[PATCH V3] nvme-pci: add sgl support

[Keith Busch]

On Tue, Aug 01, 2017 at 08:29:00AM +0000, Chaitanya Kulkarni wrote:
> [CK] Yes, I've observed approximately %5 better
> performance for IO sizes larger than 32k (for sgl_threshold = 32k).

Is that a physically contiguous 32k, or does each 4k require a different
SG element? Could you try to force both conditions and see how each
scenario compares with PRP?