From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.
===============
commit fd7a4bed183523275279c9addbf42fce550c2e90 upstream.
Remove the direct {push,pull} balancing operations from
switched_{from,to}_rt() / prio_changed_rt() and use the balance
callback queue.
Again, err on the side of too many reschedules; since too few is a
hard bug while too many is just annoying.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: ktkhai@xxxxxxxxxxxxx
Cc: rostedt@xxxxxxxxxxx
Cc: juri.lelli@xxxxxxxxx
Cc: pang.xunlei@xxxxxxxxxx
Cc: oleg@xxxxxxxxxx
Cc: wanpeng.li@xxxxxxxxxxxxxxx
Cc: umgwanakikbuti@xxxxxxxxx
Link: http://lkml.kernel.org/r/20150611124742.766832367@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
kernel/sched/rt.c | 35 +++++++++++++++++++----------------
1 file changed, 19 insertions(+), 16 deletions(-)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 85a09baa8f9f..10edf9d2a8b7 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -315,16 +315,23 @@ static inline int has_pushable_tasks(struct rq *rq)
return !plist_head_empty(&rq->rt.pushable_tasks);
}
-static DEFINE_PER_CPU(struct callback_head, rt_balance_head);
+static DEFINE_PER_CPU(struct callback_head, rt_push_head);
+static DEFINE_PER_CPU(struct callback_head, rt_pull_head);
static void push_rt_tasks(struct rq *);
+static void pull_rt_task(struct rq *);
static inline void queue_push_tasks(struct rq *rq)
{
if (!has_pushable_tasks(rq))
return;
- queue_balance_callback(rq, &per_cpu(rt_balance_head, rq->cpu), push_rt_tasks);
+ queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
+}
+
+static inline void queue_pull_task(struct rq *rq)
+{
+ queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
}
static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
@@ -1832,7 +1839,7 @@ static void switched_from_rt(struct rq *rq, struct task_struct *p)
if (!p->on_rq || rq->rt.rt_nr_running)
return;
- pull_rt_task(rq);
+ queue_pull_task(rq);
}
void init_sched_rt_class(void)
@@ -1853,8 +1860,6 @@ void init_sched_rt_class(void)
*/
static void switched_to_rt(struct rq *rq, struct task_struct *p)
{
- int check_resched = 1;
-
/*
* If we are already running, then there's nothing
* that needs to be done. But if we are not running
@@ -1864,13 +1869,12 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
*/
if (p->on_rq && rq->curr != p) {
#ifdef CONFIG_SMP
- if (rq->rt.overloaded && push_rt_task(rq) &&
- /* Don't resched if we changed runqueues */
- rq != task_rq(p))
- check_resched = 0;
-#endif /* CONFIG_SMP */
- if (check_resched && p->prio < rq->curr->prio)
+ if (rq->rt.overloaded)
+ queue_push_tasks(rq);
+#else
+ if (p->prio < rq->curr->prio)
resched_task(rq->curr);
+#endif /* CONFIG_SMP */
}
}
@@ -1891,14 +1895,13 @@ prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
* may need to pull tasks to this runqueue.
*/
if (oldprio < p->prio)
- pull_rt_task(rq);
+ queue_pull_task(rq);
+
/*
* If there's a higher priority task waiting to run
- * then reschedule. Note, the above pull_rt_task
- * can release the rq lock and p could migrate.
- * Only reschedule if p is still on the same runqueue.
+ * then reschedule.
*/
- if (p->prio > rq->rt.highest_prio.curr && rq->curr == p)
+ if (p->prio > rq->rt.highest_prio.curr)
resched_task(p);
#else
/* For UP simply resched on drop of prio */
--
2.7.2
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html