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From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2006-12-08 06:43:49

On Dec 8, 2006, at 5:41 AM, krishna chaitanya wrote:

> I learnt from a reliable source that MPI uses the
> services provided by TCP/IP or infiniband. Suppose that there is a
> bottle-neck in the

Keep in mind that MPI is a specification -- a document. There are
many software implementations of that specification, such as Open
MPI. Open MPI can use a variety of network transports to effect the
MPI semantics (e.g., the back end to MPI_SEND and MPI_RECV): TCP and
IB are two, but Open MPI supports several others (Myrinet, shared
memory, portals, ...). Additionally, there are other MPI
implementations that support other networks that Open MPI does not
currently support.

> TCP/IP layer itself, how will optimization of MPI calls really help?

I'm not quite sure what you're asking here. Open MPI generally
chooses the "best" network to transport most of its MPI traffic (both
point-to-point and collectives). See this FAQ entry:

Did that answer your question?

Jeff Squyres
Server Virtualization Business Unit
Cisco Systems