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>

1 files changed, 41 insertions, 6 deletions

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index b9d7f14d7d3d..5d8e8942ec97 100644
--- 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)
 {