Advanced Micro Devices Inc (AMD)

[Haddock]

I was quite frankly shocked by the processor comparison data in this presentation. Clearly there
are factors here, real or artificial, that don't allow all the machines to perform up to their potential.

Since the 21364 does so well, shouldn't we be looking at the feature that the 21364 is so good at, namely having multiple outstanding memory transactions going on at the same time. In this scenario the app is a real cache-buster and spends its entire time waiting on small items from memory. So the machines that shine are the 21364 and (to a lesser extent) the Opteron.

Just an idea. This would make the apps rather unusual HPC apps in my book. They are mostly simulations of large explosions as far as I can gather from the info I linked to in this subthread, but I don't know the details of the algorithms they name.

I mailed the author of the presentation and asked him FWIW.

Why were I2 tests reported as "about the same as
P4@2GHz" instead of an actual number?

The real figures can be estimated from the graph on the next page. The I2 is actually much slower than the P4!

They mention that for another of their apps, the "Sam Key" part of SPECfp2000 turns out to be a good predictor. By this they mean "fma3d", written by Sam Key: http://www.specbench.org/cpu2000/CFP2000/191.fma3d/docs/191.fma3d.html

You can see on
http://www.spec.org/cpu2000/results/res2003q3/cpu2000-20030616-02227.html
and
http://www.spec.org/cpu2000/results/res2003q1/cpu2000-20030113-01917.html
that the Alpha (at only 1150MHz) is indeed faster than the Itanium 1.5GHz 6M (1364 vs. 1063 peak).