[dat-discussions] [openib-general] [RFC] DAT2.0immediatedataproposal

[Larsen, Roy K]

One thing to keep in mind is that the IBTA workgroup responsible for the
transport wanted to eliminate immediate data support entirely but it was
retained solely to enable VIA application migration (even though the
application base was quite small).  If that requirement could have been
eliminated, then it would have been gone in a heart beat.  Given a
RDMA-WRITE followed by a SEND provides the same application semantics
based on the use models, iWARP chose not to support immediate data. 

 

Mike, 

 

I was not part of the original IBTA discussions and I won't argue
whether this facility should or shouldn't have been include.
Nevertheless, it is part of the specification, there are HCA vendors
that implement it, and we have applications that make use of it.  I
would, however, disagree with your assertion that write followed by a
send is semantically equivalent to write immediate.  Ordering may be
semantically the same, but the service is not.  Receive work completions
are explicitly indicated as being associated with immediate data and
therefore an associated write completion.  A write followed by a send
does not provide the same indication semantic.

 

Roy

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openfabrics.org/pipermail/general/attachments/20060208/27180413/attachment.html>