Athlon vs. PIII

Troy Baer troy at
Tue Feb 20 07:59:03 PST 2001

On Tue, 20 Feb 2001, Ole W. Saastad wrote:
> I have run a few tests to check the performance of
> Athlon vs. PIII. 
> The Atlas (tuned BLAS libs) tests suggest very high 
> performance for Athlon, however in real tests like
> Gaussian 98 there is little difference. 
> Summary of performance Athlon vs. PIII 
> - with Gaussian98 runs.
> pgf77 (cache size 512k)
> Athlon:  22 minutes 26.8 seconds.
> PIII:    17 minutes 57.3 seconds.
> pgf77 (cache size 64k)
> Athlon:  23 minutes  5.8 seconds.
> PIII:    17 minutes 56.3 seconds.
> Compiled with pgf77.
> pgf77  -O2 -tp p6 -Munroll -Mvect=cachesize:524288 -c redund.f
> Cache size 512k.
> Included Blas code compiled. 

Compiling with "-tp p6" is arguably the wrong thing to do on an Athlon, if
that's what you did.  Try either compiling with "-tp athlon" on the Athlon
or leaving out the -tp flag altogether (the compiler is supposed to figure
out what processor it's on if it's not specified).

Also, enabling prefetching (-Mvect=prefetch) may improve performance by
10-15% on both the Pentium III and the Athlon.

Troy Baer                       email:  troy at
Science & Technology Support    phone:  614-292-9701
Ohio Supercomputer Center       web:

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