high cpu usage on natd / dhcpd

[Eggert, Lars]

Hi,

> I have a small system running FreeBSD 8.2 that does NAT using ipfw and 
> natd to systems attached to two interfaces: em0 and wlan0.  I have a 
> dhcpd daemon issuing leases on those interfaces.  The system has an em1 
> interface plugged into a cable modem where it obtains a DHCP lease from 
> an ISP.
> 
> For some reason, when traffic from the Internet terminates on the system 
> itself (I scp a file from the computer) the natd and dhcpd processes 
> consume significant CPU, and the throughput is less than I expect. 
> Traffic that passes through to a computer behind the NAT flows without 
> causing the natd or dhcpd processes to measurably consume CPU.

I see exactly the same issue on -STABLE. Have you been able to figure out the cause?

Thanks,
Lars