[Cerowrt-devel] happy 4th!

Mikael Abrahamsson swmike at swm.pp.se
Tue Jul 9 02:04:39 EDT 2013

On Mon, 8 Jul 2013, Toke Høiland-Jørgensen wrote:

> Did a few test runs on my setup. Here are some figures (can't go higher
> than 100mbit with the hardware I have, sorry).

Thanks, much appreciated!

> Note that I haven't done tests at 100mbit on this setup before, so can't
> say whether something weird is going on there. I'm a little bit puzzled
> as to why the flows don't seem to get going at all in one direction for
> the rrul test. I'm guessing it has something to do with TSQ.

For me, it shows that FQ_CODEL indeed affects TCP performance negatively 
for long links, however it looks like the impact is only about 20-30%.

What's stranger is that latency only goes up to around 230ms from its 
200ms "floor" with FIFO, I had expected a bigger increase in buffering 
with FIFO. Have you done any TCP tuning?

Would it be easy for you to do tests with the streams that "loads up the 
link" being 200ms RTT, and the realtime flows only having 30-40ms RTT, 
simulating downloads from a high RTT server and doing interactive things 
to a more local web server.

Mikael Abrahamsson    email: swmike at swm.pp.se

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