Author: martin fierz
Date: 12:07:52 10/18/02
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On October 18, 2002 at 06:54:58, Gian-Carlo Pascutto wrote: >Since I've rewritten Sjeng's bookbuilder, I've noticed something >strange. When I build books on Linux, the bookbuilder runs at >a constant speed of several hundred games per second no matter >how large the book is. > >On Windows 2000 however, performance falls steeply to a tens >of games per second as soon as the size of the book gets bigger >than (approximately) 16M. > >The natural explanation seems to be that Linux has no problem >caching the entire book in RAM (>600M RAM free) so building happens >essentially with disk access only to read the PGN. > >Windows doesn't seem to be able or willing to cache more than 16M >of the book and starts writing to disk to soon. > >Some questions: > >a) Does the same effect still exists in Windows XP or is it fixed there? >b) Can my application give 'hints' to the OS via system calls to avoid this? >c) Is there any way to fix this possibly via editing the registry? > >If there's no satisfactory solution, I'll likely add more caching in >my bookbuilder, but it seems silly that a modern OS cannot handle this. while i generally agree with your last statement, the OS can never know quite as well as the programmer what it should or should not be caching. so for best performance it's generally a good idea to do the caching yourself if you know it's necessary. also, i wonder a bit what your bookbuilder does, why do you need disk caching at all? shouldnt you just be reading each game in the database just once? aloha martin >Another question: Is it possible the determine the actual amount of >physical RAM that is installed in the machine? > >-- >GCP
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