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 <rostedt@goodmis.org>
---

 kernel/sched.c    |    2 ++

 kernel/sched_rt.c |   18 ++++++++++++++++++

 2 files changed, 20 insertions(+)
Index: linux-test.git/kernel/sched.c

===================================================================

--- linux-test.git.orig/kernel/sched.c	2007-10-19 12:32:39.000000000 -0400

+++ linux-test.git/kernel/sched.c	2007-10-19 12:33:09.000000000 -0400

@@ -300,6 +300,8 @@ struct rq {

 	 */

 	unsigned long nr_uninterruptible;
+	unsigned long rt_nr_running;

+

 	struct task_struct *curr, *idle;

 	unsigned long next_balance;

 	struct mm_struct *prev_mm;

Index: linux-test.git/kernel/sched_rt.c

===================================================================

--- linux-test.git.orig/kernel/sched_rt.c	2007-10-19 12:31:08.000000000 -0400

+++ linux-test.git/kernel/sched_rt.c	2007-10-19 12:33:09.000000000 -0400

@@ -25,12 +25,28 @@ static void update_curr_rt(struct rq *rq

 	curr->se.exec_start = rq->clock;

 }
+static inline void inc_rt_tasks(struct task_struct *p, struct rq *rq)

+{

+	if (rt_task(p))

+		rq->rt_nr_running++;

+}

+

+static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq)

+{

+	if (rt_task(p)) {

+		WARN_ON(!rq->rt_nr_running);

+		rq->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;
 	list_add_tail(&p->run_list, array->queue + p->prio);

 	__set_bit(p->prio, array->bitmap);

+

+	inc_rt_tasks(p, rq);

 }
 /*

@@ -42,6 +58,8 @@ static void dequeue_task_rt(struct rq *r
 	update_curr_rt(rq);
+	dec_rt_tasks(p, rq);

+

 	list_del(&p->run_list);

 	if (list_empty(array->queue + p->prio))

 		__clear_bit(p->prio, array->bitmap);
--

-

why do you need the rt_task(p) check in {inc,dec}_rt_tasks() ?
{enqueue,dequeue}_task_rt() seem to be the only callers and they will

crash (or corrupt memory) anyway in the case of ! rt_task(p) (sure,

this case would mean something is broken somewhere wrt sched_class

handling).
--

Best regards,

Dmitry Adamushko

-

Hi Dmitry,
--
Maybe. I didn't really look too hard to where to put it. Currently, in the

-rt patch, it is located in struct rq, so I just did the same. I may be
Exactly, I was just being safe. We could add a WARN_ON(!rt_task) there.
-- Steve
-