On Fri, Dec 21, 2012 at 12:51 PM, Alessandro Bolletta <alessandro@mediaspot.net> wrote:

Hi everybody,
Thanks so much for your useful help! I solved my problem by reproducing bottleneck through HTB queues.
I tried some bandwidth rates and i saw that target must be increased if the available bandwidth is <4mbps. 13ms is a good compromise for that situation.
Also, i removed the switch from my testbed.
Codel works amazingly well, congratulations for the job that has been done!
I'll try to make more tests to ensure that it will be suitable for our needs; we are building a new wireless mesh network in Italy based on a totally new architecture and Codel could be a great improvement for queue management on the nodes.

Thanks again for your courtesy!
Alessandro Bolletta

Kathy,

So in this case, there is another packet of buffering *under* the codel queue in the HTB line discipline (which buffers one packet), plus whatever additional buffering of there may be in the device driver (where the mileage varies).

So codel isn't actually dropping the head of the queue, but the second (or further) packet back, in effect. So the control law computation won't be quite right.

- Jim