Just to share my experience on this subject: I recently tested LAM-MPI
on a double-network cluster (Sueprmicro 2-Xeon boards with 2 e1000 NICs
and 2 Gigabit switches), but I did not get a bandwidth improvement from
the second network, more in detail:
1. Using channel bonding I did not get any improvement in bandwith even
with ttcp, so I didn't bother testing MPI.
2. Using differemt communication paths between different nodes I got a
slight improvement in ttcp bandwidth (node A communicating
simultaneously to nodes B and C using the 2 different networks gave an
overall bandwidth a little bit higher than just A-B comunication, but
far from double); unfortunately LAM-MPI in this case (with lamboot -l
and all setup according to Tim Mattox suggestions) didn't give any
performance improvement in a send/receive test, although I verified that
both networks were being used.
I cannot swear that I did everything right, but if it is the case, I
feel that the bottleneck that prevents the bandwidth increase is in the
hardware (or in the kernel), because a previous test with LAM on a
double 100Mbit/s network (whose results are in a mailing list message
cited by Mark) were positive.
Bye , Davide
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Davide Cesari ARPA-Servizio Idro Meteorologico __
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fax (39) 051/6497501 |||\
e-mail dcesari at smr.arpa.emr.it |||/
www http://www.arpa.emr.it/sim ---
Address: ARPA-SIM, Viale Silvani 6, 40122 Bologna, Italy
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