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Subject: Re: [OMPI devel] Bug btl:tcp with grpcomm:hier
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-03-16 20:15:51

On Mar 16, 2011, at 5:37 PM, George Bosilca wrote:

> I just checked and IB does work correctly. But then I remembered that IB is different, the connection are peer based, so they don't happens during the modex exchange. The data is exchanged over RML messages, but outside the modex.

Not quite. The openib BTL does use the modex to send around connection information. The actual connections are made lazily -- just like the TCP BTL -- but the OOB CPC (i.e., the default connection mode in the openib BTL) uses RML to do the 2/3 way handshake. That's all.

But the point here is: the openib BTL does rely on the modex.

Jeff Squyres
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