Author: David Dory
Date: 05:37:59 10/18/02
Go up one level in this thread
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. > >Another question: Is it possible the determine the actual amount of >physical RAM that is installed in the machine? > >-- >GCP Win2K sets the cache size (of the offline disk cache) to equal 10% of the size of the hard disk that has Win2k on it, as default. This is the only cache mentioned in my Win2k book "Running Windows 2000 Professional" by MS. You may adjust this disk cache by going into control panel, and then selecting "Folder Options", then go to the tab "Offline Files". At the bottom of the window, you'll see a slider that can be adjusted as high as 100% of the drive (however wacky that might be). Perhaps your offline file cache setting is about 16M ? Another performance option is the virtual memory setting. Again, go into control panel, select "System", and the "System Properties" window will pop up. At the bottom of it, it will tell how much RAM is in the system, in KB. If you select the "Advanced" tab, and then click on "Performance Options" button, it will then show you the vm paging size for all drives, in total. If you then click on the "change" button, you will see the virtual memory sizes for all individual drives. For best performance, keep your virtual memory size at least the recommended size that the window now shows for "recommended size". You may want to try the largest size, also. If you have multiple drives, you should have a paging file on each one for best performance, this allows each to be accessed simultaneously by the disk controller. The window mentioned above also shows the settings in the registry, strongly suggesting they can be changed by editing same, but I have no experience with changing it through the registry. I have sorted 30,000 plus FEN strings in the blink of an eye with Win2k on a laptop with 512Ram and a 1.86Gig offline cache setting. Very impressive. Be glad to try your bookbuilder with these settings, if you like. David
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