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.


> > 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                        |
  [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

Reply via email to