Re: re(4) 100% interrupt load

[Ian McIntosh <ianm%cat.co.za@localhost>]

On 2009/12/11 02:58 PM, Steven Bellovin wrote:
> One obvious item is that tcpdump normally puts the NIC into promiscuous mode.  
> What happens if you use 'tcpdump -p' instead?  Also, what does 'ifconfig' tell 
> you about the interface before and after running tcpdump (without -p)?

I tried:

tcpdump -p -i re1

but it shows no traffic.


Results as follows:

ifconfig -a before 'tcpdump -i re1':

re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        
capabilities=3f80<TSO4,IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx,TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx>
        enabled=0
        address: 00:01:29:21:74:6d
        media: Ethernet autoselect (1000baseT full-duplex)
        status: active
        inet 10.2.8.103 netmask 0xffff0000 broadcast 10.2.255.255
        inet6 fe80::201:29ff:fe21:746d%re0 prefixlen 64 scopeid 0x1
re1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        
capabilities=3f80<TSO4,IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx,TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx>
        enabled=0
        address: 00:01:29:21:74:6c
        media: Ethernet autoselect (1000baseT full-duplex)
        status: active
        inet 10.216.124.131 netmask 0xffffffe0 broadcast 10.216.124.159
        inet6 fe80::201:29ff:fe21:746c%re1 prefixlen 64 scopeid 0x2
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33192
        inet 127.0.0.1 netmask 0xff000000
        inet6 ::1 prefixlen 128
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3


top before 'tcpdump -i re1':

load averages:  0.00,  0.07,  0.10 up 0 days, 14:45   07:16:00
72 processes:  71 sleeping, 1 on processor
CPU0 states:  0.0% user,  0.0% nice,  0.0% system, 97.0% interrupt,  
3.0% idle
CPU1 states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  
100% idle
Memory: 206M Act, 4440K Wired, 43M Exec, 52M File, 187M Free
Swap: 1000M Total, 1000M Free


ifconfig -a after 'tcpdump -i re1':

re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        
capabilities=3f80<TSO4,IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx,TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx>
        enabled=0
        address: 00:01:29:21:74:6d
        media: Ethernet autoselect (1000baseT full-duplex)
        status: active
        inet 10.2.8.103 netmask 0xffff0000 broadcast 10.2.255.255
        inet6 fe80::201:29ff:fe21:746d%re0 prefixlen 64 scopeid 0x1
re1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        
capabilities=3f80<TSO4,IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx,TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx>
        enabled=0
        address: 00:01:29:21:74:6c
        media: Ethernet autoselect (1000baseT full-duplex)
        status: active
        inet 10.216.124.131 netmask 0xffffffe0 broadcast 10.216.124.159
        inet6 fe80::201:29ff:fe21:746c%re1 prefixlen 64 scopeid 0x2
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33192
        inet 127.0.0.1 netmask 0xff000000
        inet6 ::1 prefixlen 128
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3


top after 'tcpdump -i re1':

load averages:  0.85,  0.40,  0.22 up 0 days, 14:50   07:20:59
72 processes:  70 sleeping, 2 on processor
CPU0 states: 33.8% user,  0.0% nice, 21.9% system,  8.0% interrupt, 
36.3% idle
CPU1 states:  2.0% user,  0.0% nice,  1.0% system,  0.0% interrupt, 
97.0% idle
Memory: 210M Act, 4440K Wired, 43M Exec, 53M File, 183M Free
Swap: 1000M Total, 1000M Free