Author: Robert Hyatt
Date: 10:21:27 09/03/03
Go up one level in this thread
On September 03, 2003 at 10:51:56, Vincent Diepeveen wrote: >On September 03, 2003 at 10:44:11, Sune Fischer wrote: > >>On September 03, 2003 at 10:35:11, Gian-Carlo Pascutto wrote: >> >>>On September 03, 2003 at 10:26:19, Sune Fischer wrote: >>> >>>>>What is your point? >>>> >>>>Heh :) >>>> >>>>You said (remote) checking for fail_high conditions at every node was required, >>>>and I disagree. >>> >>>I never say 'at every node'. >> >>You said constantly, then I don't know what you mean by that. >> >>>Each time you get a subtree score, you must send out the score update to >>>all processors, or store it locally and rely on remote processors to check >>>it in your memory. >>> >>>Either way, you need remote accesses. >>> >>>Got it now? >> >>This is an entirely different matter, you don't get subtree scores "constantly". >>And I still say you only have to access when there is something to communicate. >> >>If you just quietly exit the subtree on a fail low, I see no need for >>communication. > >And how big is your search going to be. 10 ply minimax? > >Or do you prefer 10 ply alfabeta + nullmove. > >How many times is your processor going to check whether he is doing work for >nothing? > >Each node? >Each 10 million nodes? > >The advantage of each node is that it won't idle too much. >The advantage of each 10 million nodes is that you don't eat up bandwidth, but >that your search will be as bad as a single cpu. > >So how are you going to do it? Just like I do it in Crafty. Each "split block" has a "stop" flag that starts at zero. When a processor does a search and finds that other processors are doing useless work because we just found a fail-high at a split point on this processor, I just set all the "helper" process "stop" flags to 1 and then I clean up and return. The other threads will see that stop after searching one node and they exit instantly. I don't have to wait for them to exit, but I can't get them busy helping me anywhere else until they do. This is not hard to solve. >>-S. >>>-- >>>GCP
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