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, 21 insertions, 0 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 566e3bb78ed9..cd73738f0d5f 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1938,6 +1938,25 @@ static void moved_group_fair(struct task_struct *p)
 }
 #endif
 
+unsigned int get_rr_interval_fair(struct task_struct *task)
+{
+        struct sched_entity *se = &task->se;
+        unsigned long flags;
+        struct rq *rq;
+        unsigned int rr_interval = 0;
+
+        /*
+         * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
+         * idle runqueue:
+         */
+        rq = task_rq_lock(task, &flags);
+        if (rq->cfs.load.weight)
+                rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
+        task_rq_unlock(rq, &flags);
+
+        return rr_interval;
+}
+
 /*
  * All the scheduling class methods:
  */
@@ -1966,6 +1985,8 @@ static const struct sched_class fair_sched_class = {
         .prio_changed           = prio_changed_fair,
         .switched_to            = switched_to_fair,
 
+        .get_rr_interval        = get_rr_interval_fair,
+
 #ifdef CONFIG_FAIR_GROUP_SCHED
         .moved_group            = moved_group_fair,
 #endif