linux-kernel - [PATCH] sched/deadline: fix dl entity is still mark yield after replenishing

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Date:	Thu, 20 Nov 2014 19:00:48 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	Juri Lelli <juri.lelli@....com>,
	Kirill Tkhai <ktkhai@...allels.com>,
	linux-kernel@...r.kernel.org,
	Wanpeng Li <wanpeng.li@...ux.intel.com>
Subject: [PATCH] sched/deadline: fix dl entity is still mark yield after replenishing

Yield task semantic for deadline task is get off from the CPU until our next 
instance, we mark the task got to sleep until its current deadline by forcing 
its runtime to zero and update_curr_dl() stops it and the bandwidth timer will 
wake it up and will give it new scheduling parameters.

Bandwidth timer may fail to start in update_curr_dl() and instead replenishing 
the budget immediately, however, dl_yielded of dl_se is cleared when bandwidth 
timer fire, the immediate replenishing miss to reset it. 

This patch fix it by reseting the dl_yielded flag after the immediate replenishing
if fail to start bandwidth timer.

Signed-off-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
---
 kernel/sched/deadline.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 981479a..9d3e31f 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -633,8 +633,11 @@ static void update_curr_dl(struct rq *rq)
 		__dequeue_task_dl(rq, curr, 0);
 		if (likely(start_dl_timer(dl_se, curr->dl.dl_boosted)))
 			dl_se->dl_throttled = 1;
-		else
+		else {
 			enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
+			if (unlikely(dl_se->dl_yielded))
+				dl_se->dl_yielded = 0;
+		}

 		if (!is_leftmost(curr, &rq->dl))
 			resched_curr(rq);
-- 
1.9.1

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