AMD bulldozer and GMP

[Vincent Diepeveen]

Rick,

you can prove that throughput of bulldozer is not more than from the  
quadcore intels.
In the end bulldozer decodes 4 instructions a cycle a module and  
intel decodes 4 instructions a cycle a core,
and bulldozer is a tad slower then than the intels as its caches are  
a lot slower.

For parallel well scaling applications that is why bulldozer always  
will lose it from quadcore intels.

Besides - they really overclocked bulldozer a lot to get where they  
are now.

GMP is such a highly optimized software product that integer  
multiplication dominates and i bet in bulldozer
they added huge latencies there in order to overclock bulldozer a lot  
to be at least nearby the intel quadcores.

On Feb 15, 2012, at 12:54 AM, Rick Hodgin wrote:

>> It is totally incomprehensible what AMD is doing.
>> The new processor runs hot, slowly, and hardly
>> outperforms a 5W processor for integer number
>> crunching.  OK, they do, thanks to a 2x clock and
>> a more cores. But clock-for-clock they are equal.
>
> There was a lot of surprise in the CPU community when AMD released  
> its early Bulldozers for internal benchmarking.  The additional  
> cores provided far greater throughput overall, but so much was lost  
> for lesser-parallelized applications that everyone was left  
> scratching their heads and wondering what was going on (as you are  
> doing now).
>
> AMD was also surprised by its performance actually, indicating to  
> many that it was an unexpected condition.  Yet, in the end there  
> were some fixes made but nothing to bring it up to par with what  
> everyone (outside of core development??) was expecting.
>
> Best regards,
> Rick C. Hodgin
>
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