[ofiwg] descriptive terminology for libfabric
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.
> -----Original Message-----
> Sent: Thursday, August 06, 2015 2:49 PM
> To: Paul Grun
> 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?
> 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
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