Author: Ricardo Gibert
Date: 14:26:48 09/24/03
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On September 24, 2003 at 16:45:20, Sune Fischer wrote: >On September 24, 2003 at 16:31:37, Robert Hyatt wrote: >>"Think outside the box". >> >>the power of 2 is _not_ a memory address. It is a hash table index. If >>an entry is (say) 48 bytes (in Crafty this is true as a single hash probe >>accesses a "bucket" of three entries, one depth-preferred entry and two >>always-store entries.) This means that my hash sizes are 3/4 of a true >>power of two, which is why I use sizes like hash=48M, hash=96M, up to >>hash=768M on my 1gb dual xeon box. >> >>That lets me use 3/4 of memory for hash (transpositions/refutations) and 1/4 >>for the rest of the stuff like pawn hash, egtb cache, and whatever else I have >>in the program. > >Suppose you had only 512 MB, then you would have to choose between 384 MB or 192 >MB. >The 384 might cause swapping and it has to be allocated in one big continues >block might not even be possible, so you'd have to all the way down to 192 MB. > >Compare that to a program which is able to slide right in below the 384 MB, say >350 MB where no swapping occurs. > >-S. How much of an improvement can be expected in time to depth when going from 192 Mb hash to 350Mb hash?
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