Author: Vincent Diepeveen
Date: 09:43:26 04/16/03
Go up one level in this thread
On April 16, 2003 at 12:16:23, Robert Hyatt wrote: >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.. > you can predict that better than for the root. > > > >> >>>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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