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-   -   Hz vs. FLOP/s? (https://www.mersenneforum.org/showthread.php?t=2108)

ixfd64 2004-02-17 20:00

Hz vs. FLOP/s?
 
It seems that Hz are not always the same as FLOP/S...

For example, I've heard that some AMD 2.x GHz processors are faster than the P4 3.x GHz processors...

Is there a FLOP/s specification for processors? Just wondering. If so, where can I find reliable data?

Thanks.

TauCeti 2004-02-18 10:00

[QUOTE=ixfd64]It seems that Hz are not always the same as FLOP/S...
For example, I've heard that some AMD 2.x GHz processors are faster than the P4 3.x GHz processors...
Is there a FLOP/s specification for processors? Just wondering. If so, where can I find reliable data?
[/QUOTE]

To specify the measuring of the number of floating-point operations per second one has to agree _what_ to measure.

You can measure the theoretical peak rate of common floating point ops like FADD, FSUB, FMUL and FDIV without memory interaction (i think that was the 'original' MFLOP rating).

Or you could agree on a specific workload like solving some equations with [URL=http://pubwww.fhzh.ch/~mgloor/data/linpack.c]LINPACK[/URL] or the [URL=http://www.spec.org/cpu2000/CFP2000/]SPEC CFP[/URL]

Tau

E_tron 2004-02-19 06:44

It is hard to put AMD and Intel's processors side by side with the same measuring system. AMD processors perform FPU operations faster while Intel Processors favor integer. There are more complications like FSB, Stages, ect....

Personally I prefer AMD K7 processors, because they are cheap and perform. Intel P4’s perform too, but their price tag is higher and you are directly support what could become an oligopoly.

aaronl 2004-02-19 09:46

[QUOTE=E_tron]It is hard to put AMD and Intel's processors side by side with the same measuring system. AMD processors perform FPU operations faster while Intel Processors favor integer. There are more complications like FSB, Stages, ect.... [/QUOTE]

I'm not an expert but I believe you've reversed the two. Athlons are known for very strong integer performance. Their FPU is also respectable, but Pentium 4's can be much faster with code that is optimized for SSE2. The best evidence of this is GIMPS performance on Pentium 4s as compared to Athlons.

dsouza123 2004-02-19 14:19

Athlons are faster using the FPU, P4 have a very slow FPU which is why SSE2
instructions that do floating point math are used instead.

The P4 integer unit (for some code) runs at twice the clock speed.

Athlon64s have speed/access issues with SSE2.


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