Author: Dann Corbit
Date: 19:05:11 12/19/03
Go up one level in this thread
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. The curve looks like c0*log(c1*x+1), where c0 anbd c1 are constants and x is hash size. Y is performance increase. Stupendous at first, and never goes away, but the added strenght becomes less and less. You can make too large of a hash table if you clear hash frequently (e.g. between moves) and the hash clear time becomes significant.
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