sched: Simplify sys_sched_rr_get_interval() system call

By removing the need for it to know details of scheduling classes.

This allows PlugSched to define orthogonal scheduling classes.

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <06d1b89ee15a0eef82d7.1253496713@mudlark.pw.nest>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 13 insertions, 0 deletions

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 13de7126a6ab..a4d790cddb19 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1734,6 +1734,17 @@ static void set_curr_task_rt(struct rq *rq)
         dequeue_pushable_task(rq, p);
 }
 
+unsigned int get_rr_interval_rt(struct task_struct *task)
+{
+        /*
+         * Time slice is 0 for SCHED_FIFO tasks
+         */
+        if (task->policy == SCHED_RR)
+                return DEF_TIMESLICE;
+        else
+                return 0;
+}
+
 static const struct sched_class rt_sched_class = {
         .next                   = &fair_sched_class,
         .enqueue_task           = enqueue_task_rt,
@@ -1762,6 +1773,8 @@ static const struct sched_class rt_sched_class = {
         .set_curr_task          = set_curr_task_rt,
         .task_tick              = task_tick_rt,
 
+        .get_rr_interval        = get_rr_interval_rt,
+
         .prio_changed           = prio_changed_rt,
         .switched_to            = switched_to_rt,
 };