The following reply was made to PR kern/34639; it has been noted by GNATS.
From: Vladimir Ivanov <wawa@yandex-team.ru>
To: Bill Fumerola <billf@mu.org>
Cc: FreeBSD-gnats-submit@freebsd.org
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, wawa@yandex-team.ru wrote:
>
>
>>>Description:
>>>
>>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.
Best regards,
--
Vladimir Ivanov
Network Operation Center
OOO "Yandex"
e-mail: noc@yandex.net (corporate)
wawa@yandex-team.ru (personal)
www: www.yandex.ru
tel: +7 095 974-3555
fax: +7 095 974-3565
--
A diplomat is someone who can tell you to go to hell in such a way that
you will look forward to the trip.
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