Re: [PATCH v2] xen/blkfront: convert to blk-mq APIs
From: Jens Axboe
Date: Sat Jul 11 2015 - 14:15:50 EST
On 07/11/2015 07:30 AM, Bob Liu wrote:
Note: This patch is based on original work of Arianna's internship for
GNOME's Outreach Program for Women.
Great to see this finally get prepped to go in!
Only one hardware queue is used now, so there is no performance change.
I would hope that the blk-mq path, even with one queue, is a perf win
over the old interface. So I'm not sure that is correct. But the bigger
win will be with more queues, of course.
The legacy non-mq code is deleted completely which is the same as other
drivers like virtio, mtip, and nvme.
Also dropped one unnecessary holding of info->io_lock when calling
blk_mq_stop_hw_queues().
Changes in v2:
- Reorganized blk_mq_queue_rq()
- Restored most io_locks in place
Looks good to me. The most common error case is the busy-out not
stopping queues, or not restarting them at completion. But that all
looks fine.
I would, however, rename blk_mq_queue_rq(). It sounds like a core
function. blkif_queue_rq() would be more appropriate.
Signed-off-by: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
Acked-by: Jens Axboe <axboe@xxxxxx>
--
Jens Axboe
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