sched: count # of queued RT tasks

This patch adds accounting to keep track of the number of RT tasks running
on a runqueue. This information will be used in later patches.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 18 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 5b3d46574eeb..9dd8d121eea6 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -342,6 +342,7 @@ struct rt_rq {
         struct rt_prio_array active;
         int rt_load_balance_idx;
         struct list_head *rt_load_balance_head, *rt_load_balance_curr;
+        unsigned long rt_nr_running;
 };
 
 /*
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index cefcd5105146..e3d2ca8832af 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -26,6 +26,19 @@ static void update_curr_rt(struct rq *rq)
         cpuacct_charge(curr, delta_exec);
 }
 
+static inline void inc_rt_tasks(struct task_struct *p, struct rq *rq)
+{
+        WARN_ON(!rt_task(p));
+        rq->rt.rt_nr_running++;
+}
+
+static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq)
+{
+        WARN_ON(!rt_task(p));
+        WARN_ON(!rq->rt.rt_nr_running);
+        rq->rt.rt_nr_running--;
+}
+
 static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
 {
         struct rt_prio_array *array = &rq->rt.active;
@@ -33,6 +46,8 @@ static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
         list_add_tail(&p->run_list, array->queue + p->prio);
         __set_bit(p->prio, array->bitmap);
         inc_cpu_load(rq, p->se.load.weight);
+
+        inc_rt_tasks(p, rq);
 }
 
 /*
@@ -48,6 +63,8 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
         if (list_empty(array->queue + p->prio))
                 __clear_bit(p->prio, array->bitmap);
         dec_cpu_load(rq, p->se.load.weight);
+
+        dec_rt_tasks(p, rq);
 }
 
 /*