Re: [LARTC] HTB statistics

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

m.innocenti@cineca.it wrote:
> Hi,
>     there is something I'm not able to understand about HTB statistics.
> Why the qdisc show show how many packets are overlimits but in the
> classes there are always 0 packets overlimits or dropped?

Overlimits is more a kernel thing then usefull as a traffic control 
figure and tc qdisc -s .. shows the root 1: htb but tc -s class doesn't.

You can see drops with tc -s class - but the default htb queue is too 
long in this test. Add a specific queue to the class 1:10 so you can 
specify length. eg.

tc qdisc add dev eth0 parent 1:10 handle 10: bfifo limit 64k

> 
> I try to expain with a simple example. I create a qdisc htb with only a 
> class and then i do a lot of traffic.
> pc-innocenti:~# tc qdisc add dev eth0 parent root handle 1: htb default 10
> pc-innocenti:~# tc class add dev eth0 parent 1:1 classid 1:10 htb rate
> 1kbit cei l 1kbit quantum 2000
> 
> The qdisc show that there are packets overlimits:
> pc-innocenti:~# tc -s -d qdisc show
> qdisc htb 1: dev eth0 r2q 10 default 10 direct_packets_stat 1145 ver 3.17
>  Sent 339419 bytes 1533 pkts (dropped 0, overlimits 402)
>  backlog 370p
> 
> The class instead always show 0 packet overlimits or dropped.
> pc-innocenti:~# tc -s -d class show dev eth0
> class htb 1:10 root prio 0 quantum 2000 rate 1000bit ceil 1000bit burst
> 1600b/8 mpu 0b overhead 0b cburst 1600b/8 mpu 0b overhead 0b level 0
>  Sent 66307 bytes 480 pkts (dropped 0, overlimits 0)
>  rate 912bit backlog 448p
>  lended: 32 borrowed: 0 giants: 0
>  tokens: -13238252 ctokens: -13238252
> 
> 

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