SFQ flow classifier, works for imq0, not for eth1

[Ben Pfountz <netprince@vt.edu>]

Hey Everyone,

Any direction with this problem would be greatly appreciated.  For some 
reason when I add a SFQ flow classifier using tc filter, the sfq qdisc 
stops forwarding packets.  (strangely though, a few packets are 
forwarded before things stop working)

I am working with an openwrt based router, trying to add SFQ flow 
classifier support to openwrt's qos-scripts.  I have simplified the TC 
commands down to these to try to find the problem.

tc qdisc add dev eth1 root handle 1: htb default 7
tc class add dev eth1 parent 1: classid 1:7 htb rate 500mbit ceil 
1000mbit prio 3
tc qdisc add dev eth1 parent 1:7 handle 10: sfq perturb 10
tc filter add dev eth1 protocol ip parent 10: handle 2 flow hash keys 
src,dst divisor 1024



Without the last line, packets flow normally as shown by

# tc -s -d qdisc show dev eth1
qdisc htb 1: root refcnt 2 r2q 10 default 7 direct_packets_stat 0 ver 3.17
  Sent 856 bytes 11 pkt (dropped 0, overlimits 0 requeues 0)
  rate 0bit 0pps backlog 0b 0p requeues 0
qdisc sfq 10: parent 1:7 limit 127p quantum 1514b flows 127/1024 perturb 
10sec
  Sent 856 bytes 11 pkt (dropped 0, overlimits 0 requeues 0)
  rate 0bit 0pps backlog 0b 0p requeues 0


With the last line, I see this

tc -s -d qdisc show dev eth1
qdisc htb 1: root refcnt 2 r2q 10 default 7 direct_packets_stat 0 ver 3.17
  Sent 5019 bytes 53 pkt (dropped 40, overlimits 0 requeues 0)
  rate 0bit 0pps backlog 0b 0p requeues 0
qdisc sfq 10: parent 1:7 limit 127p quantum 1514b flows 127/1024 perturb 
10sec
  Sent 5019 bytes 53 pkt (dropped 40, overlimits 0 requeues 0)
  rate 0bit 0pps backlog 0b 0p requeues 0


I have tried every combination of hash keys and divisor I can think of, 
but the problem remains.

The system is linux 2.6.32.25, iproute 2.6.35, and cls_flow is loaded.

Does anyone have any suggestions?

What is the TC command to view the SFQ internal queues as described here?
http://www.mail-archive.com/netdev@vger.kernel.org/msg60637.html

Thanks!

Ben