SUPERCOMPUTER USERS EXPERIMENT WITH CM-5, BEGIN 
PRODUCTION COMPUTING
by Bill Buzbee, NCAR Scientific Computing Division (SCD)
and Gary Jensen, NCAR SCD 

 Connection Machine-5 (CM-5) from Thinking Machines Corporation 
is currently testing three major supercomputer models through 
NCARÕs Scientific Computing Division. The machine, which arrived 
at NCAR in May of last year, is an example of the massively parallel 
processor  supercomputers many modelers are hoping to rely on for 
tackling Ògrand challengeÓ problems requiring unprecedented speed 
and memory.  The largest CM-5 in the world, at Los Alamos National 
Laboratory, has 1,024 processing units with a peak speed of 128 
gigaflops.  NCARÕs comparatively modest 32-processor version has 
been used to date as a tool for designing, porting, and testing parallel 
codes. Usage has been steadily increasing, and SCD has now dedicated 
12 hours each weeknight and full time on weekends to production 
computing.

Three major production applications are either running now or will 
soon be.

--3-D Geophysical Turbulence ModelÑMuch of the CM-5 time over the 
past few months has been spent on a three-dimensional turbulence 
code simulating vertical variation in density. Yoshi Kimura of NCARÕs 
Mesoscale and Microscale Meteorology Division heads this effort.

--The NCAR Semtner-Chervin Global Ocean SimulatorÑThe 
Semtner-Chervin global ocean model has been adapted at the Los 
Alamos National Laboratory for use on its CM-5.  That Los Alamos 
data-parallel implementation is in hand and ready for production use.

--The NCAR Community Climate Model, Version 2 (CCM2)ÑHaving 
the CM-5 has greatly accelerated conversion of the CCM2 to a data-
parallel formulation, and the task is nearly complete. SCD is ready to 
begin model validation, which will require several long checkout 
simulations.

Other climate and computational chemistry codes are in various stages 
of development on the CM-5. In addition, students from the 
University of Colorado and Colorado State University are 
experimenting with parallel codes on the machine.

The bulk of the funding for the CM-5 was provided by the Defense 
Advanced Research Projects Agency through the National Consortium 
for High-Performance Computing.