> Most of the math used in POV is floating point. An Itanium 2 clains to
> run at 1.2 cycles per floating point operation. Various models of
> Pentium 4 claim to run at between 6.0 and 6.9 cycles per flop. Various
> models of Pentium 3 Xeon claim to run at between 3.3 and 4.7 cycles per
> flop. An Athlon XP claims to run at 4.3 cycles per flop.
> 
> So, theoretically,
> 1GHz Itanium 2   should perform a GigaFLOP in 1.3 seconds
> 3GHz Pentium 4   should perform a GigaFLOP in 2.0 to 2.3 seconds
> 2.8GHz Xeon      should perform a GigaFLOP in 1.2 to 1.7 seconds
> 2.5GHz Athlon XP should perform a GigaFLOP in 1.7 seconds
> 

Hey! That's interesting!
Where did you find those info?

>> There are many other entries which are difficult to believe as well.
>>For example a 1.8GHz Opteron being faster than a 2.5GHz Athlon XP.
> 1.8GHz Opteron @ 3.6 cycles per flop = GigaFLOP in 2.0 seconds
> 
> All other things being equal, one might expect the Athlon to be a little
> faster than the Operon (assuming we can trust the claimed cycles per
> flop figures). However, other things are never quite equal. For example
> the fact that the Opteron is listed as running Linux and the Athlon as
> running Windows XP will have made some difference. Things like cache
> sizes and memory speeds may also have an effect.
> 

You may also say that POV floating point operations are all on double 
precision: 64 bits.
Even if the Athlon-XP's FPU is able to use 64 bits double precision 
floats, it's internal structure is only 32 bits, so it need more time in 
the Athlon-XP to feed the FPU with it's needed 64 bits data than the 
Opteron, which has a 64 bits internal structure.

Regards,

-- 
Laurent ARTAUD (lau### [at] freefr)

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