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MathGroup Archive 2000

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Re: Help! Mathematica on my 500MHz outperforms my GHz machine!

  • To: mathgroup at smc.vnet.net
  • Subject: [mg23120] Re: Help! Mathematica on my 500MHz outperforms my GHz machine!
  • From: "Martin Richter" <martin.richter at worldnet.att.net>
  • Date: Wed, 19 Apr 2000 02:30:50 -0400 (EDT)
  • Organization: AT&T Worldnet
  • References: <8d3s48$omg@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Just curios, that memory type did you use at your Pentium, also 100MHz bus
or 133MHz. Normally you get a boost upgrading the speed even on the purely
cpu-runtime test, so could it be Matematica way to handle the memory ? Have
you tried to running simulation test in a C/C++ environment ?

Martin

<terryis at my-deja.com> wrote in message news:8d3s48$omg at smc.vnet.net...
> Fellow Mathematica Users,
>
> After spending some time investigating the lackluster
> performance of my gigahertz Athlon machine I have finally
> discovered why it only performs at about the same level
> as my 500MHz Pentium III. In short my Athlon is bottle-
> necking on the relatively slow 100MHz bus between cache
> and main memory (as some of you had suspected).
>
> To start with I ran the various benchmarks suggested
> to me. From http://fampm201.tu-graz.ac.at/karl/mma.html I
> ran the MMA-Test.nb (for Mathematica 3.0) and got the
> following results:
>
>    Version   = Microsoft Windows 3.0 (April 25, 1997)
>    Times     =
> {0.531,0.591,0.18,0.371,1.91,0.661,0.181,0.28,0.551,0.641,0.47,0.862,0.5
> 81,0.49,0.461}
>    Total Kernel Time = 8.763,  Total Time = 9.
>    Benchmark = 11.2
>
> The benchmarks at www.scientificweb.com/sciencee/mathstef2.html could
> not be found and the ones at
> www.geocities.com/SiliconValley/Lab/2255/bytemark.html worked on one of
> my computers but gave a 'numeric sort' error condition on the gigahertz
> machine.
>
> The link 205.181.113.18/zdbop/zdbop2.html could not be contacted despite
> multiple attempts on different occasions.
>
>
> Next I split up my simulation and timed each piece individually
> on each machine. For each piece my Athlon kicked ass even though
> it performed poorly on the whole simulation. Finally I
> was able to localize the difference in performance to a
> single piece of code that saved intermediate results to
> memory. With the code to save intermediate results in,
> my Athlon took on average 27 minutes to run 25000
> iterations of my simulation compared to 24 minutes on the
> Pentium. Without the code to save intermediate results the
> Athlon was averaging 1 minute compared to 3 minutes on my
> Pentium! My conclusion was that without saving intermediate
> results, the sum total of all the parts of my simulation
> was able to fit completely in cache and so could run at the
> full 200MHz bus speed between cache and CPU. Interestingly
> enough the performance of the Pentium also improved
> dramatically (from 24 minutes down to an average of 3
> minutes!) which to me indicated that the cache hit ratio on
> the Pentium was not that high either.
>
> As it turns out, my simulations can be re-written to take
> full advantage of this machine. Even if I have to go back
> and re-run segments of my simulation to re-capture those
> intermediate results that are worth capturing, it's still
> worth it for me.
>
> Bottom line: if you are certain that what you are doing
> can fit into cache then this could very well be one of
> the faster machines for you to run Mathematica on.
> Otherwise I'd stick with a Pentium based machine.
>
> Finally check out
> www.zdnet.com/pcmag/stories/firstlooks/0,6763,2426421,00.html
> for a good article that sums up this machines deficiencies.
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
>



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