[ofa-general] Re: Re: [PATCH RFC] sharing userspace IB objects

[Michael S. Tsirkin]

> Looking at the Dror's slides on slide 6 "Scalable Reliable Connection" I
> see that wire protocol is extended to send DST SRQ as part of a header.
> Receiver side then puts completion to appropriate CQ according this
> field. Have you proposition address this? How? Who will put this
> additional data on a wire (HW or libibverbs may be app)?

This is SRC, which is a hardware extension, and is mostly an orthogonal issue.
My proposal only deals with SSQ for now.
For SRC we'll need to define a new "SRC domain" objects and API to share them
between apps. I expect that we'll be able to basically use the same API as for
sharing other objects.

It is true that for best scalability we probably need both SSQ and SRC,
but let's try to focus on sharing APIs for now.

> Also I don't see this in Dror's slide, but completion of local operation should
> be demultiplexed to appropriate CQ too. WQE may contain additional field, for
> instance, that will tell where to put a completion. Once again who will do the
> demux in you proposition (HW, libiverbs or app)? The right answer is most
> certainly HW in both cases so will Hermon support this?  Or may be you want to
> demultiplex everything inside libibvers? In this case I want to see design of
> this (preferably with performance analysis).

Since hardware can not do this demultiplexing, I think the right thing
is to do this inside MPI, encoding the necessary data in the WRID field.

-- 
MST