Motherboard / Benchmark Questions...

[Dean Waldow]

(I hope this only arrives on the list once since there were some mailing problems.)

Hi,  I am trying to settle on hardware for building our cluster and have
some motherboard / benchmark related questions.  (Sorry if I missed any
discussions/FAQ's...)

I have benchmarked my monte carlo code on what machines I could access. 
The monte carlo code is in the 'embarrassingly parallel' class with some
potential for parallelization with another version which includes
significant numbers of fourier transforms. (given our small budget - we
looked at celeron 400Mhz, PIII katmai 512K cache dual 600MHz, and a PIII
Cu-mine 550MHz 256K cache and not alpha's)  The benchmark was simply how
long it took my actual simulation to complete.  The results seem a
little surprising since I thought celeron's might be more competitive...
We compared the three basic systems mentioned above normalizing within a
processor class to clock speed.  We also tried to estimate a benchmark
time for athalons which is most likely a poor estimate (assuming equal
performance to a PIII and scaling to clock speed). We looked at our
budget, estimates in price from pricewatch.com, and benchmark numbers.
We then calculated the number simulations we could run on the
hypothetical cluster in a day: celeron's systems were the slowest, with
PIII and PIII duals basically equivalent at about a 25% increase in
throughput, and lastly (using an estimate for athalons) hypothetically
came out the highest with an additional ~15% increase in throughput over
the PIII's.  I am not confident in that estimate but it is interesting
and would likely be heavily code specific.

On one level, the differences in throughput are not terribly significant
compared to the increase  I will be able to get on a cluster vs. the
current machines I have.  Thus, I am left with a few questions that if
anyone might have comments on that would be great.  If these questions
may not have as much general interest, I could summarize off-list
comments later.   

1)  Since my tests indicate little difference in throughput for single
cpu vs. dual cpu nodes, are there other advantages one way or the other
in using dual vs. a single cpu nodes? 

2) In the case of the PIII processor, the question seems to be one of a
mainboard choice which in turn is mostly about chipsets - right?  From
what I have read...  The two chipsets that seem prevalent are the 440BX
and the VIA Apollo 133A.  The newer intel chipsets (i8xx) make me a
little cautious from what I have read though that may be mostly due to
the i820.  The 440BX boards sound well tested and stable performers but
on the "older side" without much difference in price.  The VIA Apollo
133A seems like it would have advantages if code is benefited by the
133FSB and PC133 memory. Does this summary make sense? And are there
folks successfully using the newer chipsets? :)

3) Since I have not been able to benchmark my code on an athalon, does
anyone have experience in comparing performance on athalons versus
PIII's for a real world example?  Or, are the performance differences
really so code dependent that it is difficult to "generalize."  8-)  The
potential for increased throughput is tempting but without better
estimates the stability/certainty of the PIII maybe more important in
the long run.

Thanks for any input and I hope these questions are not too simple...

Dean W.
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Dean Waldow, Associate Professor      (253) 535-7533 
Department of Chemistry               (253) 536-5055 (FAX)
Pacific Lutheran University           waldowda at plu.edu
Tacoma, WA  98447   USA               http://www.chem.plu.edu/waldow.html
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