[Beowulf] Re: Benchmark results

Michael Will mwill at penguincomputing.com
Tue Jan 6 12:53:13 EST 2004


Rene,

Do you see that fluctuation only on the opterons or also on the intel cpus
(I assume Xeon?)

If it was only on the opteron, then you will have node memory interleave
turned off in your bios, and sometimes the data you work with is close to
your CPU and sometimes far. (each CPU has a bank of RAM and accesses the
other CPUs bank through hypertransport, which is slower)

When running a memory and floatpoint intensive benchmark (neuronal network
training program like SNNS), we got two consistent results: They were
alternating, depending on which CPU the code ran, and they were 20% off of
each other for that setup.

Once we put in the same amount of memory in both banks, and turned on
'node memory interleave' in the bios, they were consistently between the
two, a bit closer to the faster value.

I will take a closer look at your CD later, too.

Michael Will
PS: Did I mention the opterons blew away the xeons by far?
-- 
Michael Will, Linux Sales Engineer
Tel:  415.358.2673  Toll Free:  888-PENGUIN
PENGUIN COMPUTING - The World's Most Reliable Linux System
www.penguincomputing.com


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