On Sun, Feb 9, 2014 at 5:03 PM, Richard Hipp <d...@sqlite.org> wrote: > On Sun, Feb 9, 2014 at 5:49 PM, James K. Lowden > <jklow...@schemamania.org>wrote: > I suspect that adding msync() calls would wipe out any speed advantage for > using memory-mapped I/O. And since speed is the only advantage to memory > mapped I/O and because there are many disadvantages, I don't see a use-case > for trying to make mmap work on OpenBSD.
msync() with MS_SYNC will definitely destroy performance, so don't do that. msync() with MS_ASYNC and/or MS_INVALIDATE are generally no-ops when the OS and *filesystem* implement a shared cache. The extra cost here, then, is the cost of a system call (plus whatever work has to be done to determine that the call is a no-op). Nico -- _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
