1 files changed, 22 insertions, 18 deletions

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index d10c80ebb67a..bea7d79f7e9c 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -609,7 +609,7 @@ static void update_curr_rt(struct rq *rq)
         if (!task_has_rt_policy(curr))
                 return;
 
-        delta_exec = rq->clock - curr->se.exec_start;
+        delta_exec = rq->clock_task - curr->se.exec_start;
         if (unlikely((s64)delta_exec < 0))
                 delta_exec = 0;
 
@@ -618,7 +618,7 @@ static void update_curr_rt(struct rq *rq)
         curr->se.sum_exec_runtime += delta_exec;
         account_group_exec_runtime(curr, delta_exec);
 
-        curr->se.exec_start = rq->clock;
+        curr->se.exec_start = rq->clock_task;
         cpuacct_charge(curr, delta_exec);
 
         sched_rt_avg_update(rq, delta_exec);
@@ -960,18 +960,19 @@ select_task_rq_rt(struct rq *rq, struct task_struct *p, int sd_flag, int flags)
          * runqueue. Otherwise simply start this RT task
          * on its current runqueue.
          *
-         * We want to avoid overloading runqueues. Even if
-         * the RT task is of higher priority than the current RT task.
-         * RT tasks behave differently than other tasks. If
-         * one gets preempted, we try to push it off to another queue.
-         * So trying to keep a preempting RT task on the same
-         * cache hot CPU will force the running RT task to
-         * a cold CPU. So we waste all the cache for the lower
-         * RT task in hopes of saving some of a RT task
-         * that is just being woken and probably will have
-         * cold cache anyway.
+         * We want to avoid overloading runqueues. If the woken
+         * task is a higher priority, then it will stay on this CPU
+         * and the lower prio task should be moved to another CPU.
+         * Even though this will probably make the lower prio task
+         * lose its cache, we do not want to bounce a higher task
+         * around just because it gave up its CPU, perhaps for a
+         * lock?
+         *
+         * For equal prio tasks, we just let the scheduler sort it out.
          */
         if (unlikely(rt_task(rq->curr)) &&
+            (rq->curr->rt.nr_cpus_allowed < 2 ||
+             rq->curr->prio < p->prio) &&
             (p->rt.nr_cpus_allowed > 1)) {
                 int cpu = find_lowest_rq(p);
 
@@ -1074,7 +1075,7 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq)
         } while (rt_rq);
 
         p = rt_task_of(rt_se);
-        p->se.exec_start = rq->clock;
+        p->se.exec_start = rq->clock_task;
 
         return p;
 }
@@ -1139,7 +1140,7 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
         for_each_leaf_rt_rq(rt_rq, rq) {
                 array = &rt_rq->active;
                 idx = sched_find_first_bit(array->bitmap);
- next_idx:
+next_idx:
                 if (idx >= MAX_RT_PRIO)
                         continue;
                 if (next && next->prio < idx)
@@ -1315,7 +1316,7 @@ static int push_rt_task(struct rq *rq)
         if (!next_task)
                 return 0;
 
- retry:
+retry:
         if (unlikely(next_task == rq->curr)) {
                 WARN_ON(1);
                 return 0;
@@ -1463,7 +1464,7 @@ static int pull_rt_task(struct rq *this_rq)
                          * but possible)
                          */
                 }
- skip:
+skip:
                 double_unlock_balance(this_rq, src_rq);
         }
 
@@ -1491,7 +1492,10 @@ static void task_woken_rt(struct rq *rq, struct task_struct *p)
         if (!task_running(rq, p) &&
             !test_tsk_need_resched(rq->curr) &&
             has_pushable_tasks(rq) &&
-            p->rt.nr_cpus_allowed > 1)
+            p->rt.nr_cpus_allowed > 1 &&
+            rt_task(rq->curr) &&
+            (rq->curr->rt.nr_cpus_allowed < 2 ||
+             rq->curr->prio < p->prio))
                 push_rt_tasks(rq);
 }
 
@@ -1709,7 +1713,7 @@ static void set_curr_task_rt(struct rq *rq)
 {
         struct task_struct *p = rq->curr;
 
-        p->se.exec_start = rq->clock;
+        p->se.exec_start = rq->clock_task;
 
         /* The running task is never eligible for pushing */
         dequeue_pushable_task(rq, p);