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Date:      Fri, 7 Aug 1998 17:29:30 +0200 (MET DST)
From:      Luigi Rizzo <luigi@labinfo.iet.unipi.it>
To:        net@FreeBSD.ORG
Subject:   optimizing ipfw...
Message-ID:  <199808071529.RAA15460@labinfo.iet.unipi.it>

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Hi,

i was looking at if there is a need to optimize ipfw code, and tried to
instrument the code a little bit.

It turns out that on a P90, starting from the main loop to the exit
point:

	for (; chain; chain = chain->chain.le_next) {
		...
	}

the code takes about 7us on a one-rule (accept) database
(including two calls to microtime).

Adding 3 not-matching rules (matching src/dst/interface, failing on port
number) to the database before the matching one, brings the
check time to about 16us per pass, or 3us per rule.

Just a data point i guess... i am not so sure on what to optimize,
suggestions ?
	
	luigi
-----------------------------+--------------------------------------
Luigi Rizzo                  |  Dip. di Ingegneria dell'Informazione
email: luigi@iet.unipi.it    |  Universita' di Pisa
tel: +39-50-568533           |  via Diotisalvi 2, 56126 PISA (Italy)
fax: +39-50-568522           |  http://www.iet.unipi.it/~luigi/
_____________________________|______________________________________




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