Author: Tony Werten
Date: 03:02:24 09/16/01
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On September 15, 2001 at 22:34:27, Robert Hyatt wrote: >On September 15, 2001 at 03:28:18, Tony Werten wrote: > >>On September 14, 2001 at 22:56:06, Pham Minh Tri wrote: >> >>>I see that dual computers are expensive, not easy to own and still limited in >>>power of computing. >>> >>>I wonder how good / possible if we use all computers in a LAN for chess >>>computing. LANs are very popular and the numbers of computers could be hundreds. >>>Even though a LAN is not effective as a dual circuit, but the bigger number of >>>processors could help and break the limit. >>> >>>What do you think? >> >>When you search a chesstree, a lot of times you come into parts of tree that you >>have searched before. You either don't want to search this part again ( you have >>searched it deep enough before ) or you want to have the best move from the >>previous search. Hashtables do exactly this. >> >>In a LAN (or a cluster) you don't share this hashtable and therefor are >>searching the same tree (or parts of it ) time and time again. If you count the >>number of nodes searched per second it's a linear speedup but effectively it's >>useless. You have to add a lot of computers before you get any real speedup, >>specially in the endgame. >> >>cheers, >> >>Tony > > >This is not necessarily true. Several programs have distributed the hash table >across network nodes. It requires small changes to the basic search algorithm, >but a distributed hash table is not only doable, it has been done more than >once. > >I will probably do this in the distributed Crafty when I do it... I guess sharing the first x ply on a 1 or 10 Gb network will work, but I don't think you can use the normal dynamic tree splitting. I gues you have to split at a static depth ( decided in the first search ) ? Just to get an impression. How many single Xeons do you think you'll need to get the same speedup you get on a quad Xeon ? After that, does it scale ? cheers, Tony
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