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* [PATCH for 4.1-rc] dm: run queue on re-queue
@ 2015-05-26  8:25 Junichi Nomura
  2015-05-26 13:09 ` Mike Snitzer
  0 siblings, 1 reply; 2+ messages in thread
From: Junichi Nomura @ 2015-05-26  8:25 UTC (permalink / raw)
  To: device-mapper development; +Cc: Jens Axboe, Mike Snitzer

Without kicking queue, requeued request may stay forever in
the queue if there are no other I/O activities to the device.

The original error had been in v2.6.39 with commit 7eaceaccab5f
("block: remove per-queue plugging"), which replaced conditional
plugging by periodic runqueue.

Commit 9d1deb83d489 in v4.1-rc1 removed the periodic runqueue
and the problem started to manifest.

Fixes: 9d1deb83d489 ("dm: don't schedule delayed run of the queue if nothing to do")
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index a930b72..0bf79a0 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1164,6 +1164,7 @@ static void old_requeue_request(struct request *rq)
 
 	spin_lock_irqsave(q->queue_lock, flags);
 	blk_requeue_request(q, rq);
+	blk_run_queue_async(q);
 	spin_unlock_irqrestore(q->queue_lock, flags);
 }
 

^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH for 4.1-rc] dm: run queue on re-queue
  2015-05-26  8:25 [PATCH for 4.1-rc] dm: run queue on re-queue Junichi Nomura
@ 2015-05-26 13:09 ` Mike Snitzer
  0 siblings, 0 replies; 2+ messages in thread
From: Mike Snitzer @ 2015-05-26 13:09 UTC (permalink / raw)
  To: Junichi Nomura; +Cc: Jens Axboe, device-mapper development

On Tue, May 26 2015 at  4:25P -0400,
Junichi Nomura <j-nomura@ce.jp.nec.com> wrote:

> Without kicking queue, requeued request may stay forever in
> the queue if there are no other I/O activities to the device.
> 
> The original error had been in v2.6.39 with commit 7eaceaccab5f
> ("block: remove per-queue plugging"), which replaced conditional
> plugging by periodic runqueue.
> 
> Commit 9d1deb83d489 in v4.1-rc1 removed the periodic runqueue
> and the problem started to manifest.
> 
> Fixes: 9d1deb83d489 ("dm: don't schedule delayed run of the queue if nothing to do")
> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
> 
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index a930b72..0bf79a0 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1164,6 +1164,7 @@ static void old_requeue_request(struct request *rq)
>  
>  	spin_lock_irqsave(q->queue_lock, flags);
>  	blk_requeue_request(q, rq);
> +	blk_run_queue_async(q);
>  	spin_unlock_irqrestore(q->queue_lock, flags);
>  }

Thanks Junichi.  The new blk-mq path did kick the queue, but obviously
the old request_fn path didn't.  I'll get this queued for 4.1.

Mike

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2015-05-26 13:09 UTC | newest]

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2015-05-26  8:25 [PATCH for 4.1-rc] dm: run queue on re-queue Junichi Nomura
2015-05-26 13:09 ` Mike Snitzer

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