Author: Robert Hyatt
Date: 19:29:49 03/12/03
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On March 12, 2003 at 13:44:46, Bernardo Wesler wrote: >Although I am not an expert in computing, I know that the larger amount of hash >tables you set, the performance of the processor goes down. There is no reason for this, with one exception. The TLB is not very big, holding up to 256 virtual to real page translations depending on the particular processor you have. Once you go beyond this number of unique virtual pages, each memory reference turns into three, two to do the virtual-to-real translation and the third to read the actual data. That can hurt, but since hash probes are random in location, this is probably going to hurt no matter how big the hash, since 256 pages is only 256 * 4K bytes, which is one meg. >I guess there is an equilibrium point between hash tables size and times and >processor speed.... >Which are the best hash tables settings for blitz games (approx. 10'x side)? >I run a 2.0 Ghz processsor, and 700 mb ram, and windows xp prof. >Is this equation the same for fritz, shredder or whichever top chess program? If >not, how does it work ? The idea is to compute the following: time per move * hash table nodes stored per second. The first part is obvious. The last part is not so easy. If a program hashes all nodes, then that nodes stored per second is just the raw nodes searched per second. If a program doesn't hash q-search nodes (Crafty, for example) then you have to figure out what percentage of the total nodes searched are stored, and that is not a constant. I added a new "adaptive hash size" in Crafty so that you simply give it the estimated nodes per second, and the level command to set the time per move, and it will set the hash size pretty optimally. >By the other hand, I want to ask why there are available to be changed , other >parameters settings , for example in fritz, if "they" say the best settings are >the default ones.... and they dont explain (At least at the help files) what >would happen if I change a 10% my queens value or the computers one..... what >would happen if i change the style from agressive to solid, why it would be >weaker.....etc, etc, for the other many parameters..... >Obviuously I dont expect anybody to exp[lain all this stuff in this forum, but >pls, would you be so kind to send me links where i can learn more of this? >Thanks a lot.
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