[CIG-MC] Citcom runtime on Lonestar vs Ranger (Teragrid): Insights/experience?

Erin Burkett erburkett at ucdavis.edu
Sat Feb 20 19:07:19 PST 2010

Hi all,
For those of you who have experience running versions of Citcom on the
Teragrid (specifically Lonestar and Ranger), I am seeking some
insight/advice to help understand and minimize/eliminate (if possible) the
longer runtimes I'm currently encountering on Ranger (vs. Lonestar).

I'm attaching a table summarizing timing results of a small test I've run
using various combinations of the different compilers, compiler options,
mpicc versions.  This follows an earlier run on 480 processors resulting in
a 20% longer runtime on Ranger vs Lonestar that first caused me to be aware
of the difference.

I have gathered that because Lonestar has 4 cores/machine and Ranger has 16
cores/machine, the interconnect speed (Citcom uses interconnect heavily/is
communications intensive?) may be limiting the speed despite Ranger being
more powerful.

I would appreciate any shared experience, suggestions, or insights you may
have to help identify the best machine and specifications to use for running
Thank you!

Erin R. Burkett
University of California, Davis
2205 Earth and Physical Sciences
Davis, CA 95616

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