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Subject[PATCH 4/5] cpufreq: conservative: call dbs_check_cpu only when necessary
Date
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>
---
drivers/cpufreq/cpufreq_conservative.c | 47 +++++++++++++++++++++++++++++-----
1 file changed, 41 insertions(+), 6 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index b9d7f14..5d8e894 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)
{
--
1.7.12.1


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