[LARTC] Priorities

[Geert Premereur Geert.Premereur@inno.com]

<PRE>Hi,

I have been experimenting with linux bandwidth shaping through tc. Basically
everything works fine, but because of the somewhat scarce and scattered
documentation (I looked through the howto and the mailing list archives (and
even in the kernel sources)) I still have some questions, probably like most
of us ;-)

What is the exact effect of setting a priority for a class?
   e.g.   tc class add dev eth1 ... cbq prio 1 ...
    vs.   tc class add dev eth1 ... cbq prio 8 ...
with all other cbq parameters the same, results in having the first class
consistently allocated only 1% more bandwidth. This difference is much less
than what one would expect. It seems related to the prio parameter however,
because it is independent of the order the classes are specified.

So what's up? When are those priorities used? Do I need to set other
parameters or queues/classes as well? I tried to attach  other queues than
the default to the classes (prio for instance), but that didn't help. The
top level queue is a CBQ

Maybe my method of testing is flawed? I use a program 'ttcp' that
continuously sends maximum size TCP packets to a given port.

Thanks,
Geert



</PRE>