Hi Glen, what setup have you used for doing the benchmarks? I mean, what type of Ethernet switch, which network cards, which linux kernel. I am asking because it looks weird to me that the 4 CPU OpenMPI job is taking longer than the 2 CPU job, and that the 8 CPU job is faster again. Maybe the network settings can be optimized?
Regards, Carsten On Thu, 2 Feb 2006, Glen Kaukola wrote: > Hi everyone, > > I recently took Open MPI (1.0.2a4) for a spin and thought you all might > like to see how it's currently stacking up against MPICH (1.2.7p1). The > benchmark I used was the EPA's CMAQ (Community Multiscale Air Quality) > model. > > Now bear in mind my results aren't completely scientific. For one thing > I'd need to run a series of jobs and take the averages. Forgive me if > I'm too lazy to do that. I also didn't go through the trouble of > completely isolating my jobs while they were running. However, I did > monitor them pretty closely and I'm fairly certain no jobs from other > users crept in on the machines I was using. > > Anyway, without further ado, here are my results (in h:mm): > > Open MPI > 1 cpu job: 2:38 > 2 cpu job: 1:26 > 4 cpu job: 1:38 > 8 cpu job: 1:08 > 36 cpu job: 3:09 > > MPICH > 1 cpu job: 2:38 > 2 cpu job: 1:27 > 4 cpu job: 0:48 > 8 cpu job: 0:32 > > And while Open MPI does seem a bit slower, one real nice thing I can say > is that a 16+ cpu job runs without a hitch. I could never get away with > that while using MPICH, as the jobs would just crash. Whether MPICH is > at fault, or the CMAQ code is buggy, or gigabit ethernet just isn't good > enough, I really couldn't say. But Open MPI sure doesn't seem to have > that problem. > > It's also rather odd how the 4 cpu Open MPI job takes longer than the 2 > cpu Open MPI job. In fact that's slightly faster compared to the first > time I ran a 4 cpu Open MPI job (I couldn't believe it the first time so > I reran that one). > > And on a totally unrelated note, after swapping out MPICH for Open MPI, > I can't seem to background my scripts. When I do my shell (bash) tells > me the job has stopped. Somewhat annoying. > > Anyway, keep up the good work. I'll be paying close attention, and > hopefully see some speedups in the not too distant future. > > > Glen > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
