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<TITLE>RE: Estimating Cluster Performance</TITLE>
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<P><FONT SIZE=2>> I plan on using the FFTW package from <A HREF="http://www.fftw.org" TARGET="_blank">http://www.fftw.org</A></FONT>
<BR><FONT SIZE=2>> <<A HREF="http://www.fftw.org" TARGET="_blank">http://www.fftw.org</A>> and they have compiled some benchmarks at</FONT>
<BR><FONT SIZE=2>> <A HREF="http://www.fftw.org/benchfft/results/alpha467.html" TARGET="_blank">http://www.fftw.org/benchfft/results/alpha467.html</A></FONT>
<BR><FONT SIZE=2>> <<A HREF="http://www.fftw.org/benchfft/results/alpha467.html" TARGET="_blank">http://www.fftw.org/benchfft/results/alpha467.html</A>> . That leads me</FONT>
<BR><FONT SIZE=2>> to believe that one box can basically sustain 200 MFLOPs.</FONT>
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<P><FONT SIZE=2>Gary,</FONT>
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<P><FONT SIZE=2>The benchmark results you've pointed to are for the previous generation EV56 instead of the EV67's that you'll be buying. The EV67 is often twice as fast at the same clock as the EV56. However, you're also talking about a situation where main memory bandwidth is critical. The DS10L sustains about 3x the memory bandwidth of the 4100.</FONT></P>
<P><FONT SIZE=2>If you want a single-node FFTW run on similar hardware, sign up for the Compaq "test drive" program.</FONT>
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<P><FONT SIZE=2>> Now, I am</FONT>
<BR><FONT SIZE=2>> making an assumption that distributing FFTs among nodes is very balanced</FONT>
<BR><FONT SIZE=2>> (scaleable? parallelizable? whats the term I'm looking for here?) and</FONT>
<BR><FONT SIZE=2>> therefore it will scale well</FONT>
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<P><FONT SIZE=2>That depends on the details. Are you talking about dividing the data into chunks, FFTing them separately, and not worrying about the longest frequencies? If so that's fairly embarrassingly parallel, and will scale well.</FONT></P>
<P><FONT SIZE=2>-- greg</FONT>
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