On 09/14/2016 06:29 PM, Mike Snitzer wrote:
> Otherwise blk-mq will immediately dispatch requests that are requeued
> via a BLK_MQ_RQ_QUEUE_BUSY return from blk_mq_ops .queue_rq.
>
> Delayed requeue is implemented using blk_mq_delay_kick_requeue_list()
> with a delay of 5 secs. In the context of DM multipath (all paths down)
> it doesn't make any sense to requeue more quickly.
>
> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
> ---
> drivers/md/dm-rq.c | 32 ++++++++++++++++++--------------
> include/linux/device-mapper.h | 1 +
> 2 files changed, 19 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
> index 0d301d5..9eebc8d 100644
> --- a/drivers/md/dm-rq.c
> +++ b/drivers/md/dm-rq.c
[..]
> @@ -671,7 +673,10 @@ static int map_request(struct dm_rq_target_io *tio, struct request *rq,
> break;
> case DM_MAPIO_REQUEUE:
> /* The target wants to requeue the I/O */
> - dm_requeue_original_request(md, tio->orig);
> + break;
> + case DM_MAPIO_DELAY_REQUEUE:
> + /* The target wants to requeue the I/O after a delay */
> + dm_requeue_original_request(md, tio->orig, true);
> break;
> default:
> if (r > 0) {
Hmm? What happened here?
Don't we need to requeue the request for DM_MAPIO_REQUEUE?
> @@ -681,10 +686,9 @@ static int map_request(struct dm_rq_target_io *tio, struct request *rq,
>
> /* The target wants to complete the I/O */
> dm_kill_unmapped_request(rq, r);
> - return r;
> }
>
> - return 0;
> + return r;
> }
>
> static void dm_start_request(struct mapped_device *md, struct request *orig)
[ .. ]
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
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SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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