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Subject[PATCH 3/5] cpufreq: ondemand: call dbs_check_cpu only when necessary
Date
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>
---
drivers/cpufreq/cpufreq_governor.c | 3 ++
drivers/cpufreq/cpufreq_governor.h | 1 +
drivers/cpufreq/cpufreq_ondemand.c | 58 +++++++++++++++++++++++++++++++-------
3 files changed, 52 insertions(+), 10 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index e881250..e5a3711 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -333,6 +333,9 @@ 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
--- 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
--- 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,
--
1.7.12.1


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