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-rw-r--r--drivers/cpufreq/Kconfig1
-rw-r--r--drivers/cpufreq/cpufreq_conservative.c6
-rw-r--r--drivers/cpufreq/cpufreq_governor.c165
-rw-r--r--drivers/cpufreq/cpufreq_governor.h19
-rw-r--r--drivers/cpufreq/cpufreq_ondemand.c43
5 files changed, 114 insertions, 120 deletions
diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 659879a56dba..dcb972a38fbc 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -3,6 +3,7 @@ menu "CPU Frequency scaling"
config CPU_FREQ
bool "CPU Frequency scaling"
select SRCU
+ select IRQ_WORK
help
CPU Frequency scaling allows you to change the clock speed of
CPUs on the fly. This is a nice method to save power, because
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index 8504a70a4785..bc002c8cba90 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -112,14 +112,12 @@ static void cs_check_cpu(int cpu, unsigned int load)
}
}
-static unsigned int cs_dbs_timer(struct cpufreq_policy *policy, bool modify_all)
+static unsigned int cs_dbs_timer(struct cpufreq_policy *policy)
{
struct dbs_data *dbs_data = policy->governor_data;
struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
- if (modify_all)
- dbs_check_cpu(dbs_data, policy->cpu);
-
+ dbs_check_cpu(dbs_data, policy->cpu);
return delay_for_sampling_rate(cs_tuners->sampling_rate);
}
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index e0d111024d48..6bc2f50cc1d9 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -128,10 +128,10 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
* dropped down. So we perform the copy only once, upon the
* first wake-up from idle.)
*
- * Detecting this situation is easy: the governor's deferrable
- * timer would not have fired during CPU-idle periods. Hence
- * an unusually large 'wall_time' (as compared to the sampling
- * rate) indicates this scenario.
+ * Detecting this situation is easy: the governor's utilization
+ * update handler would not have run during CPU-idle periods.
+ * Hence, an unusually large 'wall_time' (as compared to the
+ * sampling rate) indicates this scenario.
*
* prev_load can be zero in two cases and we must recalculate it
* for both cases:
@@ -161,72 +161,48 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
}
EXPORT_SYMBOL_GPL(dbs_check_cpu);
-void gov_add_timers(struct cpufreq_policy *policy, unsigned int delay)
+void gov_set_update_util(struct cpu_common_dbs_info *shared,
+ unsigned int delay_us)
{
+ struct cpufreq_policy *policy = shared->policy;
struct dbs_data *dbs_data = policy->governor_data;
- struct cpu_dbs_info *cdbs;
int cpu;
+ gov_update_sample_delay(shared, delay_us);
+ shared->last_sample_time = 0;
+
for_each_cpu(cpu, policy->cpus) {
- cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
- cdbs->timer.expires = jiffies + delay;
- add_timer_on(&cdbs->timer, cpu);
+ struct cpu_dbs_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
+
+ cpufreq_set_update_util_data(cpu, &cdbs->update_util);
}
}
-EXPORT_SYMBOL_GPL(gov_add_timers);
+EXPORT_SYMBOL_GPL(gov_set_update_util);
-static inline void gov_cancel_timers(struct cpufreq_policy *policy)
+static inline void gov_clear_update_util(struct cpufreq_policy *policy)
{
- struct dbs_data *dbs_data = policy->governor_data;
- struct cpu_dbs_info *cdbs;
int i;
- for_each_cpu(i, policy->cpus) {
- cdbs = dbs_data->cdata->get_cpu_cdbs(i);
- del_timer_sync(&cdbs->timer);
- }
+ for_each_cpu(i, policy->cpus)
+ cpufreq_set_update_util_data(i, NULL);
+
+ synchronize_rcu();
}
-void gov_cancel_work(struct cpu_common_dbs_info *shared)
+static void gov_cancel_work(struct cpu_common_dbs_info *shared)
{
- /* Tell dbs_timer_handler() to skip queuing up work items. */
+ /* Tell dbs_update_util_handler() to skip queuing up work items. */
atomic_inc(&shared->skip_work);
/*
- * If dbs_timer_handler() is already running, it may not notice the
- * incremented skip_work, so wait for it to complete to prevent its work
- * item from being queued up after the cancel_work_sync() below.
- */
- gov_cancel_timers(shared->policy);
- /*
- * In case dbs_timer_handler() managed to run and spawn a work item
- * before the timers have been canceled, wait for that work item to
- * complete and then cancel all of the timers set up by it. If
- * dbs_timer_handler() runs again at that point, it will see the
- * positive value of skip_work and won't spawn any more work items.
+ * If dbs_update_util_handler() is already running, it may not notice
+ * the incremented skip_work, so wait for it to complete to prevent its
+ * work item from being queued up after the cancel_work_sync() below.
*/
+ gov_clear_update_util(shared->policy);
+ irq_work_sync(&shared->irq_work);
cancel_work_sync(&shared->work);
- gov_cancel_timers(shared->policy);
atomic_set(&shared->skip_work, 0);
}
-EXPORT_SYMBOL_GPL(gov_cancel_work);
-
-/* Will return if we need to evaluate cpu load again or not */
-static bool need_load_eval(struct cpu_common_dbs_info *shared,
- unsigned int sampling_rate)
-{
- if (policy_is_shared(shared->policy)) {
- ktime_t time_now = ktime_get();
- s64 delta_us = ktime_us_delta(time_now, shared->time_stamp);
-
- /* Do nothing if we recently have sampled */
- if (delta_us < (s64)(sampling_rate / 2))
- return false;
- else
- shared->time_stamp = time_now;
- }
-
- return true;
-}
static void dbs_work_handler(struct work_struct *work)
{
@@ -234,56 +210,70 @@ static void dbs_work_handler(struct work_struct *work)
cpu_common_dbs_info, work);
struct cpufreq_policy *policy;
struct dbs_data *dbs_data;
- unsigned int sampling_rate, delay;
- bool eval_load;
+ unsigned int delay;
policy = shared->policy;
dbs_data = policy->governor_data;
- /* Kill all timers */
- gov_cancel_timers(policy);
-
- if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
- struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
-
- sampling_rate = cs_tuners->sampling_rate;
- } else {
- struct od_dbs_tuners *od_tuners = dbs_data->tuners;
-
- sampling_rate = od_tuners->sampling_rate;
- }
-
- eval_load = need_load_eval(shared, sampling_rate);
-
/*
- * Make sure cpufreq_governor_limits() isn't evaluating load in
- * parallel.
+ * Make sure cpufreq_governor_limits() isn't evaluating load or the
+ * ondemand governor isn't updating the sampling rate in parallel.
*/
mutex_lock(&shared->timer_mutex);
- delay = dbs_data->cdata->gov_dbs_timer(policy, eval_load);
+ delay = dbs_data->cdata->gov_dbs_timer(policy);
+ shared->sample_delay_ns = jiffies_to_nsecs(delay);
mutex_unlock(&shared->timer_mutex);
+ /*
+ * If the atomic operation below is reordered with respect to the
+ * sample delay modification, the utilization update handler may end
+ * up using a stale sample delay value.
+ */
+ smp_mb__before_atomic();
atomic_dec(&shared->skip_work);
+}
+
+static void dbs_irq_work(struct irq_work *irq_work)
+{
+ struct cpu_common_dbs_info *shared;
- gov_add_timers(policy, delay);
+ shared = container_of(irq_work, struct cpu_common_dbs_info, irq_work);
+ schedule_work(&shared->work);
}
-static void dbs_timer_handler(unsigned long data)
+static inline void gov_queue_irq_work(struct cpu_common_dbs_info *shared)
{
- struct cpu_dbs_info *cdbs = (struct cpu_dbs_info *)data;
+#ifdef CONFIG_SMP
+ irq_work_queue_on(&shared->irq_work, smp_processor_id());
+#else
+ irq_work_queue(&shared->irq_work);
+#endif
+}
+
+static void dbs_update_util_handler(struct update_util_data *data, u64 time,
+ unsigned long util, unsigned long max)
+{
+ struct cpu_dbs_info *cdbs = container_of(data, struct cpu_dbs_info, update_util);
struct cpu_common_dbs_info *shared = cdbs->shared;
/*
- * Timer handler may not be allowed to queue the work at the moment,
- * because:
- * - Another timer handler has done that
- * - We are stopping the governor
- * - Or we are updating the sampling rate of the ondemand governor
+ * The work may not be allowed to be queued up right now.
+ * Possible reasons:
+ * - Work has already been queued up or is in progress.
+ * - The governor is being stopped.
+ * - It is too early (too little time from the previous sample).
*/
- if (atomic_inc_return(&shared->skip_work) > 1)
- atomic_dec(&shared->skip_work);
- else
- queue_work(system_wq, &shared->work);
+ if (atomic_inc_return(&shared->skip_work) == 1) {
+ u64 delta_ns;
+
+ delta_ns = time - shared->last_sample_time;
+ if ((s64)delta_ns >= shared->sample_delay_ns) {
+ shared->last_sample_time = time;
+ gov_queue_irq_work(shared);
+ return;
+ }
+ }
+ atomic_dec(&shared->skip_work);
}
static void set_sampling_rate(struct dbs_data *dbs_data,
@@ -315,6 +305,7 @@ static int alloc_common_dbs_info(struct cpufreq_policy *policy,
mutex_init(&shared->timer_mutex);
atomic_set(&shared->skip_work, 0);
+ init_irq_work(&shared->irq_work, dbs_irq_work);
INIT_WORK(&shared->work, dbs_work_handler);
return 0;
}
@@ -467,9 +458,6 @@ static int cpufreq_governor_start(struct cpufreq_policy *policy,
io_busy = od_tuners->io_is_busy;
}
- shared->policy = policy;
- shared->time_stamp = ktime_get();
-
for_each_cpu(j, policy->cpus) {
struct cpu_dbs_info *j_cdbs = cdata->get_cpu_cdbs(j);
unsigned int prev_load;
@@ -485,10 +473,9 @@ static int cpufreq_governor_start(struct cpufreq_policy *policy,
if (ignore_nice)
j_cdbs->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
- __setup_timer(&j_cdbs->timer, dbs_timer_handler,
- (unsigned long)j_cdbs,
- TIMER_DEFERRABLE | TIMER_IRQSAFE);
+ j_cdbs->update_util.func = dbs_update_util_handler;
}
+ shared->policy = policy;
if (cdata->governor == GOV_CONSERVATIVE) {
struct cs_cpu_dbs_info_s *cs_dbs_info =
@@ -505,7 +492,7 @@ static int cpufreq_governor_start(struct cpufreq_policy *policy,
od_ops->powersave_bias_init_cpu(cpu);
}
- gov_add_timers(policy, delay_for_sampling_rate(sampling_rate));
+ gov_set_update_util(shared, sampling_rate);
return 0;
}
diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
index 91e767a058a7..541777192dbc 100644
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -18,6 +18,7 @@
#define _CPUFREQ_GOVERNOR_H
#include <linux/atomic.h>
+#include <linux/irq_work.h>
#include <linux/cpufreq.h>
#include <linux/kernel_stat.h>
#include <linux/module.h>
@@ -138,11 +139,19 @@ struct cpu_common_dbs_info {
*/
struct mutex timer_mutex;
- ktime_t time_stamp;
+ u64 last_sample_time;
+ s64 sample_delay_ns;
atomic_t skip_work;
+ struct irq_work irq_work;
struct work_struct work;
};
+static inline void gov_update_sample_delay(struct cpu_common_dbs_info *shared,
+ unsigned int delay_us)
+{
+ shared->sample_delay_ns = delay_us * NSEC_PER_USEC;
+}
+
/* Per cpu structures */
struct cpu_dbs_info {
u64 prev_cpu_idle;
@@ -155,7 +164,7 @@ struct cpu_dbs_info {
* wake-up from idle.
*/
unsigned int prev_load;
- struct timer_list timer;
+ struct update_util_data update_util;
struct cpu_common_dbs_info *shared;
};
@@ -212,8 +221,7 @@ struct common_dbs_data {
struct cpu_dbs_info *(*get_cpu_cdbs)(int cpu);
void *(*get_cpu_dbs_info_s)(int cpu);
- unsigned int (*gov_dbs_timer)(struct cpufreq_policy *policy,
- bool modify_all);
+ unsigned int (*gov_dbs_timer)(struct cpufreq_policy *policy);
void (*gov_check_cpu)(int cpu, unsigned int load);
int (*init)(struct dbs_data *dbs_data, bool notify);
void (*exit)(struct dbs_data *dbs_data, bool notify);
@@ -270,9 +278,6 @@ static ssize_t show_sampling_rate_min_gov_pol \
}
extern struct mutex cpufreq_governor_lock;
-
-void gov_add_timers(struct cpufreq_policy *policy, unsigned int delay);
-void gov_cancel_work(struct cpu_common_dbs_info *shared);
void dbs_check_cpu(struct dbs_data *dbs_data, int cpu);
int cpufreq_governor_dbs(struct cpufreq_policy *policy,
struct common_dbs_data *cdata, unsigned int event);
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 929e193ac1c1..da7f3514d948 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -189,7 +189,7 @@ static void od_check_cpu(int cpu, unsigned int load)
}
}
-static unsigned int od_dbs_timer(struct cpufreq_policy *policy, bool modify_all)
+static unsigned int od_dbs_timer(struct cpufreq_policy *policy)
{
struct dbs_data *dbs_data = policy->governor_data;
unsigned int cpu = policy->cpu;
@@ -198,9 +198,6 @@ static unsigned int od_dbs_timer(struct cpufreq_policy *policy, bool modify_all)
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
int delay = 0, sample_type = dbs_info->sample_type;
- if (!modify_all)
- goto max_delay;
-
/* Common NORMAL_SAMPLE setup */
dbs_info->sample_type = OD_NORMAL_SAMPLE;
if (sample_type == OD_SUB_SAMPLE) {
@@ -216,7 +213,6 @@ static unsigned int od_dbs_timer(struct cpufreq_policy *policy, bool modify_all)
}
}
-max_delay:
if (!delay)
delay = delay_for_sampling_rate(od_tuners->sampling_rate
* dbs_info->rate_mult);
@@ -262,7 +258,6 @@ static void update_sampling_rate(struct dbs_data *dbs_data,
struct od_cpu_dbs_info_s *dbs_info;
struct cpu_dbs_info *cdbs;
struct cpu_common_dbs_info *shared;
- unsigned long next_sampling, appointed_at;
dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
cdbs = &dbs_info->cdbs;
@@ -286,20 +281,28 @@ static void update_sampling_rate(struct dbs_data *dbs_data,
* policy will be governed by dbs_data, otherwise there can be
* multiple policies that are governed by the same dbs_data.
*/
- if (dbs_data != policy->governor_data)
- continue;
-
- /*
- * Checking this for any CPU should be fine, timers for all of
- * them are scheduled together.
- */
- next_sampling = jiffies + usecs_to_jiffies(new_rate);
- appointed_at = dbs_info->cdbs.timer.expires;
-
- if (time_before(next_sampling, appointed_at)) {
- gov_cancel_work(shared);
- gov_add_timers(policy, usecs_to_jiffies(new_rate));
-
+ if (dbs_data == policy->governor_data) {
+ mutex_lock(&shared->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(shared, new_rate);
+ mutex_unlock(&shared->timer_mutex);
}
}
generated by cgit (git 2.34.1) at 2024-06-07 04:57:03 +0000