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I wonder if someone has run into this before. I compiled one of our CFD solvers on OS X using MPI, and have been testing it on a variety of G4 and G5 systems. When I run across multiple machines using only one processor per machine, the performance is great. When I use dual processors, however, the problem takes forever to setup (initial communication overhead of the flow solver I assume) and then cranks OK once the iterations start. I was expecting some penalty when running dual processors as they compete for bandwidth, but it seems way too slow. In fact, I could manually run about a dozen single CPU cases in the time it takes for one dual-processor case to get going. Any ideas or suggestions?? Thanks, Craig -- Dr. Craig Hunter NASA Langley Research Center AAAC/Configuration Aerodynamics Branch email@hidden (new!!) (757) 864-3020 (Dual G4 - OS X) _______________________________________________ Do not post admin requests to the list. They will be ignored. Scitech mailing list (email@hidden) Help/Unsubscribe/Update your Subscription: This email sent to email@hidden
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