[Beowulf] AMD 8 cores vs 12 cores CPUs and Infiniband

Gilad Shainer Shainer at Mellanox.com
Fri Apr 1 15:41:07 PDT 2011

> > I have been using single card on Magny-Cours with no issues at all.
> You can
> interesting.  what adjustments have you made to the MPI stack to
> this?
> we've had a variety of apps that fail intermittently on high-core
> nodes.
> I have to say I was surprised such a thing came up - not sure whether
> it's
> inherent to IB or a result of the openmpi stack.  our usual way to
> this is to gradually reduce the ranks-per-node for the job until it
> starts
> to work.  an interesting cosmology code works at 1 pppn but not 3 ppn
> on our recent 12c MC, mellanox QDR cluster.

I will be more than happy to give it a try - have access to the
Magny-Cours system at

> regards, mark hahn.
> _______________________________________________

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