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>

1 files changed, 48 insertions, 10 deletions

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 93bb56d14cfa..13ceb3c69b64 100644
--- 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,