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Subject: Re: [OMPI devel] Multi-rail on openib
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2009-06-05 09:52:39


See this FAQ entry for a description:

     http://www.open-mpi.org/faq/?category=openfabrics#ofa-port-wireup

Right now, there's no way to force a particular connection pattern on
the openib btl at run-time. The startup sequence has gotten
sufficiently complicated / muddied over the years that it would be
quite difficult to do so. Pasha is in the middle of revamping parts
of the openib startup (see http://bitbucket.org/pasha/ompi-ofacm/); it
*may* be desirable to fully clean up the full openib btl startup
sequence when he's all finished.

On Jun 5, 2009, at 9:48 AM, Mouhamed Gueye wrote:

> Hi all,
>
> I am working on multi-rail IB and I was wondering how connections are
> established between ports. I have two hosts, each with 2 ports on a
> same IB card, connected to the same switch.
>
> My question is : how ports are connected between them ? Is there a
> queue
> pair between all ports or only between ports of the same number (for
> example, Host A => port 1 <===> port 1 <= Host B and Host A => port 2
> <===> port 2 <= Host B or maybe Host A => port 1 <===> port 2 <=
> Host B
> and Host A => port 2 <===> port 1 <= Host B) ? Is it possible to force
> the connection scheme on the openib btl ?
>
> Thanks
>
> Mouhamed
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>

-- 
Jeff Squyres
Cisco Systems