diff options
| -rw-r--r-- | kernel/sched_rt.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index 87d7b3ff3861..9becc3710b60 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -160,11 +160,23 @@ static int select_task_rq_rt(struct task_struct *p, int sync) struct rq *rq = task_rq(p); /* - * If the task will not preempt the RQ, try to find a better RQ - * before we even activate the task + * If the current task is an RT task, then + * try to see if we can wake this RT task up on another + * 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. */ - if ((p->prio >= rq->rt.highest_prio) - && (p->nr_cpus_allowed > 1)) { + if (unlikely(rt_task(rq->curr))) { int cpu = find_lowest_rq(p); return (cpu == -1) ? task_cpu(p) : cpu; |