X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fsched_rt.c;h=908c04f9dad02d23df66fbc55a28f5619fc10081;hb=2e489e077a6ad118c4f247faedf330117b107cce;hp=837241568d767a2f0b25298544921088bfba4941;hpb=ad2a3f13b7258a5daaaeb8cff9f835aac468b71d;p=safe%2Fjmp%2Flinux-2.6

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 8372415..908c04f 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -12,6 +12,9 @@ static inline int rt_overloaded(struct rq *rq)
 
 static inline void rt_set_overload(struct rq *rq)
 {
+	if (!rq->online)
+		return;
+
 	cpu_set(rq->cpu, rq->rd->rto_mask);
 	/*
 	 * Make sure the mask is visible before we set
@@ -26,6 +29,9 @@ static inline void rt_set_overload(struct rq *rq)
 
 static inline void rt_clear_overload(struct rq *rq)
 {
+	if (!rq->online)
+		return;
+
 	/* the order here really doesn't matter */
 	atomic_dec(&rq->rd->rto_count);
 	cpu_clear(rq->cpu, rq->rd->rto_mask);
@@ -155,7 +161,7 @@ static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
 	return &rt_rq->tg->rt_bandwidth;
 }
 
-#else
+#else /* !CONFIG_RT_GROUP_SCHED */
 
 static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
 {
@@ -220,48 +226,10 @@ static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
 	return &def_rt_bandwidth;
 }
 
-#endif
-
-static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
-{
-	int i, idle = 1;
-	cpumask_t span;
-
-	if (rt_b->rt_runtime == RUNTIME_INF)
-		return 1;
-
-	span = sched_rt_period_mask();
-	for_each_cpu_mask(i, span) {
-		int enqueue = 0;
-		struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
-		struct rq *rq = rq_of_rt_rq(rt_rq);
-
-		spin_lock(&rq->lock);
-		if (rt_rq->rt_time) {
-			u64 runtime;
-
-			spin_lock(&rt_rq->rt_runtime_lock);
-			runtime = rt_rq->rt_runtime;
-			rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
-			if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
-				rt_rq->rt_throttled = 0;
-				enqueue = 1;
-			}
-			if (rt_rq->rt_time || rt_rq->rt_nr_running)
-				idle = 0;
-			spin_unlock(&rt_rq->rt_runtime_lock);
-		}
-
-		if (enqueue)
-			sched_rt_rq_enqueue(rt_rq);
-		spin_unlock(&rq->lock);
-	}
-
-	return idle;
-}
+#endif /* CONFIG_RT_GROUP_SCHED */
 
 #ifdef CONFIG_SMP
-static int balance_runtime(struct rt_rq *rt_rq)
+static int do_balance_runtime(struct rt_rq *rt_rq)
 {
 	struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
 	struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
@@ -272,7 +240,7 @@ static int balance_runtime(struct rt_rq *rt_rq)
 
 	spin_lock(&rt_b->rt_runtime_lock);
 	rt_period = ktime_to_ns(rt_b->rt_period);
-	for_each_cpu_mask(i, rd->span) {
+	for_each_cpu_mask_nr(i, rd->span) {
 		struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
 		s64 diff;
 
@@ -280,9 +248,12 @@ static int balance_runtime(struct rt_rq *rt_rq)
 			continue;
 
 		spin_lock(&iter->rt_runtime_lock);
+		if (iter->rt_runtime == RUNTIME_INF)
+			goto next;
+
 		diff = iter->rt_runtime - iter->rt_time;
 		if (diff > 0) {
-			do_div(diff, weight);
+			diff = div_u64((u64)diff, weight);
 			if (rt_rq->rt_runtime + diff > rt_period)
 				diff = rt_period - rt_rq->rt_runtime;
 			iter->rt_runtime -= diff;
@@ -293,13 +264,163 @@ static int balance_runtime(struct rt_rq *rt_rq)
 				break;
 			}
 		}
+next:
 		spin_unlock(&iter->rt_runtime_lock);
 	}
 	spin_unlock(&rt_b->rt_runtime_lock);
 
 	return more;
 }
-#endif
+
+static void __disable_runtime(struct rq *rq)
+{
+	struct root_domain *rd = rq->rd;
+	struct rt_rq *rt_rq;
+
+	if (unlikely(!scheduler_running))
+		return;
+
+	for_each_leaf_rt_rq(rt_rq, rq) {
+		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
+		s64 want;
+		int i;
+
+		spin_lock(&rt_b->rt_runtime_lock);
+		spin_lock(&rt_rq->rt_runtime_lock);
+		if (rt_rq->rt_runtime == RUNTIME_INF ||
+				rt_rq->rt_runtime == rt_b->rt_runtime)
+			goto balanced;
+		spin_unlock(&rt_rq->rt_runtime_lock);
+
+		want = rt_b->rt_runtime - rt_rq->rt_runtime;
+
+		for_each_cpu_mask(i, rd->span) {
+			struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
+			s64 diff;
+
+			if (iter == rt_rq)
+				continue;
+
+			spin_lock(&iter->rt_runtime_lock);
+			if (want > 0) {
+				diff = min_t(s64, iter->rt_runtime, want);
+				iter->rt_runtime -= diff;
+				want -= diff;
+			} else {
+				iter->rt_runtime -= want;
+				want -= want;
+			}
+			spin_unlock(&iter->rt_runtime_lock);
+
+			if (!want)
+				break;
+		}
+
+		spin_lock(&rt_rq->rt_runtime_lock);
+		BUG_ON(want);
+balanced:
+		rt_rq->rt_runtime = RUNTIME_INF;
+		spin_unlock(&rt_rq->rt_runtime_lock);
+		spin_unlock(&rt_b->rt_runtime_lock);
+	}
+}
+
+static void disable_runtime(struct rq *rq)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rq->lock, flags);
+	__disable_runtime(rq);
+	spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+static void __enable_runtime(struct rq *rq)
+{
+	struct rt_rq *rt_rq;
+
+	if (unlikely(!scheduler_running))
+		return;
+
+	for_each_leaf_rt_rq(rt_rq, rq) {
+		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
+
+		spin_lock(&rt_b->rt_runtime_lock);
+		spin_lock(&rt_rq->rt_runtime_lock);
+		rt_rq->rt_runtime = rt_b->rt_runtime;
+		rt_rq->rt_time = 0;
+		spin_unlock(&rt_rq->rt_runtime_lock);
+		spin_unlock(&rt_b->rt_runtime_lock);
+	}
+}
+
+static void enable_runtime(struct rq *rq)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rq->lock, flags);
+	__enable_runtime(rq);
+	spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+static int balance_runtime(struct rt_rq *rt_rq)
+{
+	int more = 0;
+
+	if (rt_rq->rt_time > rt_rq->rt_runtime) {
+		spin_unlock(&rt_rq->rt_runtime_lock);
+		more = do_balance_runtime(rt_rq);
+		spin_lock(&rt_rq->rt_runtime_lock);
+	}
+
+	return more;
+}
+#else /* !CONFIG_SMP */
+static inline int balance_runtime(struct rt_rq *rt_rq)
+{
+	return 0;
+}
+#endif /* CONFIG_SMP */
+
+static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
+{
+	int i, idle = 1;
+	cpumask_t span;
+
+	if (rt_b->rt_runtime == RUNTIME_INF)
+		return 1;
+
+	span = sched_rt_period_mask();
+	for_each_cpu_mask(i, span) {
+		int enqueue = 0;
+		struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
+		struct rq *rq = rq_of_rt_rq(rt_rq);
+
+		spin_lock(&rq->lock);
+		if (rt_rq->rt_time) {
+			u64 runtime;
+
+			spin_lock(&rt_rq->rt_runtime_lock);
+			if (rt_rq->rt_throttled)
+				balance_runtime(rt_rq);
+			runtime = rt_rq->rt_runtime;
+			rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
+			if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
+				rt_rq->rt_throttled = 0;
+				enqueue = 1;
+			}
+			if (rt_rq->rt_time || rt_rq->rt_nr_running)
+				idle = 0;
+			spin_unlock(&rt_rq->rt_runtime_lock);
+		} else if (rt_rq->rt_nr_running)
+			idle = 0;
+
+		if (enqueue)
+			sched_rt_rq_enqueue(rt_rq);
+		spin_unlock(&rq->lock);
+	}
+
+	return idle;
+}
 
 static inline int rt_se_prio(struct sched_rt_entity *rt_se)
 {
@@ -326,18 +447,10 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
 	if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))
 		return 0;
 
-#ifdef CONFIG_SMP
-	if (rt_rq->rt_time > runtime) {
-		int more;
-
-		spin_unlock(&rt_rq->rt_runtime_lock);
-		more = balance_runtime(rt_rq);
-		spin_lock(&rt_rq->rt_runtime_lock);
-
-		if (more)
-			runtime = sched_rt_runtime(rt_rq);
-	}
-#endif
+	balance_runtime(rt_rq);
+	runtime = sched_rt_runtime(rt_rq);
+	if (runtime == RUNTIME_INF)
+		return 0;
 
 	if (rt_rq->rt_time > runtime) {
 		rt_rq->rt_throttled = 1;
@@ -391,12 +504,23 @@ void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 	WARN_ON(!rt_prio(rt_se_prio(rt_se)));
 	rt_rq->rt_nr_running++;
 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
-	if (rt_se_prio(rt_se) < rt_rq->highest_prio)
+	if (rt_se_prio(rt_se) < rt_rq->highest_prio) {
+#ifdef CONFIG_SMP
+		struct rq *rq = rq_of_rt_rq(rt_rq);
+#endif
+
 		rt_rq->highest_prio = rt_se_prio(rt_se);
+#ifdef CONFIG_SMP
+		if (rq->online)
+			cpupri_set(&rq->rd->cpupri, rq->cpu,
+				   rt_se_prio(rt_se));
+#endif
+	}
 #endif
 #ifdef CONFIG_SMP
 	if (rt_se->nr_cpus_allowed > 1) {
 		struct rq *rq = rq_of_rt_rq(rt_rq);
+
 		rq->rt.rt_nr_migratory++;
 	}
 
@@ -416,6 +540,10 @@ void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 static inline
 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 {
+#ifdef CONFIG_SMP
+	int highest_prio = rt_rq->highest_prio;
+#endif
+
 	WARN_ON(!rt_prio(rt_se_prio(rt_se)));
 	WARN_ON(!rt_rq->rt_nr_running);
 	rt_rq->rt_nr_running--;
@@ -439,6 +567,14 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 		rq->rt.rt_nr_migratory--;
 	}
 
+	if (rt_rq->highest_prio != highest_prio) {
+		struct rq *rq = rq_of_rt_rq(rt_rq);
+
+		if (rq->online)
+			cpupri_set(&rq->rd->cpupri, rq->cpu,
+				   rt_rq->highest_prio);
+	}
+
 	update_rt_migration(rq_of_rt_rq(rt_rq));
 #endif /* CONFIG_SMP */
 #ifdef CONFIG_RT_GROUP_SCHED
@@ -454,6 +590,7 @@ static void __enqueue_rt_entity(struct sched_rt_entity *rt_se)
 	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
 	struct rt_prio_array *array = &rt_rq->active;
 	struct rt_rq *group_rq = group_rt_rq(rt_se);
+	struct list_head *queue = array->queue + rt_se_prio(rt_se);
 
 	/*
 	 * Don't enqueue the group if its throttled, or when empty.
@@ -464,7 +601,7 @@ static void __enqueue_rt_entity(struct sched_rt_entity *rt_se)
 	if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
 		return;
 
-	list_add_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
+	list_add_tail(&rt_se->run_list, queue);
 	__set_bit(rt_se_prio(rt_se), array->bitmap);
 
 	inc_rt_tasks(rt_se, rt_rq);
@@ -531,6 +668,8 @@ static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
 		rt_se->timeout = 0;
 
 	enqueue_rt_entity(rt_se);
+
+	inc_cpu_load(rq, p->se.load.weight);
 }
 
 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
@@ -539,34 +678,42 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
 
 	update_curr_rt(rq);
 	dequeue_rt_entity(rt_se);
+
+	dec_cpu_load(rq, p->se.load.weight);
 }
 
 /*
  * Put task to the end of the run list without the overhead of dequeue
  * followed by enqueue.
  */
-static
-void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
+static void
+requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
 {
-	struct rt_prio_array *array = &rt_rq->active;
+	if (on_rt_rq(rt_se)) {
+		struct rt_prio_array *array = &rt_rq->active;
+		struct list_head *queue = array->queue + rt_se_prio(rt_se);
 
-	list_move_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
+		if (head)
+			list_move(&rt_se->run_list, queue);
+		else
+			list_move_tail(&rt_se->run_list, queue);
+	}
 }
 
-static void requeue_task_rt(struct rq *rq, struct task_struct *p)
+static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
 {
 	struct sched_rt_entity *rt_se = &p->rt;
 	struct rt_rq *rt_rq;
 
 	for_each_sched_rt_entity(rt_se) {
 		rt_rq = rt_rq_of_se(rt_se);
-		requeue_rt_entity(rt_rq, rt_se);
+		requeue_rt_entity(rt_rq, rt_se, head);
 	}
 }
 
 static void yield_task_rt(struct rq *rq)
 {
-	requeue_task_rt(rq, rq->curr);
+	requeue_task_rt(rq, rq->curr, 0);
 }
 
 #ifdef CONFIG_SMP
@@ -606,6 +753,30 @@ static int select_task_rq_rt(struct task_struct *p, int sync)
 	 */
 	return task_cpu(p);
 }
+
+static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
+{
+	cpumask_t mask;
+
+	if (rq->curr->rt.nr_cpus_allowed == 1)
+		return;
+
+	if (p->rt.nr_cpus_allowed != 1
+	    && cpupri_find(&rq->rd->cpupri, p, &mask))
+		return;
+
+	if (!cpupri_find(&rq->rd->cpupri, rq->curr, &mask))
+		return;
+
+	/*
+	 * There appears to be other cpus that can accept
+	 * current and none to run 'p', so lets reschedule
+	 * to try and push current away:
+	 */
+	requeue_task_rt(rq, p, 1);
+	resched_task(rq->curr);
+}
+
 #endif /* CONFIG_SMP */
 
 /*
@@ -613,8 +784,27 @@ static int select_task_rq_rt(struct task_struct *p, int sync)
  */
 static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
 {
-	if (p->prio < rq->curr->prio)
+	if (p->prio < rq->curr->prio) {
 		resched_task(rq->curr);
+		return;
+	}
+
+#ifdef CONFIG_SMP
+	/*
+	 * If:
+	 *
+	 * - the newly woken task is of equal priority to the current task
+	 * - the newly woken task is non-migratable while current is migratable
+	 * - current will be preempted on the next reschedule
+	 *
+	 * we should check to see if current can readily move to a different
+	 * cpu.  If so, we will reschedule to allow the push logic to try
+	 * to move current somewhere else, making room for our non-migratable
+	 * task.
+	 */
+	if (p->prio == rq->curr->prio && !need_resched())
+		check_preempt_equal_prio(rq, p);
+#endif
 }
 
 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
@@ -717,73 +907,6 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
 
 static DEFINE_PER_CPU(cpumask_t, local_cpu_mask);
 
-static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
-{
-	int       lowest_prio = -1;
-	int       lowest_cpu  = -1;
-	int       count       = 0;
-	int       cpu;
-
-	cpus_and(*lowest_mask, task_rq(task)->rd->online, task->cpus_allowed);
-
-	/*
-	 * Scan each rq for the lowest prio.
-	 */
-	for_each_cpu_mask(cpu, *lowest_mask) {
-		struct rq *rq = cpu_rq(cpu);
-
-		/* We look for lowest RT prio or non-rt CPU */
-		if (rq->rt.highest_prio >= MAX_RT_PRIO) {
-			/*
-			 * if we already found a low RT queue
-			 * and now we found this non-rt queue
-			 * clear the mask and set our bit.
-			 * Otherwise just return the queue as is
-			 * and the count==1 will cause the algorithm
-			 * to use the first bit found.
-			 */
-			if (lowest_cpu != -1) {
-				cpus_clear(*lowest_mask);
-				cpu_set(rq->cpu, *lowest_mask);
-			}
-			return 1;
-		}
-
-		/* no locking for now */
-		if ((rq->rt.highest_prio > task->prio)
-		    && (rq->rt.highest_prio >= lowest_prio)) {
-			if (rq->rt.highest_prio > lowest_prio) {
-				/* new low - clear old data */
-				lowest_prio = rq->rt.highest_prio;
-				lowest_cpu = cpu;
-				count = 0;
-			}
-			count++;
-		} else
-			cpu_clear(cpu, *lowest_mask);
-	}
-
-	/*
-	 * Clear out all the set bits that represent
-	 * runqueues that were of higher prio than
-	 * the lowest_prio.
-	 */
-	if (lowest_cpu > 0) {
-		/*
-		 * Perhaps we could add another cpumask op to
-		 * zero out bits. Like cpu_zero_bits(cpumask, nrbits);
-		 * Then that could be optimized to use memset and such.
-		 */
-		for_each_cpu_mask(cpu, *lowest_mask) {
-			if (cpu >= lowest_cpu)
-				break;
-			cpu_clear(cpu, *lowest_mask);
-		}
-	}
-
-	return count;
-}
-
 static inline int pick_optimal_cpu(int this_cpu, cpumask_t *mask)
 {
 	int first;
@@ -805,17 +928,19 @@ static int find_lowest_rq(struct task_struct *task)
 	cpumask_t *lowest_mask = &__get_cpu_var(local_cpu_mask);
 	int this_cpu = smp_processor_id();
 	int cpu      = task_cpu(task);
-	int count    = find_lowest_cpus(task, lowest_mask);
 
-	if (!count)
+	if (task->rt.nr_cpus_allowed == 1)
+		return -1; /* No other targets possible */
+
+	if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
 		return -1; /* No targets found */
 
 	/*
-	 * There is no sense in performing an optimal search if only one
-	 * target is found.
+	 * Only consider CPUs that are usable for migration.
+	 * I guess we might want to change cpupri_find() to ignore those
+	 * in the first place.
 	 */
-	if (count == 1)
-		return first_cpu(*lowest_mask);
+	cpus_and(*lowest_mask, *lowest_mask, cpu_active_map);
 
 	/*
 	 * At this point we have built a mask of cpus representing the
@@ -1003,7 +1128,7 @@ static int pull_rt_task(struct rq *this_rq)
 
 	next = pick_next_task_rt(this_rq);
 
-	for_each_cpu_mask(cpu, this_rq->rd->rto_mask) {
+	for_each_cpu_mask_nr(cpu, this_rq->rd->rto_mask) {
 		if (this_cpu == cpu)
 			continue;
 
@@ -1160,17 +1285,25 @@ static void set_cpus_allowed_rt(struct task_struct *p,
 }
 
 /* Assumes rq->lock is held */
-static void join_domain_rt(struct rq *rq)
+static void rq_online_rt(struct rq *rq)
 {
 	if (rq->rt.overloaded)
 		rt_set_overload(rq);
+
+	__enable_runtime(rq);
+
+	cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio);
 }
 
 /* Assumes rq->lock is held */
-static void leave_domain_rt(struct rq *rq)
+static void rq_offline_rt(struct rq *rq)
 {
 	if (rq->rt.overloaded)
 		rt_clear_overload(rq);
+
+	__disable_runtime(rq);
+
+	cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
 }
 
 /*
@@ -1303,7 +1436,7 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
 	 * on the queue:
 	 */
 	if (p->rt.run_list.prev != p->rt.run_list.next) {
-		requeue_task_rt(rq, p);
+		requeue_task_rt(rq, p, 0);
 		set_tsk_need_resched(p);
 	}
 }
@@ -1333,8 +1466,8 @@ static const struct sched_class rt_sched_class = {
 	.load_balance		= load_balance_rt,
 	.move_one_task		= move_one_task_rt,
 	.set_cpus_allowed       = set_cpus_allowed_rt,
-	.join_domain            = join_domain_rt,
-	.leave_domain           = leave_domain_rt,
+	.rq_online              = rq_online_rt,
+	.rq_offline             = rq_offline_rt,
 	.pre_schedule		= pre_schedule_rt,
 	.post_schedule		= post_schedule_rt,
 	.task_wake_up		= task_wake_up_rt,
@@ -1347,3 +1480,17 @@ static const struct sched_class rt_sched_class = {
 	.prio_changed		= prio_changed_rt,
 	.switched_to		= switched_to_rt,
 };
+
+#ifdef CONFIG_SCHED_DEBUG
+extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
+
+static void print_rt_stats(struct seq_file *m, int cpu)
+{
+	struct rt_rq *rt_rq;
+
+	rcu_read_lock();
+	for_each_leaf_rt_rq(rt_rq, cpu_rq(cpu))
+		print_rt_rq(m, cpu, rt_rq);
+	rcu_read_unlock();
+}
+#endif /* CONFIG_SCHED_DEBUG */