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Subject: Re: [OMPI users] Accessing OpenMPI processes over Internet using ssh
From: Jaison Paul (jmulerik_at_[hidden])
Date: 2011-11-30 15:02:58


Jeff Squyres <jsquyres <at> cisco.com> writes:

>
> On Nov 30, 2011, at 6:03 AM, Jaison Paul wrote:
>
> > Yes, we have set up .ssh file on remote EC2 hosts. Is there anything else
that we should be taking care of when
> dealing with EC2?
>
> I have heard that Open MPI's TCP latency on EC2 is horrid. I actually talked
with some Amazon / EC2 folks about
> it at SC'11 a few weeks ago; we set a date to dive into it a bit deeper in
December.
>
> No promises on when/if the TCP latency will improve, but it's definitely
something that we're looking at.
> My first *guess* is that it might have something to do with specifying
btl_tcp_if_include /
> oob_tcp_if_include improperly (or not at all) -- but that's a SWAG.
>

Yes Jeff,

We are not setting up --mca btl_tcp_if_include / --mca oob_tcp_if_include at all
at the moment. What will be the best setup to access EC2 hosts over internet for
--mca btl_tcp_if_include / --mca oob_tcp_if_include? I dont understand --mca
very well.

Thanks, Jaison