[RFC][PATCH RT 3/4 v2] sched/rt: Initiate a pull when the priority of a task is lowered

[Steven Rostedt]

If a task lowers its priority (say by losing priority inheritance)
if a higher priority task is waiting on another CPU, initiate a pull.

Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>

Index: linux-rt.git/kernel/sched/rt.c
===================================================================
--- linux-rt.git.orig/kernel/sched/rt.c
+++ linux-rt.git/kernel/sched/rt.c
@@ -997,6 +997,8 @@ inc_rt_prio(struct rt_rq *rt_rq, int pri
 	inc_rt_prio_smp(rt_rq, prio, prev_prio);
 }
 
+static int pull_rt_task(struct rq *this_rq);
+
 static void
 dec_rt_prio(struct rt_rq *rt_rq, int prio)
 {
@@ -1021,6 +1023,10 @@ dec_rt_prio(struct rt_rq *rt_rq, int pri
 		rt_rq->highest_prio.curr = MAX_RT_PRIO;
 
 	dec_rt_prio_smp(rt_rq, prio, prev_prio);
+
+	/* Try to pull RT tasks here if we lower this rq's prio */
+	if (prev_prio < rt_rq->highest_prio.curr)
+		pull_rt_task(rq_of_rt_rq(rt_rq));
 }
 
 #else

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