[Beowulf] Gigabit Eithernet Ring

[steve_heaton at ozemail.com.au]

G'day all

I humbly kneel before the great collective and seek their tolerance of someone new to the Dark Art of Beowulf clustering ;)

Despite having spent 14 years in a past life working on "commercial" IT&T, I have now found the true use of such power is in the support of science. I'm slogging towards my Masters in Astronomy and Large Scale Structure dynamics is a passion. To this end I've built a small cluster to do some Nbody sims (and learn a bit about Beowulf clustering).

The short description is 4x dual P3's with gigabit Ethernet to an unmanaged switch (anyone with more than 4 nodes is just showing off ;)

The Nbody code uses MPI with a "pipe" (ring) IPC structure.
http://carol.wins.uva.nl/~spz/act/modesta/Software/src/nbody_sh1p.html

Question: Given that the MPI is performed using a ring
 would there be any advantage in using a "ring" (switchless) network topology over gigabit Ethernet?

I understand that Linux would then be responsible for the routing (as opposed to the dedicated hardware in the switch). But in return, I should get deterministic performance as opposed to probabilistic. Obviously the performance bottom line is what counts regardless!

Thoughts, comments, criticisms gratefully accepted. If the idea of a ring is a dud I can save myself the bucks! :)


Cheers
Steve

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