Author: Robert Hyatt
Date: 08:16:27 08/27/02
Go up one level in this thread
On August 27, 2002 at 10:28:09, K. Burcham wrote: > >I am not clear on these questions: > >1. when does a program write to hash? Whenever it completes searching at any particular node in the tree. It tries to save the results of this search so that if the same position arises elsewhere the search can be avoided. Basically one store per node searched, except for the nodes where you get a hash hit to avoid a search, since storing there would be pointless. >2. when does a program write to the hard drive? In my case, at three points: 1. when it does book learning, which is 10 moves out of book. 2. whenever it does "position learning" which happens when a search is completely finished, a move is made, and the score is significantly worse than expected. 3. whenever it displays a PV, because this goes into the log file. But it is _very_ rare. >3. when does a program write to ram separate from the hash? All the time. Updating scoring tables, temp variables, PV stuff, generating moves and sticking them in a move list. Evaluating. You-name-it... >4. If a pc has 512 megs ram, If we set hash at 64 megs, what happens when hash >gets full? Stuff starts getting replaced, even if it might be useful. >5. lets say a program stays in book for 15 moves, is the program accessing only >the hard drive to play book moves? Or Is this info moved to ram first and then >the program plays the book from ram? Depends on the implementation. Some read the entire book in first. Others (myself included) do not so that the book can be far larger than physical RAM. >6. In the middle game after book, I assume this is when the program starts to >store info from analysis. during this period, what is being read/write to the >hard drive before the hash is full? For Crafty, it would mainly be log file info. >7. In the middle game after book, what is being read/write to the hard drive >after the hash is full. same as above. >8. In the middle game after book, if we set the hash at 64 megs, and then this >fills, will the program just use more of the ram, or will it store analysis >directly to the hard drive? Neither. It will just have to replace hash entries by overwriting them. >9. what were programs doing with analysis before hash tables? did all this >analysis set in ram? did the operating system manage this info as needed, and >move the stored analysis to the hard drive as the ram filled? They simply didn't have the hash tables. But this has been around since the early 1960's as Richard Greenblatt was the first to mention the idea and he used it in Mack Hack. >10. if we set up two identical computers, running same program on each. >set up same test position on both. computer A with hash tables and computer B >without hash tables. how do these two compare, what memory are they using and >when. > The main point is that the program with hash tables will search deeper, faster. > >In other words when exactly, will a hard drive speed increase also speed up a >chess program and why? Hard drive speed is irrelevant until you start probing endgame tablebases. Then that speed becomes very important. But otherwise, it can be ignored. > >some will say go study on the internet. i have at many sites. i cannot find >answers to these type of questions. if you know a site that answers these >questions, please let me know, i will go there and study. >thanks >kburcham
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.