[Cake] inbound cake or fq_codel shaping fails on cable on netflix reno

Dave Taht dave.taht at gmail.com
Sat Jul 21 13:42:43 EDT 2018

On Sat, Jul 21, 2018 at 10:28 AM Georgios Amanakis <gamanakis at gmail.com> wrote:
> The previous one was with:
> net.ipv4.tcp_congestion_control=cubic
> I retried with:
> net.ipv4.tcp_congestion_control=reno
> Georgios

In the fast test this has no effect on the remote server's tcp, it's
always going to be reno.

Trying to cross-check behavior using our tests...

There isn't a specific reno setting test in flent for tcp_download as
best as I recall, so I was just calling netperf -H wherever -l 60 --
-K reno,reno

then running the flent ping test as previous mentioned.

(flent-fremont.bufferbloat.net and flent-newark both support reno bbr
and cubic, I haven't checked the others)

PS A side note is that we are not fully successfully moving the
inbound bottleneck to cake (at least in the cable case), as we do get
quite a bit of queuing delay even with linux tcp driving the tests.
I'd long written this off as inevitable, due to the bursty cable mac
but I'm grumpy this morning. 0 delay via fq would be better than even
the 15-40ms I'm getting now with linux flows.....

reno bbr cubic


Dave Täht
CEO, TekLibre, LLC
Tel: 1-669-226-2619

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