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Date:      Sun, 9 Jun 2002 23:09:37 -0700
From:      Luigi Rizzo <rizzo@icir.org>
To:        Robert Watson <rwatson@freebsd.org>
Cc:        ipfw@freebsd.org
Subject:   Re: New ipfw code available
Message-ID:  <20020609230937.A53454@iguana.icir.org>
In-Reply-To: <Pine.NEB.3.96L.1020610005651.89066B-100000@fledge.watson.org>; from rwatson@freebsd.org on Mon, Jun 10, 2002 at 12:57:44AM -0400
References:  <20020608201909.A41807@iguana.icir.org> <Pine.NEB.3.96L.1020610005651.89066B-100000@fledge.watson.org>

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On Mon, Jun 10, 2002 at 12:57:44AM -0400, Robert Watson wrote:
> Sounds very cool indeed.  However, the usual question when hard-coded-ness
> is traded for flexibility is: what's the performance like?  Do you have
> any performance measurements you could tell us about in the before/after
> scenarios?  You mention 'faster' as well as 'flexible', which bodes well
> :-).

i have not run any comparative test yet, that was the point of the
posting, find some good soul who was willing to run the new and old
code and compare performance :)

Anyways in this case (barring stupid bugs in the implementation of
course) it is rather obvious that the new architecture must be
substantially faster -- the fact is, the old ipfw macroinstruction
has to test some 20-25 distinct flags even when there is nothing
to be done, all of which is filtered out by the compiler with the
new approach. Things would be different if the macroinstructions
were executed in hardware, but they were not...

	cheers
	luigi

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