Re: [PATCH 1/3] nvme/pci: Start request after doorbell ring

Keith Busch
2017-12-21T21:02:50Z

On Thu, Dec 21, 2017 at 01:53:44PM -0700, Jens Axboe wrote:
> Turns out that wasn't what patch 2 was. And the code is right there
> above as well, and under the q_lock, so I guess that race doesn't
> exist.
>
> But that does bring up the fact if we should always be doing the
> nvme_process_cq(nvmeq) after IO submission. For direct/hipri IO,
> maybe it's better to make the submission path faster and skip it?

Yes, I am okay to remove the opprotunistic nvme_process_cq in the
submission path. Even under deeply queued IO, I've not seen this provide
any measurable benefit.