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To: James Kilton <kilton9@yahoo.com>
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Subject: Re: TCPDUMP performance
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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.
> 
> Thanks,
> James
> 
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Enable device polling.

Add the following options to your kernel config, and then compile and 
install the new kernel:
	options DEVICE_POLLING
	options HZ=1000

After reboot, enable polling mode on with:
	sysctl kern.polling.enable=1