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Old 2007-10-31, 11:55   #10
cheesehead
 
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"Richard B. Woods"
Aug 2002
Wisconsin USA

22·3·599 Posts
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Right.

BTW, whenever there's reference to Prime95/mprime/LLR stressing your system or fully using the CPU, what's usually really meant is the part of the code that does Fourier transforms to perform huge multiplications. That's the main work in Lucas-Lehmer, P-1, ECM and LLR; it keeps the FPU pipelines and memory busses (when the number sizes are in tens of millions of bits, they get bigger than most memory caches and have to be circulating out of and into main memory much of the time even though George's code does as much crunching as possible on each part in the cache before sending it back to main memory to make room for the next cacheload) very busy. Other parts of the code, such as trial factoring, use less circuitry because they're not doing Fourier transforms (or at least not as much) or else all the data fits in cache.

Last fiddled with by cheesehead on 2007-10-31 at 12:19
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