Author: Robert Hyatt
Date: 13:44:59 05/05/04
Go up one level in this thread
On May 05, 2004 at 16:28:35, Vincent Diepeveen wrote: >On May 05, 2004 at 11:56:21, Robert Hyatt wrote: > >>On May 05, 2004 at 09:29:19, Brian Kostick wrote: >> >>>On May 05, 2004 at 09:14:50, Mike Hood wrote: >>> >>>>On May 05, 2004 at 08:12:44, Vincent Diepeveen wrote: >>>> >>>>>On May 05, 2004 at 07:47:57, Mike Hood wrote: >>>>> >>>>>>I just let Filemon run while loading Fritz 8 to see why it takes so long. I was >>>>>>shocked to see that during the initialisation Fritz tries to open every possible >>>>>>tablebase. For instance... >>>>>> >>>>>>Open kpk.nbw.emd -- good, it's there >>>>>>Open kpknbw.emd -- file not found >>>>>>Open kpk_nbw.emd -- file not found >>>>>>Open kpk_nbw_emd -- file not found (I never knew this format was valid) >>>>>>Open kpk.nbw -- file not found >>>>>> >>>>>>And the same five accesses for the nbb file. >>>>>> >>>>>>Why carry on with the other three after finding the first tablebase? But it gets >>>>>>even wilder when it comes to the 6-piece tablebases. All 365 possible tablebase >>>>>>pairs in all possible formats are accessed, even though I don't have any on my >>>>>>disk. Thousands of "file not found" results. Just one example, to show how >>>>>>ludicrous it is: >>>>>> >>>>>>First Fritz tries to open krbnkp.nbw.emd, krbnkpnbw.emd, krbnkp_nbw.emd and >>>>>>krbnkp.nbw.emd. Almost the same as before, except Fritz is assuming 6-piece >>>>>>tablebases are compressed. But then Fritz tries to open krbnkp.0.nbw.emd, >>>>>>krbnkp.0_nbw.emd, krbnkp.0nbw.emd and krbnkp.0_nbw_emd. Then krbnkp.1.nbw.emd, >>>>>>etc... and krbnkp.2.nbw.emd... and all the way through to krbnkp.g.nbw.emd. That >>>>>>means 136 disk accesses for a tablebase that I don't have! And that's only one >>>>>>tablebase out of 365. >>>>>> >>>>>>Wouldn't it be much easier just to scan the tablebase directory and only open >>>>>>the files that actually exist? >>>>> >>>>>Both nalimov and i do this in a similar way. >>>>> >>>>>If you are willing to write code for this that works faster and works both for >>>>>windows and *nix, then i will be real happy to use it. >>>>> >>>>>Best Regards, >>>>>Vincent >>>> >>>>Thanks for the info, Vincent. I assumed the initialization code had been written >>>>by Chessbase, not by Eugene. >>>> >>>>My math was a bit off in my original post, but after looking at Filemon's log I >>>>can give the exact figure: Fritz attempts to access 33647 non-existent tablebase >>>>files. And please... you can't tell me that if the file krbnkp.0.nbw.emd doesn't >>>>exist it still makes sense to look for krbnkp.1.nbw.emd, krbnkp.2.nbw.emd, etc >>>>all the way to krbnkp.g.nbw.emd. That's a waste of processor time on any >>>>operating system. >>> >>> >>>Could you report the time from the first tb until the last? I know it will >>>change from system to system but curious just to know how long it takes there. >>>BK >> >> >>About 10 seconds on my box with about 1/2 terabyte of egtbs in use, maybe a tad >>less than 1/2 terabyte.. > >About 3 hours for a 512 processor supercomputer though with 512GB ram and 1 TB >i/o. So? It would take about 1 second on a Cray T932. But how would you know since you didn't have any? More made-up numbers??? I can open all the 6-piece files over NFS in a couple of minutes on my laptop...
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