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Subject: Re: [OMPI devel] SDP support for OPEN-MPI
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2008-01-18 18:18:55

On Jan 15, 2008, at 3:57 AM, Lenny Verkhovsky wrote:

>> Ah, you meant the listener socket -- not 2 sockets to each peer. Ok,
>> fair enough. Opening up one more listener socket in each process is
>> no big deal (IMO).
> I thought in a large cluster it can be a problem.

If you're adding one more listener socket in each process, that's no
big deal. That's an O(1) increase -- not an O(N) (or O(N^2)) increase.

>> Perhaps I don't understand exactly what you are proposing. I was
>> under the impression that you were going after a common case: mpirun
>> and the MPI jobs are running on back-end compute nodes where all of
>> them support SDP (although the other case of mpirun running on the
>> head node without SDP and all the MPI processes are running on back-
>> end nodes with SDP is also not-uncommon...). Are you thinking of
>> something else, or are you looking for more flexibility?
> I am just looking for more flexibility for the end user.

Can you cite some specific use-cases that you want to be able to
support? I think we're talking around in circles because we're
talking about different scenarios.

Jeff Squyres
Cisco Systems