Author: Sune Fischer
Date: 02:21:23 04/26/02
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On April 26, 2002 at 03:01:01, Odd Gunnar Malin wrote: >>> hash table sizes >>>time bytes entries nodes searched >>>------------------------------------------- >>>13:13 96kb 6K 157,085,451 >>>12:03 192kb 12K 142,633,162 >>>10:31 384kb 24K 123,762,238 >>> 9:28 768kb 49K 110,838,220 >>> 8:38 1.5M 98K 100,802,339 >>> 7:48 3M 196K 90,979,000 >>> 7:22 6M 392K 85,975,960 >>> 6:53 12M 800K 80,347,212 >>> 6:32 24M 1.5M 76,465,119 >>> 6:22 48M 3.0M 74,738,532 >>> 6:13 96M 6.0M 73,253,374 >>> 6:05 192M 12.0M 71,581,397 >>> 6:03 384M 24.0M 71,156,722 >>> >>> >>>So about 12 doublings in size give a speedup of slightly over 2. That's not >>>such a huge amount. :) >> >>Thenks for the information. >>It suggests that 6-7 elo from doubling the hash size is really close to the >>truth. >> >>There is a big difference between 6K and 24M but there is not a very big >>difference between 6M and bigger hash tables and in my case I guess that there >>is not very big difference between 8M hash for chezzz and bigger hash tables. >> >>Uri > >You are probably right. Dennis M. Breuker did a test with several different >replacement scheme in his 'Ph.D. thesis: Memory versus Search in Games' and >found out that the gain start with much gain but begin to level out around 512K >entries (If 1 entry=16byte, 16*512K=8M) and at 1024K or before the gain is only >3% for each doubling. >Ref: http://www.breuker.demon.nl/thesis/index.html , Chapter 2, page 35. >This is for midlegame positions. > >Most gain from transposition tables is in the endgame, but here just a little >table would gain many plies, so that the curve is maybe even more precipitous >for endgames. > It would interesting to see, if these numbers stay the same when the hash is not reset before every search. I do not reset the hash and can therefore use information found in previous searches, I think the information found 3-4 moves ago can still be used if the hash is big enough. I don't know if this is a big factor. -S.
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