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 <[EMAIL PROTECTED]>
--- cfq/block/cfq-iosched.c~ 2007-08-09 19:59:26.000000000 +0400
+++ cfq/block/cfq-iosched.c 2007-11-06 22:39:08.000000000 +0300
@@ -2122,6 +2122,7 @@ static void *cfq_init_queue(struct reque
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];
-
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