ipfw rule processing performances

[Luigi Rizzo]

On Thu, Oct 27, 2011 at 02:53:30PM +1100, Ian Smith wrote:
> On Wed, 26 Oct 2011, Julian Elischer wrote:
>  > On 10/26/11 2:39 PM, Michael Sierchio wrote:
>  > > On Wed, Oct 26, 2011 at 11:39 AM, Julian Elischer<julian at freebsd.org>
>  > > wrote:
>  > > 
>  > > > read up on all the things you can do with tablearg.. sometimes a single
>  > > > table can replace dozens of rules.
>  > > Julian - would you be so kind as to give an example?
>  > > 
>  > > - M
>  > > 
>  > off the top of my head:
>  > 
>  > implement an ad-hoc RErouting table using   fwd  tablearg
>  > implement entirely differnt rules for a complicated set of subnets using
>  > skipto tablearg
> 
> But in this context, isn't skipto tablearg time-expensive, in that it 
> can't use the cached target of a normal skipto, but must to walk the 
> ruleset from the skipto to the resulting rule each time?

Since late 2009 it does a binary search on the rules so it is log(N) in the
number of rules, not so slow.

cheers
luigi