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-rw-r--r--kernel/sched_rt.c22
1 files changed, 12 insertions, 10 deletions
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index d10c80ebb67a..6a02b38ab653 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -960,18 +960,18 @@ 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->prio < p->prio &&
(p->rt.nr_cpus_allowed > 1)) {
int cpu = find_lowest_rq(p);
@@ -1491,6 +1491,8 @@ 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) &&
+ rt_task(rq->curr) &&
+ rq->curr->prio < p->prio &&
p->rt.nr_cpus_allowed > 1)
push_rt_tasks(rq);
}