Re: SFQ on HFSC leaf does not seem to work

[Eric Dumazet <eric.dumazet@gmail.com>]

Le vendredi 23 décembre 2011 à 11:44 -0500, John A. Sullivan III a
écrit :
> On Fri, 2011-12-23 at 17:16 +0100, Eric Dumazet wrote:
> > Le vendredi 23 décembre 2011 à 10:26 -0500, John A. Sullivan III a
> > écrit :
> > 
> > > Yes.  This is a problem I have with netem on ingress traffic.  I use the
> > > filter on ffff: to redirect to ifb0 for the ingress traffic shaping.  I
> > > cannot figure out a way to redirect a second time to ifb1 for the netem
> > > qdisc.  I tried putting two action mirred statements in the filter but
> > > that did not work.  Unlike eth1, I cannot attach a filter further down
> > > the ifb0 hfsc hierarchy because one can't redirect one ifb into another
> > > ifb.  Thus, the only way I could figure out how to do inbound netem was
> > > to replace the terminal qdisc with netem rather than SFQ.  I'd love to
> > > be able to do that differently.  I tried attaching netem to the SFQ but
> > > that failed (I assume because SFQ is classless) and I tried the other
> > > way around, attaching SFQ to netem since you mentioned netem could take
> > > a class but that did not work either.
> > 
> > Unfortunately, netem wants to control skbs itself, in a fifo queue.
> > 
> > To implement what you want, we would need to setup a second qdisc,
> > and when packets are dequeued from internal netem fifo, queue them in
> > second qdisc.
> > 
> > 
> > 
> I thought I tried to do that but I must have done it incorrectly.  I
> would think something like:
> 
> tc qdisc add dev eth1 ingress
> tc filter add dev eth1 parent ffff: protocol ip prio 50 u32 match u32 0 0 action mirred egress redirect dev ifb0
> tc qdisc add  dev ifb0 root handle 4 netem delay 25ms 5ms distribution normal loss 0.1% 30%
> tc qdisc add dev ifb0 parent 4:0 handle 1: hfsc default 20
> 
> but I get:
> root@testswitch01:~# tc qdisc add dev ifb0 parent 4:0 handle 1: hfsc default 20
> RTNETLINK answers: Operation not supported
> 
> What did I do wrong? Thanks - John
> 

Maybe I was not clear :

netem currently uses a fifo queue, you cant change this, without
patching kernel.