[Cake] Cake not more CPU efficient than HTB+FQ-CoDel (anymore)?

[Toke Høiland-Jørgensen]

So we've been saying that one of the benefits of Cake is less CPU usage;
but while trying to benchmark this I got results that would seem to
indicate the opposite.

See attached graph + data files. Basically, I setup a shaper on an
Archer C7 with sqm-scripts simplest.qos. Both HTB+FQ-CoDel and Cake
manages to shape at 250 Mbps, where Cake even shows a bit lower latency.
That is good.

However, when I change the configuration to 400 Mbps (more than the
Archer CPU can handle), Cake tops out at ~260 Mbps, while HTB+FQ-CoDel
manages ~305 Mbps and a slightly lower latency. In both cases I see the
characteristic 95% sirq CPU usage in 'top' on the Archer while the test
is running.

So, um, did we cram so many features into Cake that it no longer uses
less CPU? Can anyone confirm these results?

The tests were run on an openwrt nightly image from today, which has the
latest Cake version from the Cobalt branch.


-Toke

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