sched: use highest_prio.curr for pull threshold
highest_prio.curr is actually a more accurate way to keep track of
the pull_rt_task() threshold since it is always up to date, even
if the "next" task migrates during double_lock. Therefore, stop
looking at the "next" task object and simply use the highest_prio.curr.
Signed-off-by: Gregory Haskins <ghaskins@novell.com>
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index ad36d72..f8fb3ed 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1207,14 +1207,12 @@
static int pull_rt_task(struct rq *this_rq)
{
int this_cpu = this_rq->cpu, ret = 0, cpu;
- struct task_struct *p, *next;
+ struct task_struct *p;
struct rq *src_rq;
if (likely(!rt_overloaded(this_rq)))
return 0;
- next = pick_next_task_rt(this_rq);
-
for_each_cpu(cpu, this_rq->rd->rto_mask) {
if (this_cpu == cpu)
continue;
@@ -1223,17 +1221,9 @@
/*
* We can potentially drop this_rq's lock in
* double_lock_balance, and another CPU could
- * steal our next task - hence we must cause
- * the caller to recalculate the next task
- * in that case:
+ * alter this_rq
*/
- if (double_lock_balance(this_rq, src_rq)) {
- struct task_struct *old_next = next;
-
- next = pick_next_task_rt(this_rq);
- if (next != old_next)
- ret = 1;
- }
+ double_lock_balance(this_rq, src_rq);
/*
* Are there still pullable RT tasks?
@@ -1247,7 +1237,7 @@
* Do we have an RT task that preempts
* the to-be-scheduled task?
*/
- if (p && (!next || (p->prio < next->prio))) {
+ if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
WARN_ON(p == src_rq->curr);
WARN_ON(!p->se.on_rq);
@@ -1257,12 +1247,9 @@
* This is just that p is wakeing up and hasn't
* had a chance to schedule. We only pull
* p if it is lower in priority than the
- * current task on the run queue or
- * this_rq next task is lower in prio than
- * the current task on that rq.
+ * current task on the run queue
*/
- if (p->prio < src_rq->curr->prio ||
- (next && next->prio < src_rq->curr->prio))
+ if (p->prio < src_rq->curr->prio)
goto skip;
ret = 1;
@@ -1275,13 +1262,7 @@
* case there's an even higher prio task
* in another runqueue. (low likelyhood
* but possible)
- *
- * Update next so that we won't pick a task
- * on another cpu with a priority lower (or equal)
- * than the one we just picked.
*/
- next = p;
-
}
skip:
double_unlock_balance(this_rq, src_rq);