Re: [LARTC] htb overrate with 2.6.16

[Andy Furniss <andy.furniss@dsl.pipex.com>]

Yanko Kaneti wrote:
> 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

Why default 20 - if you don't have 1:20 it would be better to use 
default 0 which is unshaped and is the default - so ommitting default is 
the same - unclassifed traffic goes through unshaped.

> # 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

The giants are the problem - if you specify mtu XXXXX on 1:2 class it 
should work.

Or you could consider setting mtu on nic to 1500 if that is practical 
for you ie. this traffic is headed somewhere that is going to frag it 
down to 1500 anyway.

Andy.
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