Trivial(?) reorganization of topology lock in geom_event

[Marius Nünnerich]

On Sat, Dec 6, 2008 at 10:00 PM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
> In message <b649e5e0812041241ja4c3886s526590c98e59f629 at mail.gmail.com>, "=?ISO-
> 8859-1?Q?Marius_N=FCnnerich?=" writes:
>>Hi,
>>
>>while working on the DTrace probes for geom I noticed that
>>g_topology_lock() is called 20 times per second from the g_event
>>thread, even though the thread only runs 10 times per second when
>>idle. Maybe it is possible to change the locking like in this patch? I
>>also changed the position of one unlocking of g_eventlock.
>
> In theory the timeout is not necessary, it was added as a stopgap
> because there were synchronisation issues long time ago.
>
> Try dropping the timeout and see if you can provoke problems,
> if not, kill it.

Did so, please take a look at this patch:
http://nuenneri.ch/freebsd/geom_tl2.patch

I am running a version of this with the DTrace probes included, I hope
the patch is complete.
I did a few buildkernels and some of the geom regression tests, so far
no problems.
I changed the position of the loop to better match how it's like in
the up and down threads.
What do you think of it?

Thanks
Marius