Author: Robert Hyatt
Date: 06:41:29 09/16/01
Go up one level in this thread
On September 16, 2001 at 06:02:24, Tony Werten wrote: >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 ) ? That is not my intent. Of course, I won't try to split at the deep levels in the tree that I split at now. But for (say) the first 1/3 of the plies in the current search, splitting is certainly doable. This will just be a tunable parameter that will have to be adjusted depending on the hardware and network speeds. > >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 ? I can't imagine that this will be less than 50% effective. Or, if we take deep blue as an example, no less than 30% effective. I would think that 8 cpus would be very close to the quad... > >cheers, > >Tony
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