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Subject: Re: Processor's

Author: Vincent Diepeveen

Date: 03:22:04 06/18/04

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On June 17, 2004 at 21:06:51, Jeremiah Penery wrote:

chessprograms in general do not profit going from 512KB to 1MB.

Crafty doesn't either.

www.aceshardware.com proves it doesn't matter for diep either.

>On June 15, 2004 at 06:33:57, David Mitchell wrote:
>
>>Crafty is so cache-stingy, it might not make a big difference, but I'd be amazed
>>if a program like TSCP, wouldn't see a sizeable difference if the L2 cache size
>>was doubled.
>
>TSCP probably fits in any processor's L2 cache, and even the L1 cache of
>Athlons.  So increasing L2 cache size won't help it at all.  Crafty should enjoy
>at least some benefit from increasing the cache size (up to 1MB, or perhaps
>more).
>
>>Of course, I've been amazed before, and nothing beats a little testing - all
>>theories aside, you see the darndest results!
>
>The reason that increasing cache size doesn't increase the speed of chess
>programs is that almost all the memory accesses in a chess program are hash
>probes, which will cause cache miss and must go to main memory, which is very
>much slower.
>If you make the hash table small enough to fit inside the cache, then maybe you
>will see some benefit in terms of NPS from making cache bigger (because you can
>increase hash table size and still be in cache), but your time to solution will
>go up also with the smaller hash table.



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