[Samba] performance regression between 30.14a and 3.0.20

[Greg Dickie]

Actually it was my much smarter colleagues that found this, I'm just the 
mouth ;-)

Thanks for looking at this, I'll check out SAMBA_3_0 when I get back!

Greg


Jeremy Allison 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).
>
> We have an option "strict sync" which if unset allows us
> to ignore these calls - I've just added it into the ntcreate
> open path so we don't set O_SYNC unless "strict sync" is
> set.
>
> Please check out SAMBA_3_0 and test - this will be in the
> next 3.0.23 pre-release.
>
> Jeremy.
>