AMBER: Strange difference in speed between Altix (Itanium2) and Tezro (MIPS) SGI for small GB/SA run

From: <David.Maxwell.di.mdacc.tmc.edu>
Date: Wed, 3 Aug 2005 12:39:43 -0500

Hi Amber Users,

I noticed something strange when running a small protein GB/SA job on both
an 4-processor Altix (1.4 Ghz Itanium2) and a 4-processor Tezro (700 Mhz
MIPS) based SGI. Normally, I get a 2-2.5 speed difference in favor of the
Altix with running jobs with AMBER 8, submitting with mpirun -np4. This
makes sense based on the benchmarks I have seen. However, if I run
another set of jobs of the Altix at the same, the Altix seems to take
between 3-4 times as long to get done. This is not at all what I would
expect. I don't seem any memory, disk, or NFS issues. I am running many
other jobs at the same time, so it is difficult to get an exact figure,
but obviously something strange is happening. Any ideas on what could be
causing this?

-Dave
_____________________________________________
David Maxwell, Ph.D.
Senior Research Scientist
Dept. of Experimental Diagnostic Imaging
University of Texas M.D. Anderson Cancer Center
8012 El Rio St.
Houston, TX 77054
Phone: (713)-563-9963 Fax: (713)-563-0084
david.maxwell.di.mdacc.tmc.edu
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Received on Wed Aug 03 2005 - 18:53:00 PDT
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