Re: [dpdk-dev] eventdev DSW question

["Mattias Rönnblom" <mattias.ronnblom@ericsson.com>]

On 2019-12-06 17:32, Venky Venkatesh wrote:
> Thanks Mattias for the clarifications.
> 
> 1 more question: This time it is about the inflight accounting for DSW.
> Here is my understanding: it seems to consider only the events which
> are *inside
> the scheduler* as in flight.

Yes, like all event devices, I believe.

> I am trying to distinguish it from those which
> have been currently given to cores by the scheduler. The latter are not
> considered in flight since we dsw_port_return_credits as soon as
> dsw_event_dequeue_burst.

A new dequeue means an implicit release of all unreleased events 
dequeued in the previous call. It's standard Eventdev semantics.

> So if these events which are in core currently do
> a FORWARD, there is a chance that those can fail. Ideally those FORWARDs
> should not fail -- which can happen with the current design as some NEWs
> can hog those credits freed up by the ones which have been dequeued by
> cores.

What you do to avoid this situation is set the new_event_threshold 
low-enough, so NEW events don't block FORWARDed ones.

> Is this design of DSW intentional or an omission? If it is an
> omission I can work on a possible fix and run it by you.
> 

This is not really a DSW design, but rather how Eventdev works.