If you have 2 htb classes with different prio parameters, the class with the lowest prio parameter gets all the remaining bandwidth from the parent (after the other class has received its rate). The class with the lowest parameter will also the class with the lowest latency. However, if this class is overlimited (there is more traffic then the configured rate), the latency can go up.
The highest prio you can give to a htb class is 7. The lowest prio is 0 (this is also the default value). You can change this in the file "include/linux/pkt_sched.h" with the option TC_HTB_NUMPRIO.
stef.coene@docum.org