Re: [PATCH 1/4] block: add mq_ops->queue_rqs hook

[Ming Lei <ming.lei@redhat.com>]

On Tue, Nov 16, 2021 at 08:38:04PM -0700, Jens Axboe wrote:
> If we have a list of requests in our plug list, send it to the driver in
> one go, if possible. The driver must set mq_ops->queue_rqs() to support
> this, if not the usual one-by-one path is used.
> 
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>  block/blk-mq.c         | 17 +++++++++++++++++
>  include/linux/blk-mq.h |  8 ++++++++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 9b4e79e2ac1e..005715206b16 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -2208,6 +2208,19 @@ static void blk_mq_plug_issue_direct(struct blk_plug *plug, bool from_schedule)
>  	int queued = 0;
>  	int errors = 0;
>  
> +	/*
> +	 * Peek first request and see if we have a ->queue_rqs() hook. If we
> +	 * do, we can dispatch the whole plug list in one go. We already know
> +	 * at this point that all requests belong to the same queue, caller
> +	 * must ensure that's the case.
> +	 */
> +	rq = rq_list_peek(&plug->mq_list);
> +	if (rq->q->mq_ops->queue_rqs) {
> +		rq->q->mq_ops->queue_rqs(&plug->mq_list);
> +		if (rq_list_empty(plug->mq_list))
> +			return;
> +	}
> +

Then BLK_MQ_F_TAG_QUEUE_SHARED isn't handled as before for multiple NVMe
NS.


thanks,
Ming