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Code Faster on Ubuntu Guest than on OSX Snow Leopard Host

Posted: 15. Jan 2010, 15:36
by egpaterson
I am running the open-source CFD code, OpenFOAM. I have compiled OpenFOAM natively on OSX using gcc 4.2.1, and on Ubuntu 9.10 guest OS using gcc 4.4.1. I have put the same appliance on both my laptop (MacBookPro 2.53 GHz Intel Core 2 Duo) and my desktop (2 x 3 GHz Quad-Core Intel Xeon) machines. Compiler optimization for OpenFOAM is set to -O3 on both systems. Running the same calculation on the Host (OSX) and the Guest (Ubuntu) gives the following timings:

MacBook Pro: OSX Host = 59 seconds; Ubuntu Guest = 43 seconds

Mac Pro: OSX Host = 60 seconds; Ubuntu Guest = 47 seconds.

Conclusions:

1. Even with the cost of virtualization, running on Ubuntu Linux is 20-25% faster than running on OSX. Is it the compiler version, or something in OSX?

2. MacBook Pro (2009) is faster than Mac Pro (2006), even though the clock-speeds are slower.