[Samba] performance regression between 30.14a and 3.0.20

[Jeremy Allison]

On Thu, Apr 27, 2006 at 11:53:29AM +1000, James Peach wrote:
> On 4/27/06, Greg Dickie <greg at max-t.com> 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?
> 
> O_SYNC is not a good option to use if you want good write performance
> on XFS.  It's what you use to when you really want your data safe and
> don't care about throughput.

Ok - it's set in smbd when the client sets the create options flag
FILE_WRITE_THROUGH. That was added in the conversion to ntcreateX
code from the old openX code. I expected FILE_WRITE_THROUGH to be
*very* rare - I'll look over lots of traces to check.

I can easily add a check for "strict sync = yes" before setting
that flag. Give me a minute or so....

Jeremy.