RELENG_8 flowtable issue ?

[Mike Tancsa]

I noticed on a recent RELENG_8 box, the CPU became pegged.  Looking 
at top, it has something to do with flowtables

last pid: 49269;  load 
averages:  2.76,  2.29,  2.07 
               up 18+09:36:04  21:42:07
89 processes:  6 running, 70 sleeping, 13 waiting
CPU:  0.0% user,  0.0% nice, 50.0% system,  0.0% interrupt, 50.0% idle
Mem: 52M Active, 1496M Inact, 172M Wired, 16K Cache, 112M Buf, 280M Free
Swap: 3072M Total, 3072M Free

   PID USERNAME   THR PRI NICE   SIZE    RES STATE   C   TIME   WCPU COMMAND
    10 root         2 171 ki31     0K    16K RUN     0 809.5H 100.00% idle
    18 root         1  44    -     0K     8K CPU0    0 117:30 100.00% 
flowcleaner

as the flowcleaner is running full speed.  Does anyone know what that 
might be about ?

sysctl -a |grep flow
kern.sigqueue.overflow: 0
net.inet.ip.output_flowtable_size: 32768
net.inet.tcp.reass.overflows: 0
net.inet.flowtable.stats:
net.inet.flowtable.nmbflows: 50176
net.inet.flowtable.tcp_expire: 86400
net.inet.flowtable.fin_wait_expire: 600
net.inet.flowtable.udp_expire: 300
net.inet.flowtable.syn_expire: 300
net.inet.flowtable.enable: 0
net.inet.flowtable.debug: 0
net.inet6.ip6.auto_flowlabel: 1
# sysctl -a net.inet.flowtable.stats
net.inet.flowtable.stats:
table name: ipv4
         collisions: 958
         allocated: 0
         misses: 992897
         max_depth: 1
         free_checks: 36419211
         frees: 785503
         hits: 9745703272
         lookups: 9746696168

The box runs mpd5 to terminate some l2tp connections and runs ospf 
and has just one area. In its releng7 incarnation, all was quite solid.

I am going to disable flowtables on this box for now, but if I see it 
happen on another, what can I do to better debug it ?

         ---Mike


--------------------------------------------------------------------
Mike Tancsa,                                      tel +1 519 651 3400
Sentex Communications,                            mike at sentex.net
Providing Internet since 1994                    www.sentex.net
Cambridge, Ontario Canada                         www.sentex.net/mike