sched: de-SCHED_OTHER-ize the RT path

The current wake-up code path tries to determine if it can optimize the
wake-up to "this_cpu" by computing load calculations.  The problem is that
these calculations are only relevant to SCHED_OTHER tasks where load is king.
For RT tasks, priority is king.  So the load calculation is completely wasted
bandwidth.

Therefore, we create a new sched_class interface to help with
pre-wakeup routing decisions and move the load calculation as a function
of CFS task's class.

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

1 files changed, 10 insertions, 0 deletions

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index b788e35ffd3f..5de1aebdbd1b 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -150,6 +150,13 @@ yield_task_rt(struct rq *rq)
         requeue_task_rt(rq, rq->curr);
 }
 
+#ifdef CONFIG_SMP
+static int select_task_rq_rt(struct task_struct *p, int sync)
+{
+        return task_cpu(p);
+}
+#endif /* CONFIG_SMP */
+
 /*
  * Preempt the current task with a newly woken task if needed:
  */
@@ -667,6 +674,9 @@ const struct sched_class rt_sched_class = {
         .enqueue_task           = enqueue_task_rt,
         .dequeue_task           = dequeue_task_rt,
         .yield_task             = yield_task_rt,
+#ifdef CONFIG_SMP
+        .select_task_rq         = select_task_rq_rt,
+#endif /* CONFIG_SMP */
 
         .check_preempt_curr     = check_preempt_curr_rt,