[Beowulf] ***UNCHECKED*** HPCG

[Prentice Bisbal]

Beowulfers,

Do any of you have any experience using HPCG as a benchmark. I'm trying 
to compare the performance of several different processors for an 
upcoming purchase. I've already run LINPACK, and now I'd like to run 
HPCG. It seems the only tuning parameter is the size of the local grid 
in the x,y,z dimensions.

While the guidelines say to increase the gridsize until the job consumes 
1/4 or more of RAM, my testing has shown that as the gridsize goes up, 
so does the performance,  and it keeps going up for me until I consume 
all the memory and the job gets killed by Slurm for exceeding memory 
requirements.

I've been doing a lot of Google searching for how to tune HPCG for 
maximum results, and there are some papers for tuning HPCG for large 
supercomputers. In these cases, they use x,y,z dimensions that are not 
necessarily equal, but I don't understand how they determined to use 
these unique values for x,y,z.

When I compare my HPL results to my HPCG results, I'm getting HPCG 
results that are 0.3 - 0.5% of HPL. On the HPCG Top500 list, most 
systems are getting 2-3% of HPL, so I'm off by an order of magnitude.

-- 
Prentice