs_info->cdbs.cpu;
        int delay, sample_type = dbs_info->sample_type;
 
-       mutex_lock(&dbs_info->cdbs.timer_mutex);
-
        /* Common NORMAL_SAMPLE setup */
        dbs_info->sample_type = OD_NORMAL_SAMPLE;
        if (sample_type == OD_SUB_SAMPLE) {
                delay = dbs_info->freq_lo_jiffies;
-               __cpufreq_driver_target(dbs_info->cdbs.cur_policy,
-                       dbs_info->freq_lo, CPUFREQ_RELATION_H);
+               if (sample)
+                       __cpufreq_driver_target(dbs_info->cdbs.cur_policy,
+                                               dbs_info->freq_lo,
+                                               CPUFREQ_RELATION_H);
        } else {
-               dbs_check_cpu(&od_dbs_data, cpu);
+               if (sample)
+                       dbs_check_cpu(&od_dbs_data, cpu);
                if (dbs_info->freq_lo) {
                        /* Setup timer for SUB_SAMPLE */
                        dbs_info->sample_type = OD_SUB_SAMPLE;
@@ -243,11 +243,49 @@ static void od_dbs_timer(struct work_struct *work)
                }
        }
 
-       schedule_delayed_work_on(smp_processor_id(), &dbs_info->cdbs.work,
-                       delay);
+       schedule_delayed_work_on(smp_processor_id(), dw, delay);
+}
+
+static void od_timer_coordinated(struct od_cpu_dbs_info_s *dbs_info_local,
+                                struct delayed_work *dw)
+{
+       struct od_cpu_dbs_info_s *dbs_info;
+       ktime_t time_now;
+       s64 delta_us;
+       bool sample = true;
+
+       /* use leader CPU's dbs_info */
+       dbs_info = &per_cpu(od_cpu_dbs_info, dbs_info_local->cdbs.cpu);
+       mutex_lock(&dbs_info->cdbs.timer_mutex);
+
+       time_now = ktime_get();
+       delta_us = ktime_us_delta(time_now, dbs_info->cdbs.time_stamp);
+
+       /* Do nothing if we recently have sampled */
+       if (delta_us < (s64)(od_tuners.sampling_rate / 2))
+               sample = false;
+       else
+               dbs_info->cdbs.time_stamp = time_now;
+
+       od_timer_update(dbs_info, sample, dw);
        mutex_unlock(&dbs_info->cdbs.timer_mutex);
 }
 
+static void od_dbs_timer(struct work_struct *work)
+{
+       struct delayed_work *dw = to_delayed_work(work);
+       struct od_cpu_dbs_info_s *dbs_info =
+               container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);
+
+       if (dbs_sw_coordinated_cpus(&dbs_info->cdbs)) {
+               od_timer_coordinated(dbs_info, dw);
+       } else {
+               mutex_lock(&dbs_info->cdbs.timer_mutex);
+               od_timer_update(dbs_info, true, dw);
+               mutex_unlock(&dbs_info->cdbs.timer_mutex);
+       }
+}
+
 /************************** sysfs interface ************************/
 
 static ssize_t show_sampling_rate_min(struct kobject *kobj,