[PATCH] nvme: set DMA_ATTR_WEAK_ORDERING attribute on dma buffers

Sat Jun 17 04:57:03 PDT 2017

On Fri, Jun 16, 2017 at 01:34:50PM -0700, Alan Adamson wrote:
> SPARC based platforms suffer significant read performance penalties for
> nvme reads when Relaxed Ordering is not enabled. This change sets the
> DMA_ATTR_WEAK_ORDERING (Relaxed Ordering) attribute for nvme block dma
> buffers.

Please explain what it does exactly, and why you think it's safe for NVMe,
as that belongs into the changelog.

Bonus points for explaining why DMA_ATTR_WEAK_ORDERING shouldn't
be the default behavior for the dma_map_ routines instead of sprinkling
it over just about every driver..