On Wed, Jan 18, 2017 at 5:40 PM, Sagi Grimberg [off-list ref] wrote:

quoted

Your report provided this stats with one-completion dominance for the
single-threaded case. Does it also hold if you run multiple fio
threads per core?

It's useless to run more threads on that core, it's already fully
utilized. That single threads is already posting a fair amount of
submissions, so I don't see how adding more fio jobs can help in any
way.

With a single thread, your completion processing/submission is
completely serialized. From my experience, it takes fio couple of
microsec to process completion and submit next request, and that'
(much) larger than your interrupt processing time.

Regards,
Andrey