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Diffstat (limited to 'kernel/sched_rt.c')
-rw-r--r--kernel/sched_rt.c75
1 files changed, 68 insertions, 7 deletions
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 3432d57..fefed39 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -458,7 +458,13 @@ static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
if (group_rq && rt_rq_throttled(group_rq))
return;
- list_add_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
+ if (rt_se->nr_cpus_allowed == 1)
+ list_add_tail(&rt_se->run_list,
+ array->xqueue + rt_se_prio(rt_se));
+ else
+ list_add_tail(&rt_se->run_list,
+ array->squeue + rt_se_prio(rt_se));
+
__set_bit(rt_se_prio(rt_se), array->bitmap);
inc_rt_tasks(rt_se, rt_rq);
@@ -470,7 +476,8 @@ static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
struct rt_prio_array *array = &rt_rq->active;
list_del_init(&rt_se->run_list);
- if (list_empty(array->queue + rt_se_prio(rt_se)))
+ if (list_empty(array->squeue + rt_se_prio(rt_se))
+ && list_empty(array->xqueue + rt_se_prio(rt_se)))
__clear_bit(rt_se_prio(rt_se), array->bitmap);
dec_rt_tasks(rt_se, rt_rq);
@@ -537,13 +544,19 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
/*
* Put task to the end of the run list without the overhead of dequeue
* followed by enqueue.
+ *
+ * Note: We always enqueue the task to the shared-queue, regardless of its
+ * previous position w.r.t. exclusive vs shared. This is so that exclusive RR
+ * tasks fairly round-robin with all tasks on the runqueue, not just other
+ * exclusive tasks.
*/
static
void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
{
struct rt_prio_array *array = &rt_rq->active;
- list_move_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
+ list_del_init(&rt_se->run_list);
+ list_add_tail(&rt_se->run_list, array->squeue + rt_se_prio(rt_se));
}
static void requeue_task_rt(struct rq *rq, struct task_struct *p)
@@ -601,13 +614,46 @@ static int select_task_rq_rt(struct task_struct *p, int sync)
}
#endif /* CONFIG_SMP */
+static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
+ struct rt_rq *rt_rq);
+
/*
* Preempt the current task with a newly woken task if needed:
*/
static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
{
- if (p->prio < rq->curr->prio)
+ if (p->prio < rq->curr->prio) {
resched_task(rq->curr);
+ return;
+ }
+
+#ifdef CONFIG_SMP
+ /*
+ * If:
+ *
+ * - the newly woken task is of equal priority to the current task
+ * - the newly woken task is non-migratable while current is migratable
+ * - current will be preempted on the next reschedule
+ *
+ * we should check to see if current can readily move to a different
+ * cpu. If so, we will reschedule to allow the push logic to try
+ * to move current somewhere else, making room for our non-migratable
+ * task.
+ */
+ if((p->prio == rq->curr->prio)
+ && p->rt.nr_cpus_allowed == 1
+ && rq->curr->rt.nr_cpus_allowed != 1
+ && pick_next_rt_entity(rq, &rq->rt) != &rq->curr->rt) {
+ cpumask_t mask;
+
+ if (cpupri_find(&rq->rd->cpupri, rq->curr, &mask))
+ /*
+ * There appears to be other cpus that can accept
+ * current, so lets reschedule to try and push it away
+ */
+ resched_task(rq->curr);
+ }
+#endif
}
static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
@@ -621,8 +667,15 @@ static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
idx = sched_find_first_bit(array->bitmap);
BUG_ON(idx >= MAX_RT_PRIO);
- queue = array->queue + idx;
- next = list_entry(queue->next, struct sched_rt_entity, run_list);
+ queue = array->xqueue + idx;
+ if (!list_empty(queue))
+ next = list_entry(queue->next, struct sched_rt_entity,
+ run_list);
+ else {
+ queue = array->squeue + idx;
+ next = list_entry(queue->next, struct sched_rt_entity,
+ run_list);
+ }
return next;
}
@@ -692,7 +745,7 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
continue;
if (next && next->prio < idx)
continue;
- list_for_each_entry(rt_se, array->queue + idx, run_list) {
+ list_for_each_entry(rt_se, array->squeue + idx, run_list) {
struct task_struct *p = rt_task_of(rt_se);
if (pick_rt_task(rq, p, cpu)) {
next = p;
@@ -1146,6 +1199,14 @@ static void set_cpus_allowed_rt(struct task_struct *p,
}
update_rt_migration(rq);
+
+ if (unlikely(weight == 1 || p->rt.nr_cpus_allowed == 1))
+ /*
+ * If either the new or old weight is a "1", we need
+ * to requeue to properly move between shared and
+ * exclusive queues.
+ */
+ requeue_task_rt(rq, p);
}
p->cpus_allowed = *new_mask;