sched: Account rr tasks

In order to evaluate the scheduler tick dependency without probing
context switches, we need to know how much SCHED_RR and SCHED_FIFO tasks
are enqueued as those policies don't have the same preemption
requirements.

To prepare for that, let's account SCHED_RR tasks, we'll be able to
deduce SCHED_FIFO tasks as well from it and the total RT tasks in the
runqueue.

Reviewed-by: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 8ec86ab..3f1fcff 100644 (file)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1141,6 +1141,20 @@ unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
                return 1;
 }
 
+static inline
+unsigned int rt_se_rr_nr_running(struct sched_rt_entity *rt_se)
+{
+       struct rt_rq *group_rq = group_rt_rq(rt_se);
+       struct task_struct *tsk;
+
+       if (group_rq)
+               return group_rq->rr_nr_running;
+
+       tsk = rt_task_of(rt_se);
+
+       return (tsk->policy == SCHED_RR) ? 1 : 0;
+}
+
 static inline
 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 {
@@ -1148,6 +1162,7 @@ void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 
        WARN_ON(!rt_prio(prio));
        rt_rq->rt_nr_running += rt_se_nr_running(rt_se);
+       rt_rq->rr_nr_running += rt_se_rr_nr_running(rt_se);
 
        inc_rt_prio(rt_rq, prio);
        inc_rt_migration(rt_se, rt_rq);
@@ -1160,6 +1175,7 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
        WARN_ON(!rt_prio(rt_se_prio(rt_se)));
        WARN_ON(!rt_rq->rt_nr_running);
        rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);
+       rt_rq->rr_nr_running -= rt_se_rr_nr_running(rt_se);
 
        dec_rt_prio(rt_rq, rt_se_prio(rt_se));
        dec_rt_migration(rt_se, rt_rq);

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 10f1637..f0abfce 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -450,6 +450,7 @@ static inline int rt_bandwidth_enabled(void)
 struct rt_rq {
        struct rt_prio_array active;
        unsigned int rt_nr_running;
+       unsigned int rr_nr_running;
 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
        struct {
                int curr; /* highest queued rt task prio */