Hyperactive g_event thread

[Alexander Motin]

Marius Nünnerich wrote:
> On Tue, Jul 27, 2010 at 18:07, Marius Nünnerich <marius at nuenneri.ch> wrote:
>> On Tue, Jul 27, 2010 at 16:38, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
>>> In message <4C4ED619.7050305 at FreeBSD.org>, Alexander Motin writes:
>>>> Poul-Henning Kamp wrote:
>>>> I have already removed alike timeouts on up/down threads and it indeed
>>>> was safe there. But are you really sure about this specific case? Cause
>>>> I'm not. Up/down threads using msleep and checking lack of work after
>>>> dropping/grabbing lock. Event thread instead does several tasks, drops
>>>> lock few times between them and uses tsleep(). I would say there should
>>>> be a bunch of race conditions.
>>> Quite likely, I didn't say it would be a trivial thing to remove
>>> that workaround :-)
>>
>> I was running with a patch that removed the timeout for a while like 2
>> years ago. Albeit not with high load. Worked fine at that time, I will
>> search for the patch when I'm back home later today.
>>
> Here it is:
> http://lists.freebsd.org/pipermail/freebsd-geom/2008-December/003200.html
> The mail is quite old now, I don't know if the patch still applies.
> Will check that if I can find the time. I would be happy to see this
> committed after all this time :)

Yes, I was thinking about something like that. Patch mostly applies now
and even builds. May be I would just put there sx_sleep() instead if
msleep(), as topology_lock is sx.

Could somebody to review this and tell how correct is to not drop
topology lock between events handling and could there be places where
g_wait_event woken without holding topology_lock?

-- 
Alexander Motin