@@ -26,10 +26,29 @@ DEFINE_MUTEX(dbs_data_mutex);
EXPORT_SYMBOL_GPL(dbs_data_mutex);
/* Common sysfs tunables */
+/**
+ * update_sampling_rate - update sampling rate effective immediately if needed.
+ *
+ * If new rate is smaller than the old, simply updating
+ * dbs.sampling_rate might not be appropriate. For example, if the
+ * original sampling_rate was 1 second and the requested new sampling rate is 10
+ * ms because the user needs immediate reaction from ondemand governor, but not
+ * sure if higher frequency will be required or not, then, the governor may
+ * change the sampling rate too late; up to 1 second later. Thus, if we are
+ * reducing the sampling rate, we need to make the new value effective
+ * immediately.
+ *
+ * On the other hand, if new rate is larger than the old, then we may evaluate
+ * the load too soon, and it might we worth updating sample_delay_ns then as
+ * well.
+ *
+ * This must be called with dbs_data->mutex held, otherwise traversing
+ * policy_dbs_list isn't safe.
+ */
static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
size_t count)
{
- struct dbs_governor *gov = dbs_data->gov;
+ struct policy_dbs_info *policy_dbs;
unsigned int rate;
int ret;
ret = sscanf(buf, "%u", &rate);
@@ -38,8 +57,32 @@ static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
dbs_data->sampling_rate = max(rate, dbs_data->min_sampling_rate);
- if (gov->update_sampling_rate)
- gov->update_sampling_rate(dbs_data);
+ /*
+ * We are operating under dbs_data->mutex and so the list and its
+ * entries can't be freed concurrently.
+ */
+ list_for_each_entry(policy_dbs, &dbs_data->policy_dbs_list, list) {
+ mutex_lock(&policy_dbs->timer_mutex);
+ /*
+ * On 32-bit architectures this may race with the
+ * sample_delay_ns read in dbs_update_util_handler(), but that
+ * really doesn't matter. If the read returns a value that's
+ * too big, the sample will be skipped, but the next invocation
+ * of dbs_update_util_handler() (when the update has been
+ * completed) will take a sample. If the returned value is too
+ * small, the sample will be taken immediately, but that isn't a
+ * problem, as we want the new rate to take effect immediately
+ * anyway.
+ *
+ * If this runs in parallel with dbs_work_handler(), we may end
+ * up overwriting the sample_delay_ns value that it has just
+ * written, but the difference should not be too big and it will
+ * be corrected next time a sample is taken, so it shouldn't be
+ * significant.
+ */
+ gov_update_sample_delay(policy_dbs, dbs_data->sampling_rate);
+ mutex_unlock(&policy_dbs->timer_mutex);
+ }
return count;
}
@@ -211,7 +211,6 @@ struct dbs_governor {
void (*exit)(struct dbs_data *dbs_data, bool notify);
bool (*invalid_up_threshold)(struct dbs_data *dbs_data, unsigned int threshold);
bool (*invalid_sampling_down_factor)(unsigned int factor);
- void (*update_sampling_rate)(struct dbs_data *dbs_data);
void (*update_sampling_down_factor)(struct dbs_data *dbs_data);
void (*update_ignore_nice_load)(struct dbs_data *dbs_data);
@@ -221,57 +221,6 @@ static unsigned int od_dbs_timer(struct cpufreq_policy *policy)
/************************** sysfs interface ************************/
static struct dbs_governor od_dbs_gov;
-/**
- * update_sampling_rate - update sampling rate effective immediately if needed.
- *
- * If new rate is smaller than the old, simply updating
- * dbs.sampling_rate might not be appropriate. For example, if the
- * original sampling_rate was 1 second and the requested new sampling rate is 10
- * ms because the user needs immediate reaction from ondemand governor, but not
- * sure if higher frequency will be required or not, then, the governor may
- * change the sampling rate too late; up to 1 second later. Thus, if we are
- * reducing the sampling rate, we need to make the new value effective
- * immediately.
- *
- * On the other hand, if new rate is larger than the old, then we may evaluate
- * the load too soon, and it might we worth updating sample_delay_ns then as
- * well.
- *
- * This must be called with dbs_data->mutex held, otherwise traversing
- * policy_dbs_list isn't safe.
- */
-static void update_sampling_rate(struct dbs_data *dbs_data)
-{
- struct policy_dbs_info *policy_dbs;
-
- /*
- * We are operating under dbs_data->mutex and so the list and its
- * entries can't be freed concurrently.
- */
- list_for_each_entry(policy_dbs, &dbs_data->policy_dbs_list, list) {
- mutex_lock(&policy_dbs->timer_mutex);
- /*
- * On 32-bit architectures this may race with the
- * sample_delay_ns read in dbs_update_util_handler(), but that
- * really doesn't matter. If the read returns a value that's
- * too big, the sample will be skipped, but the next invocation
- * of dbs_update_util_handler() (when the update has been
- * completed) will take a sample. If the returned value is too
- * small, the sample will be taken immediately, but that isn't a
- * problem, as we want the new rate to take effect immediately
- * anyway.
- *
- * If this runs in parallel with dbs_work_handler(), we may end
- * up overwriting the sample_delay_ns value that it has just
- * written, but the difference should not be too big and it will
- * be corrected next time a sample is taken, so it shouldn't be
- * significant.
- */
- gov_update_sample_delay(policy_dbs, dbs_data->sampling_rate);
- mutex_unlock(&policy_dbs->timer_mutex);
- }
-}
-
static bool invalid_up_threshold(struct dbs_data *dbs_data,
unsigned int threshold)
{
@@ -438,7 +387,6 @@ static struct dbs_governor od_dbs_gov = {
.get_cpu_dbs_info_s = get_cpu_dbs_info_s,
.gov_dbs_timer = od_dbs_timer,
.gov_check_cpu = od_check_cpu,
- .update_sampling_rate = update_sampling_rate,
.invalid_up_threshold = invalid_up_threshold,
.invalid_sampling_down_factor = invalid_sampling_down_factor,
.update_sampling_down_factor = update_sampling_down_factor,