Commit-ID: 311e800e16f63d909136a64ed17ca353a160be59
Gitweb: http://git.kernel.org/tip/311e800e16f63d909136a64ed17ca353a160be59
Author: Hillf Danton <dhillf@xxxxxxxxx>
AuthorDate: Thu, 16 Jun 2011 21:55:20 -0400
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Sun, 14 Aug 2011 12:00:48 +0200
sched, rt: Fix rq->rt.pushable_tasks bug in push_rt_task()
Do not call dequeue_pushable_task() when failing to push an eligible
task, as it remains pushable, merely not at this particular moment.
Signed-off-by: Hillf Danton <dhillf@xxxxxxxxx>
Signed-off-by: Mike Galbraith <mgalbraith@xxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Yong Zhang <yong.zhang0@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1306895385.4791.26.camel@xxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/sched_rt.c | 15 ++++++++-------
1 files changed, 8 insertions(+), 7 deletions(-)
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index e2698c0..8e18945 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1394,6 +1394,7 @@ static int push_rt_task(struct rq *rq)
{
struct task_struct *next_task;
struct rq *lowest_rq;
+ int ret = 0;
if (!rq->rt.overloaded)
return 0;
@@ -1426,7 +1427,7 @@ retry:
if (!lowest_rq) {
struct task_struct *task;
/*
- * find lock_lowest_rq releases rq->lock
+ * find_lock_lowest_rq releases rq->lock
* so it is possible that next_task has migrated.
*
* We need to make sure that the task is still on the same
@@ -1436,12 +1437,11 @@ retry:
task = pick_next_pushable_task(rq);
if (task_cpu(next_task) == rq->cpu && task == next_task) {
/*
- * If we get here, the task hasn't moved at all, but
- * it has failed to push. We will not try again,
- * since the other cpus will pull from us when they
- * are ready.
+ * The task hasn't migrated, and is still the next
+ * eligible task, but we failed to find a run-queue
+ * to push it to. Do not retry in this case, since
+ * other cpus will pull from us when ready.
*/
- dequeue_pushable_task(rq, next_task);
goto out;
}
@@ -1460,6 +1460,7 @@ retry:
deactivate_task(rq, next_task, 0);
set_task_cpu(next_task, lowest_rq->cpu);
activate_task(lowest_rq, next_task, 0);
+ ret = 1;
resched_task(lowest_rq->curr);
@@ -1468,7 +1469,7 @@ retry:
out:
put_task_struct(next_task);
- return 1;
+ return ret;
}
static void push_rt_tasks(struct rq *rq)
--
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