Author: Tony Werten
Date: 00:39:36 04/16/03
Go up one level in this thread
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. 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 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.