Bottleneck with Winbind and NT ACLs in 2.2.7a

[jra at dp.samba.org]

On Tue, Feb 04, 2003 at 02:12:29PM +0100, Michael Steffens wrote:
> Hi,
> 
> we are running a big Samba 2.2.7a server with Winbind (>100 concurrent
> users, >600 id mappings created since then) since last weekend.
> 
> It's running quite well! :)
> 
> However, users are complaining about Samba being very slow when
> NT ACL support is enabled. I'm suspecting that winbindd is the
> bottleneck.
> 
> In winbindd's log I can see that it has to serve "[ug]id to sid"
> requests at a very high frequency. Most of them seem to be triggered
> by smbd daemons working on POSIX ACLs, and the UIDs and GIDs
> requested are almost always those of the user running a session.
> Requests are keeping winbindd busy all the time. And when winbindd
> is busy talking to DCs, user sessions have to wait for ACL settings
> to complete.
> 
> As the ID mappings are static - as soon as they exist - wouldn't it
> be a good idea to have smbd cache those it has come across in the
> current session?
> 
> In the attached patch I have tried to implement such a local
> mapping cache for smbd. What do you think about it?

Damn good idea ! I think I'll look into applying some version
of this - thanks !

Jeremy.