Re: [PATCH]sched/rt: Do not try to push tasks if pinned task switches to RT

[Steven Rostedt]

Peter,

I'm going through my inbox (over a year old), and found this patch from
Kirill. It looks fine to me. You can apply it with my

  Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>

-- Steve

[PATCH]sched/rt: Do not try to push tasks if pinned task switches to RT

Just switched pinned task is not able to be pushed. If the rq had had
several RT tasks before they have already been considered as candidates
to be pushed (or pulled).

Signed-off-by: Kirill V Tkhai <tkhai@xxxxxxxxx>
CC: Steven Rostedt <rostedt@xxxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CC: linux-rt-users <linux-rt-users@xxxxxxxxxxxxxxx>
---
 kernel/sched/rt.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 4e8f0f4..5aab032 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1925,9 +1925,9 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
 	 */
 	if (p->on_rq && rq->curr != p) {
 #ifdef CONFIG_SMP
-		if (rq->rt.overloaded && push_rt_task(rq) &&
+		if (p->nr_cpus_allowed > 1 && rq->rt.overloaded &&
 		    /* Don't resched if we changed runqueues */
-		    rq != task_rq(p))
+		    push_rt_task(rq) && rq != task_rq(p))
 			check_resched = 0;
 #endif /* CONFIG_SMP */
 		if (check_resched && p->prio < rq->curr->prio)
--
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