[PATCH 1/6] nvme-pci: reverse request order in nvme_queue_rqs

[Keith Busch]

On Wed, Nov 13, 2024 at 04:20:41PM +0100, Christoph Hellwig wrote:
> blk_mq_flush_plug_list submits requests in the reverse order that they
> were submitted, which leads to a rather suboptimal I/O pattern especially
> in rotational devices.  Fix this by rewriting nvme_queue_rqs so that it
> always pops the requests from the passed in request list, and then adds
> them to the head of a local submit list.  This actually simplifies the
> code a bit as it removes the complicated list splicing, at the cost of
> extra updates of the rq_next pointer.  As that should be cache hot
> anyway it should be an easy price to pay.

Looks good.

Reviewed-by: Keith Busch <kbusch at kernel.org>