[PATCH] nvme-multipath: implement active-active round-robin path selector

[Keith Busch]

On Fri, Mar 30, 2018 at 09:04:46AM +0000, Eric H. Chang wrote:
> We internally call PCIe-retimer as HBA. It's not a real Host Bus Adapter that translates the interface from PCIe to SATA or SAS. Sorry for the confusion.

Please don't call a PCIe retimer an "HBA"! :)

While your experiment is setup to benefit from round-robin, my only
concern is it has odd performance in a real world scenario with
IO threads executing in different nodes. Christoph's proposal will
naturally utilize both paths optimally there, where round-robin will
saturate node interlinks.

Not that I'm against having the choice; your setup probably does represent
real use. But if we're going to have multiple choice, user documentation
on nvme path selectors will be useful here.