Bandwidth shaping with CBQ

Hiya
I am trying to setup some bandwidth shaping using the kernel CBQ modules.
I am using the cbq.init script to configure tc for me.

All seems well until I try to implement larger rates. I have a box with
3 interfaces, two of which are setup as a bridge, the third connects
directly to this bridge. The CBQ tree is applied to the ports on the
bridge.

Now these ports are set to 100Mbs, and I am trying to rate limit to
60Mbps per network, so that no more than 60Mbps can be recieved from any
of the given subnets. When I apply the rule the data flow is limited to
30Mbps (approx) regardless of the rate I specify, unless I specify one the
same as the interface, in which case a full 100Mbps is transmitted.

I have adjusted the avpkt to be 1500 (initially it was 1000 and the
throughput was 10Mbps).

The box itself has plenty of umph (dual 2.6 GHz Xeon 2GB RAM) so I can't
see that being a problem, and CPU never goes about 1%

Is there some kind of internal limit with CBQ QoS stuff?

any help resolving this much appreciated

Graeme

On Fri, 14 May 2004 17:51:57 +0100, Graeme Hinchliffe wrote:

> Hiya
> I am trying to setup some bandwidth shaping using the kernel CBQ modules.
> I am using the cbq.init script to configure tc for me.
>
> All seems well until I try to implement larger rates. I have a box with
> 3 interfaces, two of which are setup as a bridge, the third connects
> directly to this bridge. The CBQ tree is applied to the ports on the
> bridge.
>
> Now these ports are set to 100Mbs, and I am trying to rate limit to
> 60Mbps per network, so that no more than 60Mbps can be recieved from any
> of the given subnets. When I apply the rule the data flow is limited to
> 30Mbps (approx) regardless of the rate I specify, unless I specify one the
> same as the interface, in which case a full 100Mbps is transmitted.
>
> I have adjusted the avpkt to be 1500 (initially it was 1000 and the
> throughput was 10Mbps).
>
> The box itself has plenty of umph (dual 2.6 GHz Xeon 2GB RAM) so I can't
> see that being a problem, and CPU never goes about 1%
>
> Is there some kind of internal limit with CBQ QoS stuff?
>
> any help resolving this much appreciated
>
> Graeme


There is no "internal limit" in cbq.

tc -s class show dev eth0
tc -s class show dev eth1
tc -s class show dev eth2

will show you some statistics. You can then identify which class is doing
the transmitting, and see where the problem is.