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cfq: fix IOPRIO_CLASS_IDLE delays 

After the fresh boot:

	ionice -c3 -p $$
	echo cfq >> /sys/block/XXX/queue/scheduler
	dd if=/dev/XXX of=/dev/null bs=512 count=1

Now dd hangs in D state and the queue is completely stalled for approximately
INITIAL_JIFFIES + CFQ_IDLE_GRACE jiffies. This is because cfq_init_queue()
forgets to initialize cfq_data->last_end_request.

(I guess this patch is not complete, overflow is still possible)

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Oleg Nesterov 2007-11-07 09:46:13 +01:00 committed by Jens Axboe
parent 2389d1ef17
commit b70c864d3c
1 changed files with 1 additions and 0 deletions
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1
block/cfq-iosched.c
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@ -2126,6 +2126,7 @@ static void *cfq_init_queue(struct request_queue *q)
INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
cfqd->last_end_request = jiffies;
cfqd->cfq_quantum = cfq_quantum;
cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];