[ofiwg] descriptive terminology for libfabric

asodder ieee asodder-ieee at sodder.us
Thu Aug 6 15:07:56 PDT 2015

I consider libfabric to be middleware that supports high
performance communications between connected processors.  I do not consider
it to be an IPC since to me that has typically been implemented over
sockets and used for application to application communication within a
processor or between processors for control data, i.e. not bulk data but
that could just be my narrow view of the world.


On Thursday, August 6, 2015, Paul Grun <grun at cray.com> wrote:

> This is a good question Doug.  Others should add, but I would say in your
> terms that libfabric exposes the details of RDMA, but at a higher level of
> abstraction than verbs.
> In other words, libfabric contains basically the same set of defined
> operations -channel operations (e.g. messaging/send receive), memory
> operations (RMA, nee RDMA), and Atomics.  But it exposes those to the
> consumer at a higher level of abstraction than does IB.
> User mode things like MPI are expected to be consumers of libfabric.  I'm
> not sure if ZeroMQ runs in user or kernel space.
> -Paul
> -----Original Message-----
> From: Oucharek, Doug S [mailto:doug.s.oucharek at intel.com <javascript:;>]
> Sent: Thursday, August 06, 2015 2:49 PM
> To: Paul Grun
> Cc: ofiwg at lists.openfabrics.org <javascript:;>
> Subject: Re: [ofiwg] descriptive terminology for libfabric
> I admit I have not spent much time looking at libfabric.  To me, for it to
> be IPC-focused, it needs to focus on message passing and hide all the
> details of transport such as RDMA mechanics.  Examples are MPI or ZeroMQ.
>  Is libfabrics like this or is it more like IB verbs where the programmer
> is subjected to the ugly details of RDMA?
> Doug
> On Aug 6, 2015, at 2:39 PM, Paul Grun <grun at cray.com <javascript:;>
> <mailto:grun at cray.com <javascript:;>>> wrote:
> Does anybody object to the shorthand description of libfabric as “an API
> designed to support user mode IPC operations”?   I am particularly
> interested if I am misusing the expression “IPC” here, which it seems to me
> describes perfectly what is happened in e.g. MPI (but then again, I’m not a
> computer scientist, so I may be misusing it).
> No need to be overly pedantic, but there is a need for accuracy in
> language.
> Thanks,
> -Paul
> Cray Inc.
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