Why NVMe MSIx vectors affinity set across NUMA nodes?

[Keith Busch]

On Mon, Jan 22, 2018 at 11:42:45PM +0530, Ganapatrao Kulkarni wrote:
> 
> AFAIK, usually drivers sets default affinity and it is likely be node
> affinity for NUMA systems.
> Later, it is the user-space(like irqbalance etc) which decides the
> affinity not the driver.

Relying on userspace to provide an optimal setting is a bad idea,
especially for NVMe where we have submission queue cpu affinity that
doesn't work very efficiently if the completion affinity doesn't match.