[Cake] Backporting 'tc class' support

[Toke Høiland-Jørgensen]

Dave Taht <dave.taht at gmail.com> writes:

> I am curious if the new tc class support would allow for recognizing
> sebastian's desire to have the llc (?) dsl control packets moved to
> the higher priority tin?
>
> Similarly, there were other things in early-sqm (like deprioritizing
> ping, prioritizing dns) that I liked, but disliked using iptables to
> use.

You can write a tc filter in BPF, which allows you to do arbitrary
matching on packet data... So as long as the packets go through the
qdisc, the answer would be yes :)

> lastly, the hopelessly overloaded skb->priority field is hopefully
> still not recognized for anything that actually sets skb->priority
> naively?

CAKE will only react to the priority field if the upper 16 bits match
the major number of the qdisc; so anything that sets priority has to
know about the qdisc configuration for it to stick...

-Toke