[mesa-users] Using MESA on a 16 core machine

Bill Paxton paxton at kitp.ucsb.edu
Sat Jul 9 17:45:36 EDT 2011

Hi Nathan,

MESA will use OpenMP by default, and OpenMP will use the number of threads specified by the environment variable OMP_NUM_THREADS.
So you can do setenv or export to control how many threads are used.

My impression has been that the ifort implementation of OpenMP was significantly better than the gfortran one, but I haven't done a careful comparison.

But if you are interested in improved performance, you should see if there is any way to get ifort.   You might at least try a "free sample period" to compare.

Getting mesa/star to make good use of more than 3 or 4 cores is a challenge that I'm working on, but we're not there yet.



On Jul 9, 2011, at 2:22 PM, Nathan Thompson wrote:

> Hello, 
> My name is Nathan Thompson and I am a graduate student at Wichita State University. I have been using MESA on my personal computer for about a year to do computations. It is an Intel i7 860 machine (four cores) and does well with the computations.
> Recently, I was given an account on a university computer in order to use that to do computations, a 16 core machine of which I am not 100% sure of the processor type, but I was assured that each of its cores were faster than my i7. However, when I ran the same model in MESA on both boxes, my PC did the computations twice as quickly as the university machine (and I had full use of all 16 cores). Both versions of MESA were compiled using gfortran.
> I know the MESA is "thread safe" as stated by the website, but performance is noted to not increase with additional processors. Is there an option that I need to set in MESA to activate the use of OpenMP for multiple threads, or is this enabled "out of the box?" Also, is there a way to limit the number of cores MESA has access to, so that I can test to see if one of these cores is indeed faster than my i7?
> Thanks,
> Nathan Thompson
> Wichita State University
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