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Date:      Tue, 04 Jan 2005 09:46:19 -0800
From:      Charlie Schluting <charlie@schluting.com>
To:        freebsd-questions@freebsd.org
Subject:   Re: TCPDUMP performance
Message-ID:  <41DAD66B.7080505@schluting.com>
In-Reply-To: <41DAD26C.9010500@sbcglobal.net>
References:  <20050102152416.65565.qmail@web51904.mail.yahoo.com> <41DAD26C.9010500@sbcglobal.net>

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> James Kilton wrote:
> 
>> Hello,
>>
>> We've installed some FreeBSD machines as Gigabit sniffers, and I'm
>> wondering if there are any things I can tweak (e.g., buffer size) to help
>> TCPDUMP capture better (we often see packets dropped by the kernel).
>>
>> Any advice would be appreciated.
>>

This:

sysctl debug.bpf_bufsize=8388608
sysctl debug.bpf_maxbufsize=8388608

As a general rule, you need a decent Pentium 4 to capture > 20K packets/sec 
without drops.

-Charlie



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