The following reply was made to PR kern/34639; it has been noted by GNATS.
From: Vladimir Ivanov <firstname.lastname@example.org>
To: Bill Fumerola <email@example.com>
Subject: Re: kern/34639: IPFW skipto works too slow
Date: Wed, 06 Feb 2002 09:07:34 +0300
Bill Fumerola wrote:
> On Tue, Feb 05, 2002 at 05:53:19PM +0300, firstname.lastname@example.org wrote:
>>The original implementation of skipto rule use brute-force to find the appropriate rule.
>>The suggested implementation use indexed access.
> the ipfw code caches the skipto rule the first time it gets used. i don't
> think cacheing it in a different spot really helps anything.
I've never seen caching of skipto's in the code. Maybe the cacheing is
very tricky. ;-)
> are you actually seeing performance problems? can you actually prove
> that ipfw is faster with this change?
Sure, I've tested it on a real system. The system was unable to process more than several hundred rules with
skipto's. It was losing packets. 'top' utility reported about 99% CPU for 'interrupts' and the
total bandwidth degradated twice after adding even only skipto rule in the tail of chain. The behaviour after
applying patch is expected.
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