taskqueue for pf periodic events

[Max Laier]

Gleb,

On Tuesday 07 March 2006 11:59, Gleb Smirnoff wrote:
>   running a pf load balancer I have noticed that the "swi4: clock"
> process consumes a noticable amount of CPU time, when a lot of
> states are purged from pf cache. The load balancer is also running
> CARP, and a hot spare is working here too. Reading daily run outputs
> from the second router, I have noticed that a few times per day
> the redundant router preempts the main one, since it doesn't
> receive announcement in time from master. So, I had a theory that
> a heavy pf purge is running so long, that a CARP announcement
> is delayed. You know, all callout(9) events are serialized in one
> thread - "swi4: clock".
>
>   So I made a patch that moves all periodic pf(4) job into separate
> context. The patch uses new taskqueue API made by Scott. I have
> ported the API to RELENG_6 and made my patch for RELENG_6. I've
> been running the patch for 27 days and the spurious preemtions
> of CARP backup had gone away. No problems were noticed. The box
> is running SMP kernel on a single CPU box with HTT (2 logical
> CPUs), HTT enabled.
>
>   The patch attached.

Makes sense to me.  I recall that we talked about this problem before and I 
think I even sent you a patch to expire only a fixed amount of states at 
once.  Can't find that patch now, do you remember?  OpenBSD has by now done 
something along those lines and I will import it as soon as 3.9 is ready and 
I have some time.  Could you change the purge part to a kernel thread like 
done in OpenBSD:

http://www.openbsd.org/cgi-bin/cvsweb/src/sys/net/pf.c#rev1.498

I'm not sure which is better, but staying close to the OpenBSD sollution would 
certainly make my life easier.

Thanks for coming up with this!

-- 
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