Thanks. I made a wrong observation for the last email that I used ping to
measure the latency of TCP and was expecting to see a latency explode.

So do you know a way to measure the running TCP's packet latency
experienced at the qdisc?
Thanks a lot
-Mo




2013/12/5 Anirudh Sivaraman <sk.anirudh@gmail.com>

> On Thu, Dec 5, 2013 at 2:52 PM, Dong Mo <montedong@gmail.com> wrote:
> > Dear List,
> > I am trying to make a bufferbloat fairqueue with qdisc and compare that
> with
> > fq_codel.
> > However, I am now having some hard time doing it.
> >
> > The commands I am using are:
> >
> > tc qdisc add dev $IFACE root handle 1: htb default 1
> > tc class add dev $IFACE parent 1: classid 1:1 htb rate 40mbit
> > tc qdisc del dev eth4 parent 1:1 handle 10: sfq perturb 10
> >
> > And sending packet from the sender, where sfq qdisc is set, to the
> receiver,
> > the queuing delay is quite small and is approximately the same as when
> > fq_codel enabled.
> >
> > However, if I am not using sfq (only htb set), and send only one flow
> over
> > this link, the delay will explode again.
> >
> > So is sfq here cut off the queue length somehow? How should I make a
> > bufferbloat fair queue on linux box using tc qdisc?
> >
>
> You could start with the fq_codel qdisc and set the codel interval and
> target parameters to absurdly large values (say 1000 seconds each) to
> simulate a qdisc that has fair queuing but almost never drops a
> packet.
>
> Anirudh
>
> > Thanks
> >
> > -Mo Dong
> >
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> >
>