Author: Uri Blass
Date: 09:31:40 12/03/05
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On December 03, 2005 at 11:56:42, Andreas Guettinger wrote: >On December 03, 2005 at 11:01:46, Paul Jacobean Sacral wrote: > >>I would appreciate a couple of clarifying remarks as well, because this is a >>topic that's difficult to understand if you are not a progammer. Bacically, I >>was studying explanations of this in the past but didnt't understand all of it, >>and also do not remember all of it. >> >>My question is: >> >>How come that some solving times of test positions are worse (longer) with >>bigger hash tables, than with smaller hash tables? >> >>Yours truly Paul J. Sacral > >Can you give an example? >The size of the hashtable should not make a considerable difference in solving >time, except if the engine clears the hashtable in analysis mode at the >beginning of the search, which could take 1 or 2s on slow hardware. (Note during >normal gameplay hastables usually don't get cleared.) >Per position (in the search tree) it takes normally 1 (written ONE) probe per >hashtable, doesn't matter if the hashtable is 1Mb or 1Gb. >As a banal example, if you have a file register in your office, and you want to >lookup file no. 56, it doesn't mater if you have 100 or 1000 files stored, you >just walk to the shelf and take file number 56. > >regards >Andy some points 1)more hash do not help in every position and it is possible that some position is going to be solved faster with less hash because of luck. 2)more hash does not help to every engine even if we talk only about long time control and at least in the case of Movei more hash seem to be counterproductive in case it is too much. The problem is that the type of history based pruning that I use may be less correct with more hash. I believe that more hash can be productive with changing my history based pruning but I think that no programmer should assume that more hash is always productive without testing(espacially programmers who use tricks like history based pruning). Uri
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