Author: Bas Hamstra
Date: 12:10:38 06/13/02
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On June 13, 2002 at 11:09:09, Robert Hyatt wrote: >On June 12, 2002 at 14:35:06, Bas Hamstra wrote: > >>On June 12, 2002 at 11:33:19, Robert Hyatt wrote: >> >>>On June 12, 2002 at 10:59:16, Bas Hamstra wrote: >>> >>>>Currently I use Nalimov tablebases in uncompressed format. Now I have seen you >>>>can compress into emd format. Is it possible to use them directly in that >>>>format? If so, how? >>>> >>>>Best regards, >>>>Bas. >>> >>> >>>The code Eugene supplies (on my ftp site) does this. In fact, it is one of >>>two major innovations Eugene produced (on-the-fly decompression that is very >>>efficient along with the very efficient indexing scheme that reduces the file >>>sizes significantly prior to compression)... >>> >>>His code will recognize compressed or uncompressed tables and use either. >> >>Bob, 2 questions. How bad is the perfomance loss compared to uncompressed? And >>can the 4 man tables be loaded in RAM in compressed form? >> >>Thanks, >>Bas. > > >Unless you have very fast SCSI disks, using compressed tables is _faster_ than >using uncompressed tables. It reduces the total disk I/O demand since reading >a block of compressed data is cheaper than reading a block that is not >compressed. > >When I tested this way way back, using 10K rpm 160mb/sec scsi drives, not >compressing was between 5-10% faster. But for slower SCSI drives and all IDE >drives at the time, compressed was significantly _faster_... Very interesting, found "tbdecode.h" at your ftp. Last question: wouldn't the 4 man tb be even a lot faster if loaded in compressed form in RAM? If so, why isn't that possible (as I am told)? Best regards, Bas.
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