Avoiding natd overhead

[Fabian Keil]

Chris Bowman <chrishome at austin.rr.com> wrote:

>   I see this question come up now and then on the lists, so, I'll share 
> what I've learned about natd and performance!  First, if your running 
> natd on a processor which supports more functions than just a standard 
> 386,  ie a Pentium, Athlon, etc.  Then I've found compiling natd with 
> make flags for that processor, and with O3 optimizations will make your 
> jaw drop in comparison to the default installed version of natd.

I've learned that if you care about NAT overhead you just don't use natd.

I run two jailed Tor nodes on a Intel Celeron 2.40GHz. With PF disabled
and NAT done with natd, natd uses something between 20 and 30% of the
cpu time.

With PF (filtering, NAT, queueing) enabled I don't see a measurable
increase of cpu usage at all.

I haven't tried recompiling natd with customized flags,
but I doubt that it helps enough to overlook the context
switch penalty.

Fabian
-- 
http://www.fabiankeil.de/
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