Author: Yakov Konoval
Date: 04:16:26 08/30/05
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Hi, Vincent ! On August 29, 2005 at 15:36:08, Vincent Diepeveen wrote: >>>how many entries does your indexing scheme use for one of those >>>files KRBNKRB? >> >>462*(64^5)/2 > >In diep format it's 462 * 62 * 61 * 60 * 59 * 58 = 358752350880 >Versus your format is half of 462 * 64^5 = 496068722688 > 1. 334 GB is not half but 72% from 462 GB 2. Calculations for 462 GB format are much faster and compression is much better. Maybe you will be surprised about the size of uncompressed EGTs for the FEG-generator - it is 10*64*64 etc., but the size of compressed EGT is less then the size of compressed Nalimov's EGT (but also there are another reasons for that). I think, that the only advantage of the 462*62*61 etc. format maybe 28% economy of the RAM. >Without pawns it's easy to calculate it by hand. With pawns it's >very hard to calculate it by hand as i must look it up in the table >first because a king on a1 gives other pawnreduction than king on b2 :) > >So if i understand well, uncompressed the 4 files are nearly 1T entries, >when you would use 1 byte per entry. Probably you had no other option than >that from speed viewpoint as otherwise you can't see so many positions per >second on average. I calculated your generator gets like 30 million >positions per second, when also counting the lazy evaluated ones. This is >very impressive! > >Note in the last generator i build (i built 3 generators over the time) >it is using also a different format than the diep WDL egtb's is using, >because working with 64 possibilities goes a hell of a lot faster, for the >same reason. It's basically cpu speed that is needed. A small disk array >of 8 harddisks and a 4ware raid card already gives at raid0 like 400MB per >second which would support speeds of up to several hundreds of millions of >positions per second. > >I assume you used raid0 for both harddisks? > >If not your generator speed might be quite some faster when adding some array >speeds. Because a single IDE can get a throughput of at most like 50MB/s, >which at 1 byte per entry would be 50 million positions. Now Marc don't use raid0. This raid0 will be very useful and the generation may be faster. (But I think that the real speed will be less than 400 MB/sec). > >Note in diep generator format i use 1 bit per position at generation time. > >>>how many bytes (or bits) per entry did you use at generation time? >> >>Only a few bitmaps for a subset of the 462 king-king positions are in memory >>during generation. 1 bitmap for 19 different king-king positions, plus two >>additional bitmaps for a given king position. A general 7-man endgame thus >>requires 21 * 64^5 / 8 = 2.8 GB of RAM. With permutation symmetries or bishop >>parity tricks this can be reduced accordingly. >> >>We'll give more details in a technical paper we are working on. > >No need, really, your posts are really appreciated on this matter. > >Keep doing the good work! Thanks ! > >Oh, i hardly dare to ask as someone who has everything privateware himself, >but is your resulting EGTB downloadable somewhere? It's a big problem due the huge size of EGTs. Regards, Yakov.
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