Author: Vincent Diepeveen
Date: 04:49:59 04/16/03
Go up one level in this thread
On April 16, 2003 at 03:39:36, Tony Werten wrote: >On April 16, 2003 at 00:07:21, Robert Hyatt wrote: > >>On April 15, 2003 at 04:54:11, Tony Werten wrote: >> >>>On April 14, 2003 at 17:43:12, Robert Hyatt wrote: >>> >>>>On April 14, 2003 at 17:15:41, Vincent Diepeveen wrote: >>>> >>>>>On April 13, 2003 at 22:39:39, Robert Hyatt wrote: >>>>> >>>>>>On April 13, 2003 at 11:49:28, Vincent Diepeveen wrote: >>>>>> >>>>>>>On April 13, 2003 at 11:27:53, Robert Hyatt wrote: >>>>>>> >>>>>>>I said initially. It drops back to 10 splits a second in DIEP after a while. >>>>>>>Search depth matters. >>>>>>> >>>>>>>Let's compare 2 things. >>>>>>> >>>>>>> time=45.98 cpu=464% mat=0 n=37870294 fh=88% nps=823k >>>>>>> ext-> chk=638414 cap=249442 pp=9588 1rep=32966 mate=223 >>>>>>> predicted=0 nodes=37870294 evals=14565859 >>>>>>> endgame tablebase-> probes done=0 successful=0 >>>>>>> hashing-> trans/ref=28% pawn=93% used=28% >>>>>>> SMP-> split=431 stop=57 data=6/64 cpu=3:33 elap=45.98 >>>>>>> >>>>>>>MT 2 crafty 18.10 which i have here. 431 splits at 45 seconds. I guess you must >>>>>>>limit in crafty the number of splits a lot as splitting is expensive in crafty >>>>>>>when compared to the costs of a single node. >>>>>> >>>>>>I'm not sure how expensive it is compared to a node. I'll run a test where >>>>>>I do the split overhead at every node to compare, however... >>>>>> >>>>>> >>>>>> >>>>>>I don't limit them at all. The only limit is the YBW algorithm. But I split >>>>>>at the root also, which reduces them signficantly... >>>>> >>>>>I can split at the root nowadays, but i have turned it off for diep. it gives >>>>>too poor speedup for me. The interesting thing which searching SMP can give is >>>>>transpositions at a big depth which possibly are overwritten by a sequential >>>>>search. i don't want to miss them. >>>> >>>>Maybe you don't split at the root correctly. I limit this with some intelligent >>>>guesswork, so that if it appears that I might change my mind this iteration, >>>>then >>>>I don't split at the root until I have searched all moves that I think might >>>>replace >>>>the best move... >>> >>>Just trying to understand. Are you talking about the case where the best move in >>>the root got a fail low ? >> >>No. I search the first move with all processors for obvious reasons. I search >>the next "N" the same way, where "N" is set by trying to figure out how many >>moves _might_ become a new best move (I discover this by looking at the node >>counts for each move after an iteration ends. If any are close to (or bigger >>than) the node count for the first move, then they deserve special parallel >>searching one at a time, before I split at the root and search a root move >>with only one processor (which will take longer). > >Hmm, I thought I finally understood this crap. Isn't splitting at the root the >most desireable situation ? If you have (after bestmove) 2 moves that deserve >special attention, why not search them parallel. Most of the time they will not >give a failhigh anyway. Ideal for the PV is splitting at realply == 2 and ideal for all non-pv moves is doing parallel search at realply == 3. Best regards, Vincent >Tony > >> >>> >>>When that happens, your testresults indicate that's it's better to split lower >>>than to search 2 rootmoves parallel in order to get an established score asap ? >>>( So not breaking off seacrh when 1 gets a first failhigh, but only when the >>>score is resolved ) >>> >>>Tony >>> >>>> >>>> >>>>>
This page took 0.01 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.