[LARTC] tc limit

["Martin Schiøtz" <malinux@gmail.com>]

Hi 

I have been playing with tc. I'm using htb and sfq. I tried to setup
shaping of every ip address  within a /20.
I found that there must be an upper limit of about 2096 on the number
of rules (classes, qdiscs or filters). I was testing a /20 which gives
4096 classes, qdiscs and filters. I'm using hashkey to optimize
processing of frames.

When executing the script below - it stops when adding rules for "ip
10.0.7.253" with this error:

handle 1:4097
handle 1:4099
handle 1:4101
RTNETLINK answers: File exists
We have an error talking to the kernel
handle 1:4103
RTNETLINK answers: File exists
We have an error talking to the kernel
handle 1:4105
...
...
etc.

Is there a limit with tc or I'm I doing something wrong ?
(I'm using iproute2-2.6.9-041019)

This is the script:
#!/bin/sh

/sbin/tc qdisc add dev eth1 root handle 1: htb
/sbin/tc class add dev eth1 parent 1: classid 1:3 htb rate 34mbit ceil
34mbit burst 0kbit cburst 0kbit
/sbin/tc filter add dev eth1 parent 1:3 protocol ip u32
/sbin/tc filter add dev eth1 parent 1:3 handle 3: protocol ip u32 divisor 256
/sbin/tc filter add dev eth1 protocol ip parent 1: u32 match ip dst
10.0.0.0/20 hashkey mask 0x000000ff at 16 link 3:

echo handle 1:13
/sbin/tc class add dev eth1 parent 1:3 classid 1:13 htb rate 512kbit
ceil 512kbit burst 0k cburst 0k
/sbin/tc qdisc add dev eth1 parent 1:13 handle 13: sfq perturb 4
/sbin/tc filter add dev eth1 protocol ip parent 1:3 u32 ht 3:1: match
ip dst 10.0.0.1 flowid 1:13

echo handle 1:15
/sbin/tc class add dev eth1 parent 1:3 classid 1:15 htb rate 512kbit
ceil 512kbit burst 0k cburst 0k
/sbin/tc qdisc add dev eth1 parent 1:15 handle 15: sfq perturb 4
/sbin/tc filter add dev eth1 protocol ip parent 1:3 u32 ht 3:2: match
ip dst 10.0.0.2 flowid 1:15
...
...
echo handle 1:4101
/sbin/tc class add dev eth1 parent 1:3 classid 1:4101 htb rate 512kbit
ceil 512kbit burst 0k cburst 0k
/sbin/tc qdisc add dev eth1 parent 1:4101 handle 4101: sfq perturb 4
/sbin/tc filter add dev eth1 protocol ip parent 1:3 u32 ht 3:fd: match
ip dst 10.0.7.253 flowid 1:4101
...
...
echo handle 1:8201
/sbin/tc class add dev eth1 parent 1:3 classid 1:8201 htb rate 512kbit
ceil 512kbit burst 0k cburst 0k
/sbin/tc qdisc add dev eth1 parent 1:8201 handle 8201: sfq perturb 4
/sbin/tc filter add dev eth1 protocol ip parent 1:3 u32 ht 3:ff: match
ip dst 10.0.15.255 flowid 1:8201
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