opteron VS Itanium 2 (Benchmark cheating)

[James Cownie]

> From way back with early linpack, this has left many benchmarks
> susceptible to vendor manipulation -- there are cases on record of
> vendors (DEC, IIRC, but likely others) actually altering CPU/memory
> architecture to optimize linpack performance because linpack was
> what sold their systems.

This certainly applied to some compilers which "optimized" sdot and
ddot by recognizing the source (down to the precise comments) and
plugged in a hand coded assembler routine.

Changing a comment (for instance mis-spelling Jack's name :-) or
replacing a loop variable called "i" with one called "k" could halve
the linpack result.

When $$$ are involved people are prepared to sail close to the wind...

-- Jim

James Cownie	<jcownie at etnus.com>
Etnus, LLC.     +44 117 9071438
http://www.etnus.com
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