Author: Bruce Moreland
Date: 21:26:40 01/16/98
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On January 16, 1998 at 22:36:10, Detlef Pordzik wrote: >This sounds remarkable to me, since I haven't such a good education of >the >" what's going on inside ". >As far as I know, and from my own experience, progs like, for instance, >G5 >don't care too much for big hash tables, whilst, for example, R9 fills >up his >maximum capacity of 60 megs quite fast - mostly. >I once had a try with F5 - just to see, if it really was true, and >allowed him 85 megs on my 128 MB system.....full within about 5 minutes >- I simply can't believe, that this is efficient ? >Now to my question : >is there, using W 95, a kinda standard or approx formula, how much hash >to allow the program working on unlimited analysis time, which means, >for example, 8 hours ? >Then, of course, stand alone. - Or is it so - as I would suggest, that >it depends on the prog in the end....and in one's own experience ? A hash table is not like a balloon. If you put too much stuff in a balloon, it explodes. It is not like if you fill up your hash table everything goes bang. It is more like a bucket which you are trying to cram a pile of money into. There's lots of money lying around, bills in huge denominations, and near-worthless coins. You want to have a huge bucket and grab all the money, but with a smaller bucket you may still be mostly OK, because you can fit the large-denomination bills, and you just forget about the least valuable coins. There is (or should be) a priority system for handling cases where there is too much information and not enough storage. I think that in general you want the largest hash table that will cause you not to thrash, although on a slow machine with a lot of memory and a fast time control, perhaps you might use a smaller table with some programs. If you hear your hard disk going like crazy, or get some other indication that your computer is about ready to catch on fire, you can assume that you made the table too big. Make it smaller, quick, if you can still move your mouse around. A program that handles hash tables better (by storing less or replacing things more intelligently) has an advantage over one that does a lot more nodes or replaces less well. It's not a crushing advantage though, unless you really really really care about this stuff. You shouldn't feel like you can't play long games with a program because your computer doesn't have enough memory. Just get as much memory as is appropriate to your level of game playing, word-processor hacking, budget, and level of computer chess fanaticism, and allocate the largest tables that don't thrash (and err on the side of allocating them too small unless the sound of your hard disk chirping soothes you), and have fun. In a couple of years, throw away the computer and get a faster one with more memory for less money. bruce
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