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Subject: Re: Matt Taylor's magic de Bruijn Constant

Author: Andrew Williams

Date: 09:42:37 07/13/03

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On July 13, 2003 at 12:17:19, Russell Reagan wrote:

>On July 13, 2003 at 07:43:26, Andrew Williams wrote:
>
>>Probably a stupid question, but if you have a loop which does just LastOne with
>>this scheme, wouldn't the table get cached and therefore make it go much faster
>>than in a test where it's embedded in your code?
>>
>>AW
>
>Why would a 64-byte table not be cached in the real run of the chess program?

I always assume that it would be pushed out in the course of all the other
things that the program is doing. I guess it depends on how frequently the table
is used. I don't know anything about bitboard programs, so I couldn't begin to
judge what is happening. One thing I can recommend is valgrind and cachegrind:

http://developer.kde.org/~sewardj/

These seem to be Linux-based tools, but I assume you can get something similar
for Windows. Cachegrind tells you how many cache misses every function in your
program causes. Cachegrind is actually an option to valgrind, so you run
valgrind with a special option to do the cache checking.

Andrew



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