[Cerowrt-devel] [Codel] happy 4th!

Toke Høiland-Jørgensen toke at toke.dk
Tue Jul 9 09:13:43 EDT 2013

Eric Dumazet <eric.dumazet at gmail.com> writes:

> What do you mean ? This makes little sense to me.

The data from my previous post
shows fq_codel achieving higher aggregate throughput in some cases than
pfifo_fast does.

> I did not received a copy of your setup, so its hard to tell. But
> using netem correctly is tricky.

The setup is this:

Client <--100mbit--> Gateway <--10mbit--> netem box <--10mbit--> Server

The netem box adds 100ms of latency to each of its interfaces (with no
other qdisc applied). Gateway and server both have ethernet speed
negotiation set to 10mbit or 100mbit (respectively for each of the
tests) on the interfaces facing the netem box.

> My current testbed uses the following script, meant to exercise tcp
> flows with random RTT between 49.9 and 50.1 ms, to check how TCP stack
> reacts to reorders (The answer is : pretty badly.)

Doesn't netem have an option to simulate reordering?

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