# Computer Chess Club Archives

## Messages

### Subject: Re: is the

Author: Komputer Korner

Date: 08:34:39 08/05/98

Go up one level in this thread

```On August 04, 1998 at 13:37:00, Tom Kerrigan wrote:

>On August 04, 1998 at 11:02:17, Komputer Korner wrote:
>
>>The point is that Tom Kerrigan wants proof that hash tables will improve a
>>program by 50 points or a doubling in overall speed. I say they will but he
>
>Yes, I do.
>The rule of thumb is that doubling speed gives you 50 points. This is for
>tournament time controls, but it's the best we can do for now.
>Here's the experiment: take an average computer (say, a PII/266) with 64 MB RAM
>and use a popular program (Fritz, maybe?) to analyze a few positions overnight.
>Then increase the RAM to 128 MB and repeat. Use the largest hash tables possible
>with each amount of RAM. Use positions that somebody would want to analyze
>overnight, too. Perhaps positions from tournament games at crucial points? Be
>sure to have a fair distribution of middlegame and endgame positions.
>
>Cheers,
>Tom

This is only going to tell us the speedup available up to 128 Mb of RAM which
isn't enough. The hash table will get filled up too quickly and even with a good
hash replacement strategy, there still will be a significant slowdown in the
search. For overnight analysis we need 2Gb of RAM and a slow searcher like
Hiarcs or CSTal. Fritz is too fast for this experiment. What we need to do is
run the positions with hash tables until the hash table fills  with successive
increasing amounts of hash tables until you reach 2Gb of hash tables. Each
experiment is to be run until the hash table is filled on each position and then
rerun the same position without hash tables. Check the number of nodes/ply depth
reached. Each program and machine combination will be different of course. Make
sure that  the 2 scenarios are on a representative mix of endgame and middlegame
positions. Are there any slow programs that can accomodate 2Gb of hash tables.
Are there any machines that can accomodate 2Gb of RAM?
--
Komputer Korner

```