1 files changed, 22 insertions, 4 deletions

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index ee15f5a0d1c1..f4d4b077eba0 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -831,11 +831,14 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
                                 enqueue = 1;
 
                                 /*
-                                 * Force a clock update if the CPU was idle,
-                                 * lest wakeup -> unthrottle time accumulate.
+                                 * When we're idle and a woken (rt) task is
+                                 * throttled check_preempt_curr() will set
+                                 * skip_update and the time between the wakeup
+                                 * and this unthrottle will get accounted as
+                                 * 'runtime'.
                                  */
                                 if (rt_rq->rt_nr_running && rq->curr == rq->idle)
-                                        rq->skip_clock_update = -1;
+                                        rq_clock_skip_update(rq, false);
                         }
                         if (rt_rq->rt_time || rt_rq->rt_nr_running)
                                 idle = 0;
@@ -1337,7 +1340,12 @@ select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
              curr->prio <= p->prio)) {
                 int target = find_lowest_rq(p);
 
-                if (target != -1)
+                /*
+                 * Don't bother moving it if the destination CPU is
+                 * not running a lower priority task.
+                 */
+                if (target != -1 &&
+                    p->prio < cpu_rq(target)->rt.highest_prio.curr)
                         cpu = target;
         }
         rcu_read_unlock();
@@ -1614,6 +1622,16 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
 
                 lowest_rq = cpu_rq(cpu);
 
+                if (lowest_rq->rt.highest_prio.curr <= task->prio) {
+                        /*
+                         * Target rq has tasks of equal or higher priority,
+                         * retrying does not release any lock and is unlikely
+                         * to yield a different result.
+                         */
+                        lowest_rq = NULL;
+                        break;
+                }
+
                 /* if the prio of this runqueue changed, try again */
                 if (double_lock_balance(rq, lowest_rq)) {
                         /*