On Mon, May 11, 2009 at 6:22 PM, Gus Correa <g...@ldeo.columbia.edu> wrote: > Oops, I misunderstood what you said. > I see now. You are bonding channels on the your nodes' dual GigE > ports to double your bandwidth, particularly for MPI, right?
Yes. Each node has dual gigabit eth cards. > I am curious about your results with channel bonding. > OpenMPI claims to work across two or more networks without the need > for channel bonding. > What MPI do you use? We use OpenMPI. I've never really found a good way to measure my performance. I've tested bandwidth and it definately improves. So also file transfer times. But I have not tried any computation relevant benchmarks. It also seems very much a function of what channel bonding mode is used. The relevant modes seem to be able to split traffic only when talking to two different hosts at the same time. So a strict peer to peer communication is not affected at all. At least so far as I understood those intricacies. To set or not to set LAG groups on the switch was another factor. A lot of that stuff seemed to be manufacturer specific on the switch. > In any case, the single 24-48 port GigE switches (if of good brand) > should have a single flat latency time between any pair of ports, right? I think bonding improves bandwidth. But does not touch latency. My brand's Dell. PowerConnect. Not sure if that fits "good brand" definitions. -- Rahul _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
