From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Tue, 28 Jul 2009 16:44:51 +0800

Well the fact that as it stands the only true multiqueue qdisc
is the default is a mere coincidence.  There is no fundamental
reason why non-default qdiscs cannot be made multiqueue aware,
well, for some of them anyway.

For example, sfq can naturally be enhanced as a multiqueue qdisc
just like the default qdisc.

So I don't think we want to prejudice what a future non-default
qdisc may support.

The idea is that it cannot be done anywhere we currently
limits, decisions, etc. are all done with "device" scope.

And I think SFQ even falls into that category.

You would need a special SFQ that makes sure to break down traffic
identically to how the TX queue selection divides traffic, and even
then I'm not even so sure how implementable that is.