process shared robust mutexes for tdb

[Volker Lendecke]

On Sat, Jan 12, 2013 at 10:45:57AM +0100, Volker Lendecke wrote:
> Hi!
> 
> On Sun, Jan 06, 2013 at 07:18:00PM -0500, Ira Cooper wrote:
> > Can you run the same test with 1 bucket?  Not that we'd actually want to
> > deploy that way, but, the performance of fcntl TDB shouldn't drop that
> > much... and it'd give us an estimate of how much we need the 2048 locks vs.
> > just using 1.
> 
> Under the usual branch
> 
> https://git.samba.org/?p=vl/samba.git/.git;a=shortlog;h=refs/heads/tdb
> 
> Now find a patchset that survived autobuild for me. It
> contains some additional stuff, like a tdb feature flags
> field. This could for example take a flag for a dual-linked
> freelist and other future improvements.
> 
> This is something that I would like to see broader testing
> and review of. Getting rid of the fcntl locks in tdb was
> something I have wanted to do for a very long time, and
> while this is not complete it is a start in that direction.

The above branch now contains code that has survived testing
in a cluster with thousands of clients. The cluster survived
a recovery just fine, something which was entirely
impossible due to the fcntl thundering herd before. The fact
that unmodified ctdb is happy with it shows that the API is
covered pretty completely.

I squashed all the patches into one. In the end, I had
almost 100 unsorted patches, no way to sort them into a sane
order.

Comments?

Volker

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