Author: Peter Karrer
Date: 09:37:06 09/19/99
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To reduce the amount of memory needed for generating 6-man tablebases with pawns, couldn't we try to produce them incrementally? First, the tablebases with a pawn fixed on file 7 would be generated, say KxPa7Kyy...KxPh7Kyy. To generate for instance KxPb6Kyy, we would need only KxPa7Kyy, KxPb7Kyy and KxPc7Kyy and so on. One could devise the indexing scheme in such a way that merging these partial TBs would be a simple matter of concatenation. Memory needed for this approach would be more than for 5-man tablebases, but most likely below the treshold where you need 64-bit addressing. Regards, Peter On September 17, 1999 at 12:47:03, Eugene Nalimov wrote: >On a 256Mb machine you must be able to generate all 5-man pawnless TBs. Maybe >you'll be able to generate TBs with pawns, but here I have some doubts - it >looks that paging will slow it down too much. In any case you can try, and if >one iteration will took less than (say) two hours you'll be able to do that. > >I beleive that you can use compressed TBs during generation; just don't use >memory-mapping files (-p), use TB caching (-c <cache amount>). Of course it'll >be slightly slower, but not much. > >Theoretically it's possible to modify the generator so it'll produce compressed >TBs, but I hate to do that. You can try if you wish :-) > >Eugene > >On September 17, 1999 at 10:54:09, Owen Lyne wrote: > >>Continuing to set iup my new Athlon with Crafty, tablebases, Winboard etc. So, >>I'm at the EGTB stage right now. Thought people might be interested in >>speed of generation - did all the 3/4 piece tablebases in about >>90 minutes (Eugene quotes a PII/400 taking about 2 hours, so that >>sounds about right). >> >>Next though is 5 piece, I have 256MB of RAM but Eugene likes >>machines with 500+, so I may have a problem... >> >>Which bases (perhaps pwnless ones?) can I do and which are totally >>impossible with the code set up as it is? Can I try anything and >>just put up wirh ridiculous paging to disk and slow performance, >>or is it not even possible? >> >>Other thought is about compression - being able to run Crafty >>using compressed tablebases is absolutely awesome, and without taking >>a performance hit is astonishing! Great work Bob, Eugene and Andrew Kadatch! >> >>Now - how about generating tablebases, is it possible (either with current code, >>or to modify code so it is) to generate tablebases where the minors >>are compressed? That would be incredibly useful, especially again if it >>was without much performance hit. >> >>It's all very well saying compressed only take 6 gigabytes (I have plenty) but >>If I have to have all 22 gigabytes uncompressed while making them before I can >>compress any then ouch, I don't think I can manage... I presume I could figure >>out which minors are used to generate any one base and carefully compress and >>uncompress accordingly, but directly using compressed minors would be ideal. >> >>One step further, generate in compressed form (I know that's probably even more >>ridiculous, but would hugely help those operating in limited disc space). Of >>course I know the other thing someone with limited space can do is >>download not generate them, but when I got 3 or 4 KB/s to Bob's FTP site >>I knew that wasn't going to be any use for me... Not having to pay >>the phone bill anyway... From work I get much, much faster FTP, but >>via my ISP (Freeserve) and modem looks much slower (maybe time of day >>was also relevant, early morning UK time much better than evening UK time >>since thg latter is daytime in US). >> >>Owen
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