serverid(s)_exist, critical path work.

[Volker Lendecke]

On Thu, Feb 07, 2013 at 07:55:42AM -0500, Ira Cooper wrote:
> On Thu, Feb 7, 2013 at 7:07 AM, Volker Lendecke
> <Volker.Lendecke at sernet.de>wrote:
> 
> > On Thu, Feb 07, 2013 at 06:13:31AM -0500, Ira Cooper wrote:
> > > >From Andrew Bartlett's review on IRC:
> > >
> > > Why remove TDB, isn't that a step backwards?
> >
> > To be honest, right now I'm in the mood to see this actually
> > a step forward. fcntl sucks so badly that I would call it
> > unusable. I am really ripping out my hair right now to
> > replace it with something sane, although that turns out to
> > be much more difficult than initially expected :-(
> 
> 
> 
> The gap TDB fills must be filled by "X".  The general comment is sound, the
> specific instance... well... I wrote the patch.
> 
> Also note, I view what I'm doing as an "index" here, all the real data is
> on the side, this is to speed up one very hot function.  The general
> function of serverid.tdb should not be impacted.

True. I just have my little tdb/fcntl-blues. I had thought
that unix domain datagram sockets are really scalable, but
that also seems not to be the case. My tests on FreeBSD and
modern Linux also gave problems.

So it seems that the only really scalable IPC mechanism
(scalable in terms of many, many thousand instances of
*something*) seems to be epoll and its cousins on other
OSes. I wonder if we can build something fast and robust
upon those.

Commenting on your patch: In theory, the load on
serverid.tdb should be a lot less in master, as we do not
look up every process anymore when reading a share mode
record. We only do it when we have a conflict. I would be
curious if this patch has a big effect when tested with
master.

Volker 

-- 
SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen
phone: +49-551-370000-0, fax: +49-551-370000-9
AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen
http://www.sernet.de, mailto:kontakt at sernet.de

**********************************************************
visit us at CeBIT: March 5th - 9th 2013, hall 6, booth E15
all about SAMBA and verinice, firewalls, Linux and Windows
free tickets available via email here : cebit at sernet.com !
**********************************************************