Tom Lane wrote: > Bruce Momjian <[EMAIL PROTECTED]> writes: > > _That_ is an excellent point. However, do we know at the time we open > > the file descriptor if we will be doing this? > > We'd have to say on a per-read basis whether we want O_DIRECT or not, > and fd.c would need to provide a suitable file descriptor.
OK > > What about cache > > coherency problems with other backends not opening with O_DIRECT? > > If O_DIRECT introduces cache coherency problems against other processes > not using O_DIRECT then the whole idea is a nonstarter, but I can't > imagine any kernel hackers would have been stupid enough to allow that > to happen ... Seeing how the buffer exists in user space, I would be interested how they prevent coherency problems with good performance --- maybe they map the same page into multiple processes --- that would be interesting, though it would require some locking. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster