[Samba] performance regression between 30.14a and 3.0.20

[James Peach]

On 4/27/06, Jeremy Allison <jra at samba.org> wrote:
> On Wed, Apr 26, 2006 at 01:20:23PM -0400, Greg Dickie wrote:
> > OK all my gobbledy-gook stats aside..... sorry for being incoherent.
> >
> > Stracing reveals that files after 3.0.20b are opened with O_SYNC. Could
> > that be the source of the problems? I'll try and find that and test it
> > when I get home but the question is is it necessary?
>
> Greg - I LOVE YOU :-). That's almost certainly the problem.
> Back in the Win9x protocols days (the openX style of calls)
> we had the problem that Windows clients were setting the
> "sync this data" flag for almost every open - completely
> unneccessary. For 3.0.20x we changed to the NTcreateX
> style of open, and mapped the create option FILE_WRITE_THROUGH
> to the O_SYNC. I bet the Windows redirector in W2K, XP and W2K3
> is just as dim, and is adding that on almost every open (I'm
> on a plane right now so can't get to my vmware sessions
> easily to check).

xdd explicitly sets this flag when it calls CreateFile. Testing with a
different windows dd program gives more expected results.

--
James Peach | jorgar at gmail.com