cpufreq: schedutil: Call sugov_update_next_freq() before check to fast_switch_enabled

From: Yue Hu <[email protected]>

Note that sugov_update_next_freq() may return false, that means the caller sugov_fast_switch() will do nothing except fast switch check.

Similarly, sugov_deferred_update() also has unnecessary operations of raw_spin_{lock,unlock} in sugov_update_single_freq() for that case.

So, let's call sugov_update_next_freq() before the fast switch check to avoid unnecessary behaviors above. Update the related interface definitions accordingly.

Signed-off-by Yue Hu <[email protected]>

---
 kernel/sched/cpufreq_schedutil.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

kernel/sched/cpufreq_schedutil.c +0 -0

index 41e498b..d23e5be 100644

kernel/sched/cpufreq_schedutil.c +12 -10

 }
 
-static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
-				  unsigned int next_freq)
+static void sugov_deferred_update(struct sugov_policy *sg_policy)
 {
-	if (!sugov_update_next_freq(sg_policy, time, next_freq))
-		return;
-
 	if (!sg_policy->work_in_progress) {
 		sg_policy->work_in_progress = true;
 		irq_work_queue(&sg_policy->irq_work);

@@ -368,16 +362,19 @@ static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
 		sg_policy->cached_raw_freq = cached_freq;
 	}
 
+	if (!sugov_update_next_freq(sg_policy, time, next_f))
+		return;
+
 	/*
 	 * This code runs under rq->lock for the target CPU, so it won't run
 	 * concurrently on two different CPUs for the same target and it is not
 	 * necessary to acquire the lock in the fast switch case.
 	 */
 	if (sg_policy->policy->fast_switch_enabled) {
-		sugov_fast_switch(sg_policy, time, next_f);
+		sugov_fast_switch(sg_policy, next_f);
 	} else {
 		raw_spin_lock(&sg_policy->update_lock);
-		sugov_deferred_update(sg_policy, time, next_f);
+		sugov_deferred_update(sg_policy);
 		raw_spin_unlock(&sg_policy->update_lock);
 	}
 }

@@ -456,12 +453,15 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
 	if (sugov_should_update_freq(sg_policy, time)) {
 		next_f = sugov_next_freq_shared(sg_cpu, time);
 
+		if (!sugov_update_next_freq(sg_policy, time, next_f))
+			goto unlock;
+
 		if (sg_policy->policy->fast_switch_enabled)
-			sugov_fast_switch(sg_policy, time, next_f);
+			sugov_fast_switch(sg_policy, next_f);
 		else
-			sugov_deferred_update(sg_policy, time, next_f);
+			sugov_deferred_update(sg_policy);
 	}
-
+unlock:
 	raw_spin_unlock(&sg_policy->update_lock);
 }

Quoted 25 lines · Yue Hu

From: Yue Hu <[email protected]>

Note that sugov_update_next_freq() may return false, that means the caller sugov_fast_switch() will do nothing except fast switch check.

Similarly, sugov_deferred_update() also has unnecessary operations of raw_spin_{lock,unlock} in sugov_update_single_freq() for that case.

So, let's call sugov_update_next_freq() before the fast switch check to avoid unnecessary behaviors above. Update the related interface definitions accordingly.

Signed-off-by Yue Hu <[email protected]>

---
 kernel/sched/cpufreq_schedutil.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

kernel/sched/cpufreq_schedutil.c +0 -0

index 41e498b..d23e5be 100644
@@ -114,19 +114,13 @@ static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
 	return true;
 }
 

kernel/sched/cpufreq_schedutil.c static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time, · line 119

Quoted 7 lines

kernel/sched/cpufreq_schedutil.c +2 -4

-static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
-			      unsigned int next_freq)
+static void sugov_fast_switch(struct sugov_policy *sg_policy, unsigned int next_freq)
 {
-	if (sugov_update_next_freq(sg_policy, time, next_freq))
-		cpufreq_driver_fast_switch(sg_policy->policy, next_freq);
+	cpufreq_driver_fast_switch(sg_policy->policy, next_freq);  

I will call this directly instead, no need of the wrapper anymore.

Quoted 53 lines

kernel/sched/cpufreq_schedutil.c +12 -10

 }
 
-static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
-				  unsigned int next_freq)
+static void sugov_deferred_update(struct sugov_policy *sg_policy)
 {
-	if (!sugov_update_next_freq(sg_policy, time, next_freq))
-		return;
-
 	if (!sg_policy->work_in_progress) {
 		sg_policy->work_in_progress = true;
 		irq_work_queue(&sg_policy->irq_work);

@@ -368,16 +362,19 @@ static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
 		sg_policy->cached_raw_freq = cached_freq;
 	}
 
+	if (!sugov_update_next_freq(sg_policy, time, next_f))
+		return;
+
 	/*
 	 * This code runs under rq->lock for the target CPU, so it won't run
 	 * concurrently on two different CPUs for the same target and it is not
 	 * necessary to acquire the lock in the fast switch case.
 	 */
 	if (sg_policy->policy->fast_switch_enabled) {
-		sugov_fast_switch(sg_policy, time, next_f);
+		sugov_fast_switch(sg_policy, next_f);
 	} else {
 		raw_spin_lock(&sg_policy->update_lock);
-		sugov_deferred_update(sg_policy, time, next_f);
+		sugov_deferred_update(sg_policy);
 		raw_spin_unlock(&sg_policy->update_lock);
 	}
 }

@@ -456,12 +453,15 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
 	if (sugov_should_update_freq(sg_policy, time)) {
 		next_f = sugov_next_freq_shared(sg_cpu, time);
 
+		if (!sugov_update_next_freq(sg_policy, time, next_f))
+			goto unlock;
+
 		if (sg_policy->policy->fast_switch_enabled)
-			sugov_fast_switch(sg_policy, time, next_f);
+			sugov_fast_switch(sg_policy, next_f);
 		else
-			sugov_deferred_update(sg_policy, time, next_f);
+			sugov_deferred_update(sg_policy);
 	}
-
+unlock:
 	raw_spin_unlock(&sg_policy->update_lock);
 }  

From: Yue Hu <[email protected]>

Note that sugov_update_next_freq() may return false, that means the caller sugov_fast_switch() will do nothing except fast switch check.

Similarly, sugov_deferred_update() also has unnecessary operations of raw_spin_{lock,unlock} in sugov_update_single_freq() for that case.

So, let's call sugov_update_next_freq() before the fast switch check to avoid unnecessary behaviors above. Update the related interface definitions accordingly.

Signed-off-by Yue Hu <[email protected]>

---
 kernel/sched/cpufreq_schedutil.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

kernel/sched/cpufreq_schedutil.c +12 -12

index 41e498b..d23e5be 100644
@@ -114,19 +114,13 @@ static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
        return true;
 }
 
-static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
-                             unsigned int next_freq)
+static void sugov_fast_switch(struct sugov_policy *sg_policy, unsigned int next_freq)
 {
-       if (sugov_update_next_freq(sg_policy, time, next_freq))
-               cpufreq_driver_fast_switch(sg_policy->policy, next_freq);
+       cpufreq_driver_fast_switch(sg_policy->policy, next_freq);
 }
 
-static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
-                                 unsigned int next_freq)
+static void sugov_deferred_update(struct sugov_policy *sg_policy)
 {
-       if (!sugov_update_next_freq(sg_policy, time, next_freq))
-               return;
-
        if (!sg_policy->work_in_progress) {
                sg_policy->work_in_progress = true;
                irq_work_queue(&sg_policy->irq_work);

@@ -368,16 +362,19 @@ static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
                sg_policy->cached_raw_freq = cached_freq;
        }
 
+       if (!sugov_update_next_freq(sg_policy, time, next_f))
+               return;
+
        /*
         * This code runs under rq->lock for the target CPU, so it won't run
         * concurrently on two different CPUs for the same target and it is not
         * necessary to acquire the lock in the fast switch case.
         */
        if (sg_policy->policy->fast_switch_enabled) {
-               sugov_fast_switch(sg_policy, time, next_f);
+               sugov_fast_switch(sg_policy, next_f);
        } else {
                raw_spin_lock(&sg_policy->update_lock);
-               sugov_deferred_update(sg_policy, time, next_f);
+               sugov_deferred_update(sg_policy);
                raw_spin_unlock(&sg_policy->update_lock);
        }
 }

@@ -456,12 +453,15 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
        if (sugov_should_update_freq(sg_policy, time)) {
                next_f = sugov_next_freq_shared(sg_cpu, time);
 
+               if (!sugov_update_next_freq(sg_policy, time, next_f))
+                       goto unlock;
+
                if (sg_policy->policy->fast_switch_enabled)
-                       sugov_fast_switch(sg_policy, time, next_f);
+                       sugov_fast_switch(sg_policy, next_f);