1 files changed, 15 insertions, 6 deletions

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index a8a08030a8f7..1842c3e33476 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -18,6 +18,8 @@
 #include "sched.h"
 #include "pelt.h"
 
+#include <litmus/litmus.h>
+
 struct dl_bandwidth def_dl_bandwidth;
 
 static inline struct task_struct *dl_task_of(struct sched_dl_entity *dl_se)
@@ -1049,17 +1051,21 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
 #endif
 
         enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
-        if (dl_task(rq->curr))
+        if (dl_task(rq->curr)) {
                 check_preempt_curr_dl(rq, p, 0);
-        else
+        } else if (!is_realtime(rq->curr)) {
                 resched_curr(rq);
+        }
 
 #ifdef CONFIG_SMP
         /*
          * Queueing this task back might have overloaded rq, check if we need
          * to kick someone away.
+         *
+         * LITMUS note: Don't incur this overhead if we are running a LITMUS
+         * task.
          */
-        if (has_pushable_dl_tasks(rq)) {
+        if (has_pushable_dl_tasks(rq) && (!is_realtime(rq->curr))) {
                 /*
                  * Nothing relies on rq->lock after this, so its safe to drop
                  * rq->lock.
@@ -2357,9 +2363,13 @@ static void switched_from_dl(struct rq *rq, struct task_struct *p)
          * Since this might be the only -deadline task on the rq,
          * this is the right place to try to pull some other one
          * from an overloaded CPU, if any.
+         *
+         * LITMUS note: also don't pull a task when we're running LITMUS tasks.
          */
-        if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
+        if (!task_on_rq_queued(p) || rq->dl.dl_nr_running ||
+                is_realtime(rq->curr)) {
                 return;
+        }
 
         deadline_queue_pull_task(rq);
 }
@@ -2374,9 +2384,8 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
                 put_task_struct(p);
 
         /* If p is not queued we will update its parameters at next wakeup. */
-        if (!task_on_rq_queued(p)) {
+        if (!task_on_rq_queued(p) || is_realtime(rq->curr)) {
                 add_rq_bw(&p->dl, &rq->dl);
-
                 return;
         }