cpufreq: conservative: call dbs_check_cpu only when necessary

Modify conservative 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_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index b9d7f14..5d8e894 100644 (file)
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -111,22 +111,57 @@ static void cs_check_cpu(int cpu, unsigned int load)
        }
 }
 
-static void cs_dbs_timer(struct work_struct *work)
+static void cs_timer_update(struct cs_cpu_dbs_info_s *dbs_info, bool sample,
+                           struct delayed_work *dw)
 {
-       struct cs_cpu_dbs_info_s *dbs_info = container_of(work,
-                       struct cs_cpu_dbs_info_s, cdbs.work.work);
        unsigned int cpu = dbs_info->cdbs.cpu;
        int delay = delay_for_sampling_rate(cs_tuners.sampling_rate);
 
+       if (sample)
+               dbs_check_cpu(&cs_dbs_data, cpu);
+
+       schedule_delayed_work_on(smp_processor_id(), dw, delay);
+}
+
+static void cs_timer_coordinated(struct cs_cpu_dbs_info_s *dbs_info_local,
+                                struct delayed_work *dw)
+{
+       struct cs_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(cs_cpu_dbs_info, dbs_info_local->cdbs.cpu);
        mutex_lock(&dbs_info->cdbs.timer_mutex);
 
-       dbs_check_cpu(&cs_dbs_data, cpu);
+       time_now = ktime_get();
+       delta_us = ktime_us_delta(time_now, dbs_info->cdbs.time_stamp);
 
-       schedule_delayed_work_on(smp_processor_id(), &dbs_info->cdbs.work,
-                       delay);
+       /* Do nothing if we recently have sampled */
+       if (delta_us < (s64)(cs_tuners.sampling_rate / 2))
+               sample = false;
+       else
+               dbs_info->cdbs.time_stamp = time_now;
+
+       cs_timer_update(dbs_info, sample, dw);
        mutex_unlock(&dbs_info->cdbs.timer_mutex);
 }
 
+static void cs_dbs_timer(struct work_struct *work)
+{
+       struct delayed_work *dw = to_delayed_work(work);
+       struct cs_cpu_dbs_info_s *dbs_info = container_of(work,
+                       struct cs_cpu_dbs_info_s, cdbs.work.work);
+
+       if (dbs_sw_coordinated_cpus(&dbs_info->cdbs)) {
+               cs_timer_coordinated(dbs_info, dw);
+       } else {
+               mutex_lock(&dbs_info->cdbs.timer_mutex);
+               cs_timer_update(dbs_info, true, dw);
+               mutex_unlock(&dbs_info->cdbs.timer_mutex);
+       }
+}
 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
                void *data)
 {