Re: DHCP oddity

Brian Candler wrote:

On Mon, Dec 26, 2005 at 12:15:14PM -0600, Skylar Thompson wrote:


While doing some network stress-tests from a dual-CPU x86 FreeBSD 5.4 server, I noticed that a "ping -f" drives dhcpd's CPU usage way up. I put dhcpd into debug mode and didn't get any error messages. I then ran dhcpd with strace, and saw loads of these messages when I started the ping flood:

select(8, [?], [?], [?], NULL)          = 1 ()
gettimeofday({...}, NULL)               = 0
recvfrom(4, 0xbfbfe090, 1500, 0, {...}, [?]) = 84
select(8, [?], [?], [?], NULL)          = 1 ()
gettimeofday({...}, NULL)               = 0
recvfrom(4, 0xbfbfe090, 1500, 0, {...}, [?]) = 84

Does anyone know why this would happen?



Were you running tcpdump or similar at the same time, such that the
interface was put into promiscuous mode?

Check using ifconfig that it is not (i.e. there is no PROMISC flag shown)
_______________________________________________



No. Here's the setup of the NIC:

bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
       options=1a<TXCSUM,VLAN_MTU,VLAN_HWTAGGING>
       inet 159.28.234.1 netmask 0xffffff00 broadcast 159.28.234.255
       inet6 fe80::210:18ff:fe11:ea1f%bge0 prefixlen 64 scopeid 0x1
       ether 00:10:18:11:ea:1f
       media: Ethernet autoselect (1000baseTX <full-duplex>)
       status: active

I've also tried this using the on-board 100Mbps fxp adapter, and I get the same results.

--
-- Skylar Thompson (skylar@xxxxxxxxxxxxxx)
-- http://www.cs.earlham.edu/~skylar/

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