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Subject: Re: [OMPI users] Accessing OpenMPI processes over Internet using ssh
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-11-30 06:16:49

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.

Jeff Squyres
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