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Date:      Thu, 24 Jul 2003 15:57:48 -0700
From:      Luigi Rizzo <rizzo@icir.org>
To:        "Eric W. Bates" <ericx@vineyard.net>
Cc:        freebsd-net@freebsd.org
Subject:   Re: Profiling ipfw2 performance
Message-ID:  <20030724155748.B35706@xorpc.icir.org>
In-Reply-To: <002501c3522f$67e4e320$68c311cc@fortiva>; from ericx@vineyard.net on Thu, Jul 24, 2003 at 06:03:25PM -0400
References:  <002501c3522f$67e4e320$68c311cc@fortiva>

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On Thu, Jul 24, 2003 at 06:03:25PM -0400, Eric W. Bates wrote:
> Can someone please point me to a method for measuring the packet lag between interfaces when using ipfw and/or ipfw2?

in RELENG_4, i386 kernels you can add the option

	options	KERN_TIMESTAMP

which then allows you to use the TSTMP() macros (defined and
documented in /sys/i386/include/param.h) to record timestamps
using the TSC register, and export the readings to userland
using a sysctl.
This way you can get some reasonable numbers in a non-intrusive way.

	cheers
	luigi

> Thanks.
> 
> Eric W. Bates
> ericx@vineyard.net
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