sched: wake-balance fixes
We have logic to detect whether the system has migratable tasks, but we are
not using it when deciding whether to push tasks away. So we add support
for considering this new information.
Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index 3344ba7..c591abd 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -346,6 +346,7 @@
unsigned long rt_nr_migratory;
/* highest queued rt task prio */
int highest_prio;
+ int overloaded;
};
/*
@@ -6770,6 +6771,7 @@
rq->migration_thread = NULL;
INIT_LIST_HEAD(&rq->migration_queue);
rq->rt.highest_prio = MAX_RT_PRIO;
+ rq->rt.overloaded = 0;
#endif
atomic_set(&rq->nr_iowait, 0);
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index a9d7d44..87d7b3f 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -16,6 +16,7 @@
}
static inline void rt_set_overload(struct rq *rq)
{
+ rq->rt.overloaded = 1;
cpu_set(rq->cpu, rt_overload_mask);
/*
* Make sure the mask is visible before we set
@@ -32,6 +33,7 @@
/* the order here really doesn't matter */
atomic_dec(&rto_count);
cpu_clear(rq->cpu, rt_overload_mask);
+ rq->rt.overloaded = 0;
}
static void update_rt_migration(struct rq *rq)
@@ -448,6 +450,9 @@
assert_spin_locked(&rq->lock);
+ if (!rq->rt.overloaded)
+ return 0;
+
next_task = pick_next_highest_task_rt(rq, -1);
if (!next_task)
return 0;
@@ -675,7 +680,7 @@
* the lock was owned by prev, we need to release it
* first via finish_lock_switch and then reaquire it here.
*/
- if (unlikely(rq->rt.rt_nr_running > 1)) {
+ if (unlikely(rq->rt.overloaded)) {
spin_lock_irq(&rq->lock);
push_rt_tasks(rq);
spin_unlock_irq(&rq->lock);
@@ -687,7 +692,8 @@
{
if (unlikely(rt_task(p)) &&
!task_running(rq, p) &&
- (p->prio >= rq->curr->prio))
+ (p->prio >= rq->rt.highest_prio) &&
+ rq->rt.overloaded)
push_rt_tasks(rq);
}