[Codel] How to make a bufferbloat fairqueue with tc qdisc

[Codel] How to make a bufferbloat fairqueue with tc qdisc

[Dong Mo]

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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?

Thanks

-Mo Dong

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Re: [Codel] How to make a bufferbloat fairqueue with tc qdisc

[Anirudh Sivaraman]

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
>
> _______________________________________________
> Codel mailing list
> Codel@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/codel
>

Re: [Codel] How to make a bufferbloat fairqueue with tc qdisc

[Dong Mo]

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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
> >
> > _______________________________________________
> > Codel mailing list
> > Codel@lists.bufferbloat.net
> > https://lists.bufferbloat.net/listinfo/codel
> >
>

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