[Cake] Cake latency update

[Pete Heist]

> On Feb 9, 2017, at 9:52 PM, Jonathan Morton <chromatix99 at gmail.com> wrote:
> 
>> On 9 Feb, 2017, at 18:36, Pete Heist <peteheist at gmail.com> wrote:
>> 
>> I’m seeing good latency results for Cake at lower MCS levels (graphs below), in case that wasn’t already known.
> 
> Yes - despite its complexity, Cake has always performed well on latency in comparison to other qdiscs.
> 
> I gather this time you’re comparing it against the mac80211 fq_codel, rather than a conventional qdisc stack?

Yes, this is on stock LEDE, and I hope to complete results on Chaos Calmer.

I haven’t always seen Cake’s latency numbers lower compared to fq_codel. If I take these two:

http://www.drhleny.cz/bufferbloat/fq_codel_fd-wifi-both_40mbit/index.html <http://www.drhleny.cz/bufferbloat/fq_codel_fd-wifi-both_40mbit/index.html>

http://www.drhleny.cz/bufferbloat/cake_fd-wifi-both_40mbit/index.html <http://www.drhleny.cz/bufferbloat/cake_fd-wifi-both_40mbit/index.html>

FQ-CoDel did better in this case, but it was running on the AP (OM2P-HS, 520 MHz MIPS 74Kc). When run on higher powered Intel routers it basically tied fq_codel:

http://www.drhleny.cz/bufferbloat/cake_fd-eth-ap_100ms_40mbit/index.html <http://www.drhleny.cz/bufferbloat/cake_fd-eth-ap_100ms_40mbit/index.html>

http://www.drhleny.cz/bufferbloat/fq_codel_fd-eth-ap_target_5ms_interval_100ms_40mbit/index.html <http://www.drhleny.cz/bufferbloat/fq_codel_fd-eth-ap_target_5ms_interval_100ms_40mbit/index.html>

but then as you lower the bitrate, Cake’s performance on the rrul test seems to get better relative to fq_codel:

http://www.drhleny.cz/bufferbloat/mcstmp/mcs_latency.png <http://www.drhleny.cz/bufferbloat/mcstmp/mcs_latency.png>

I look forward to the throughput shifts being solved, where I see results like this:

http://www.drhleny.cz/bufferbloat/cake_hd-eth-ap_100ms_80mbit/index.html <http://www.drhleny.cz/bufferbloat/cake_hd-eth-ap_100ms_80mbit/index.html>

This is the only thing so far that would keep me from recommending it for my ISP to test. Otherwise the results from Cake are promising… :)

Pete

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