Author: Stuart Cracraft
Date: 11:12:03 12/28/05
Go up one level in this thread
On December 27, 2005 at 15:35:24, Dann Corbit wrote: >On December 27, 2005 at 13:34:08, Stuart Cracraft wrote: > >>On December 27, 2005 at 04:49:51, Vasik Rajlich wrote: >> >>>On December 26, 2005 at 16:52:23, Jonas Cohonas wrote: >>> >>>>For long analysis that is, i mean if you have an engine running for say 2 days >>>>on a position, will it come to another conclusion whether you use 32Mb hash or >>>>2Gb hash? >>>> >>>>In other words will it, at that time control/analysis matter what hash size you >>>>use? >>> >>>I vaguely remember some tests which suggest that every doubling of the hash size >>>gives 5 or 6 rating points. >>> >>>Vas >> >>Yes - I recall something from Gordon Goetsch and Hans Berliner at CMU quite >>some time ago that gave 2x = 8 rating points. It may have been Carl Ebeling. >>I believe it was the 1970's or 1980's for that figure. And that may have been >>USCF rating points instead of ELO points. >> >>Here is a more recent commentary from 1998 SSDF which gave 4-5 rating points >>per doubling. >> >>http://www.geocities.com/CapeCanaveral/Launchpad/2640/ssdf/1998/ssdf9804.htm >> >>And here: >> >>http://www.chessassistance.com/Articles/020_Hash_size.html >> >>It is no quick way to improved rating unless the table is horribly small already >>of course. >> >>I like to size the table commeasurate with the size of searches I'm doing. Since >>I don't size dynamically but statically at compile time. I am sure most size >>dynamically at compile time for flexibility. I haven't done this yet. > >I think that Shredder benefits from large hash more than other programs. > >I have seen dramatic differences in solution times (much faster) with big hash >(512 MB or larger) compared to smaller hash sizes. Thanks. I need to experiment with larger hash tables and move from statically to dynamically, continually resizing at program startup until I don't get a failure and then take less than that for the malloc() for the hash areas and then use that amount. Right now, I do the allocs but they are based on preset parameters for the # of entries. Dynamic sizing is (I hope) what the commercials do. Stuart
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