On Fri, Nov 5, 2010 at 23:10, Greg Smith <greg@xxxxxxxxxxxxxxx> wrote: >> Not having a real O_DSYNC on linux until recently makes it even more >> dubious to have it as a default... >> > > If Linux is now defining O_DSYNC Well, Linux always defined both O_SYNC and O_DSYNC, but they used to have the same value. The defaults changed due to an unfortunate heuristic in PostgreSQL, which boils down to: #if O_DSYNC != O_SYNC #define DEFAULT_SYNC_METHOD SYNC_METHOD_OPEN_DSYNC #else #define DEFAULT_SYNC_METHOD SYNC_METHOD_FDATASYNC (see src/include/access/xlogdefs.h for details) In fact, I was wrong in my earlier post. Linux always offered O_DSYNC behavior. What's new is POSIX-compliant O_SYNC, and the fact that these flags are now distinguished. Here's the change in Linux: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6b2f3d1f769be5779b479c37800229d9a4809fc3 Regards, Marti -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
