[LARTC] htb overrate with 2.6.16

[Yanko Kaneti <yaneti@declera.com>]

Hi

Here is something that worked with with 2.6.10-1.771_FC2smp and stopped
working when I upgraded to 2.6.16-1.2069_FC4smp.
These are fedora kernels and the network controller is an Intel Gbit
(e1000) running a 100 Mbps Full Duplex.
Don't know how or if this matters but the 2.6.10 kernel has
CONFIG_X86_HZ\x1000 and the 2.6.16 has CONFIG_HZ%0

The idea is to just shape to , say 2Mbit, a certain kind of traffic
everything else should goes unshaped.

# tc qdisc add dev eth0 root handle 1: htb default 20
# tc class add dev eth0 parent 1: classid 1:2 htb rate 2Mbit
# tc qdisc add dev eth0 parent 1:2 sfq perturb 10
# tc filter add dev eth0 protocol ip parent 1:0 prio 1 handle 50 fw flowid 1:2

This was working as expected with 2.6.10
I've tried creating a proper 1:1 100Mbit parent to be the default but it
didn't help. And it was working fine without it on 2.6.10

With the 2.6.16 kernel I get results like

# tc -s -d class show dev eth0
class htb 1:2 root leaf 800b: prio 0 quantum 25000 rate 2000Kbit ceil 2000Kbit burst 2600b/8 mpu 0b overhead 0b cburst 2600b/8 mpu 0b overhead 0b level 0
 Sent 189796883 bytes 20626 pkt (dropped 0, overlimits 0 requeues 0)
 rate 3484Kbit 45pps backlog 0b 0p requeues 0
 lended: 20627 borrowed: 0 giants: 30926
 tokens: -9768 ctokens: -9768

As you can see the correctly calculated rate is way above the ceiling
and I've seen it go as fast as this certain type of traffic can go
(something like 8-10Mbits), i.e. the class doesn't seem to shape at all.
No drops or overlimits.

FWIW the cbq in 2.6.10 kernel was working fine as well until the
controller changed from a 100Mbit it a Gbit one and thats why I switched
to htb. The cbq in 2.6.16 is still similarly broken (in a different than
htb way)


Thanks in advance for any insight on this.
Yanko

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