Author: Vincent Diepeveen
Date: 19:48:41 09/15/01
Go up one level in this thread
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... At a 100mbit network i tried to ship 16 bytes packet as fast as possible from a node to another node. I managed to do that with a CROSS-UTP cable about 3000 times a second. That means in short that without counting the 60ms receiving delay in linux, 30ms in windows or something, that you can only ship and get a hashtable entry at 1500 times a second. so unless you want to create a deep blue crafty where you only hash the first so many plies, then you sure will slow down crafty a factor of say 450? How big is your cluster then to get a speedup of over 1.0 ?
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.