site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com As a backup utility, you are probably reading a lot of files; as Brian notes if you apply the F_NOCACHE fcntl to these files immediately after opening them, you will avoid evicting other applications' pages in favour of file cache pages. If you do the F_NOCACHE thing, try to meet the following criteria: o page align your memory buffers <x-man-page://3/valloc> o make them an even multiple of the page size <x-man-page://3/getpagesize> o read at an offset into the file that's an even multiple of the page size o read an even multiple of a page size bytes (except at the end, of course) Share and Enjoy -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Relations, Developer Technical Support, Core OS/Hardware _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... At 14:53 -0700 30/5/07, James Bucanek wrote: Michael Smith <mailto:drivers@mu.org> wrote (Wednesday, May 30, 2007 12:36 PM -0700): I hadn't thought of that, and that's an excellent suggestion (thanks also extended to Brian and Matt). By doing all of the above, you increase the effectiveness of F_NOCACHE (that is, your minimise the amount of caching). This email sent to site_archiver@lists.apple.com