Like to hear about opteron experiences

Bill Broadley bill at math.ucdavis.edu
Wed May 21 18:52:50 EDT 2003


I wrote a double precision based memory benchmark much like to John
McCalpin's stream, except I use a variety of array sizes and pthreads
to manage multiple parallel threads.

I found a dramatic difference in performance when running 2 or 4 threads.

For instance a dual p4 @ 2.4 Ghz (80% the clock of todays fastest p4):
http://www.math.ucdavis.edu/~bill/dual-p4-2.4-icc.png

Note that 2 threads has slower throughput then 1 to main memory.

Vs a dual opteron-240 (77% as fast as todays fastest opteron):
http://www.math.ucdavis.edu/~bill/dual-240-4xpc2700-icc.png

2 threads approximately 1.66 the throughput of 1 to main memory.

As an additional datapoint I made a run on a quad-842:
http://www.math.ucdavis.edu/~bill/4x842-icc.png

4 threads approximately 1.66 the throughput of 2 to main memory.

Not directly related to generalized double FP performance, but I
thought it might be an interesting data point.

These were all test accounts, I actually have 2 opteron cpu's in hand,
but alas I'm awaiting delivery of an opteron motherboard.

-- 
Bill Broadley
Mathematics
UC Davis
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