[mpich-discuss] MPICH on multiple NICs, and how to choose the best computing node

[Gus Correa]

Hello MPICH experts

1) I wonder if MPICH2 (and/or MPICH-1) works with multiple 
(Gigabit)Ethernet NICs
installed on each computer node on a Linux/Beowulf cluster.

The naive idea here would be to increase network bandwidth and reduce 
contention by using multiple NICs.
Network contention may become an issue in the typical "eight core 
computer node"
that is popular now on the market (two-slot quad-core nodes).

I will need to buy a replacement for our small old cluster soon,
and I don't know what would be the most cost effective choice to run our 
MPICH-based code:
"two-slot quad-core nodes",  "two-slot dual-core nodes",
or other (single core processors seem to be an extinct species).

Of course, the price of one two-slot quad-core node is significantly 
less than the price
of a couple of two-slot dual-core nodes.
However, it looks like to me that MPICH may not be as efficient with 
eight cores sharing a single NIC,
as it would be in a two-slot dual-core node (four cores sharing a NIC).
Where the optimal price/performance point resides I don't know.

2) If MPICH does work with multiple NICs,
are there guidelines, documentation, or a recipe on how to set up a 
scheme like this?

3) Any other suggestions to avoid/reduce MPICH network contention in
multicore/multiprocessor computer nodes?
(Using OpenMP within the nodes is not so convenient, as it requires 
intensive re-coding,
and is not particularly simple or efficient in large programs. 
Buying Infiniband, Myrinet, etc, is not possible with our shoestring budget,
and I got to stick to and be happy with Gigabit Ethernet.)

If this question was discussed before, as it is likely to be the case,
please just point to me the right thread in the mailing list.

Many thanks,
Gus Correa

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Gustavo J. Ponce Correa, PhD - Email: gus at ldeo.columbia.edu
Lamont-Doherty Earth Observatory - Columbia University
P.O. Box 1000 [61 Route 9W] - Palisades, NY, 10964-8000 - USA
Oceanography Bldg., Rm. 103-D, ph. (845) 365-8911, fax (845) 365-8736
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