Re: [PATCH] make blk_mq_map_queues more friendly for cpu topology

From: Christoph Hellwig
Date: Wed Mar 27 2019 - 04:16:31 EST

On Tue, Mar 26, 2019 at 03:55:10PM +0800, luferry wrote:
> At 2019-03-26 15:39:54, "Christoph Hellwig" <hch@xxxxxx> wrote:
> >Why isn't this using the automatic PCI-level affinity assignment to
> >start with?
> When enable virtio-blk with multi queues but with only 2 msix-vector.
> vp_dev->per_vq_vectors will be false, vp_get_vq_affintity will return NULL directly
> so blk_mq_virtio_map_queues will fallback to blk_mq_map_queues.

What is the point of the multiqueue mode if you don't have enough
(virtual) MSI-X vectors?