Re: [dpdk-dev] [RFC] [PATCH v2] libeventdev: event driven programming model framework for DPDK

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

On Wed, Oct 26, 2016 at 01:54:14PM +0100, Bruce Richardson wrote:
> On Wed, Oct 26, 2016 at 05:54:17PM +0530, Jerin Jacob wrote:
> > On Wed, Oct 26, 2016 at 12:11:03PM +0000, Van Haaren, Harry wrote:
> > > > -----Original Message-----
> > > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jerin Jacob
> Thanks. One other suggestion is that it might be useful to provide
> support for having typed queues explicitly in the API. Right now, when
> you create an queue, the queue_conf structure takes as parameters how
> many atomic flows that are needed for the queue, or how many reorder
> slots need to be reserved for it. This implicitly hints at the type of
> traffic which will be sent to the queue, but I'm wondering if it's
> better to make it explicit. There are certain optimisations that can be
> looked at if we know that a queue only handles packets of a particular
> type. [Not having to handle reordering when pulling events from a core
> can be a big win for software!].

If it helps in SW implementation, then I think we can add this in queue
configuration. 

> 
> How about adding: "allowed_event_types" as a field to
> rte_event_queue_conf, with possible values:
> * atomic
> * ordered
> * parallel
> * mixed - allowing all 3 types. I think allowing 2 of three types might
>     make things too complicated.
> 
> An open question would then be how to behave when the queue type and
> requested event type conflict. We can either throw an error, or just
> ignore the event type and always treat enqueued events as being of the
> queue type. I prefer the latter, because it's faster not having to
> error-check, and it pushes the responsibility on the app to know what
> it's doing.

How about making default as "mixed" and let application configures what
is not required?. That way application responsibility is clear.
something similar to ETH_TXQ_FLAGS_NOMULTSEGS, ETH_TXQ_FLAGS_NOREFCOUNT
with default.

/Jerin


> 
> /Bruce