[PATCH V2 0/2] nvme: replace linked list with xarray for ns tracking

[Keith Busch]

On Wed, Jul 01, 2020 at 07:36:09AM +0200, Christoph Hellwig wrote:
> On Tue, Jun 30, 2020 at 07:25:15PM -0700, Chaitanya Kulkarni wrote:
> > Hi,
> > 
> > This is a small patch-series which replaces ctrl->namespaces with
> > xarray for host-core and target-core. We can see following
> > performance improvement when running fio with 32 parallel jobs where
> > first 16 namespaces and last 16 namespaces are used for I/O. See [1] for
> > detailed performance numbers. 
> 
> Why would that make any difference given that we don't look up namespaces
> in the I/O path?

Not in host side. Target does a lookup on each IO through:

  nvmet_req_init()
    nvmet_parse_io_cmrd()
      nvmet_find_namespaces()

And this detail should be mentioned in the test setup for the cover
letter, or in patch 2.