Author: Robert Hyatt
Date: 08:09:09 06/13/02
Go up one level in this thread
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_...
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