Author: Robert Hyatt
Date: 09:16:23 04/16/03
Go up one level in this thread
On April 16, 2003 at 07:49:59, Vincent Diepeveen wrote: >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 Except for critical cases. Such as changing your best root move. Splitting at ply=3 will be bad there in as many cases as it is good. Not splitting at ply-2 there will be bad in as many cases as it is good.. > >>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 >>>> >>>>> >>>>> >>>>>>
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