Author: Ulrich Tuerke
Date: 03:17:50 12/20/03
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On December 19, 2003 at 21:07:40, Uri Blass wrote: >I am interested if programmers can do the following experiment. > >Take the GCP test suite(delete endgame positions from it) and test your program >twice. > >one time with 1 mbyte hash tables and one time with 2 mbytes hash tables. > >of course 2 mbytes is better but the question is if 2 mbytes gives 6-7% speed >improvement for all problems (except easy problems that are solved in less time >that is needed for the program to fill the entries of 2 mbytes hash table) or if >it gives bigger improvement for hard problems that the program needs some >minutes to solve. > >I asked to use very small hash tables in order to enable programs to fill the >hash tables in a very small time. > >I agree that bigger hash table probably means better branching factor at the >time that is enough only to fill the small hash and not enough to fill the >bigger hash but the question is what happens later. I would rather expect, it's something like a logarithm. Most important is to have a hash table at all. The early Mephisto machines had proven that 32K hash table is already good for an enormous speed-up in pawn endings. However when to consider switching from 2 GB hash tables to 4 GB for instance, I would suggest to use the additional memory otherwise. Otoh, the time control has to be taken into account too. In case your engine analyzes a position for a few days, a very large hash table may be useful. Uli > >Uri
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