Cake FAQ

Cake is the comprehensive queue management system the bufferbloat project has been working on since 2013. It is the rollup of 3 years of deployment experience using the htb + fq_codel based sqm-scripts and is included in the Linux kernel since v4.19.

What was the origin of the name?

Initially it came from the movie 2010 where an American was trying to explain the idioms “Easy as pie”, and “Piece of cake” to a Russian, who kept getting it wrong. Where it started was when Dave Taht tried to explain the need for a comprehensive queue management system to an audience in the ietf aqm working group, and was basically booed off the stage.

Later on it became a reference to the game “portal” - where, at the conclusion of the game, the AI promises that: “everyone will have cake”.

It is also (in a grand tradition of RED vs Blue) a backhanded reference to “Pie”, which is a competing AQM algorithm missing many of the features of cake.

The backronym invented for it became “Common Applications Kept Enhanced” - which is also, actually, exactly what it does.

Despite our affection for the name there is still time to change it to something else - googling for “cake shaper” does not result in anything useful. CQM, SQM would seem to have more useful google-fu, but…

enabling cake

Changing to the cake qdisc:

tc qdisc replace dev eth0 root cake ethernet bandwidth 1gbit

Any unmentioned parameter will be set to a sane default. It assumes you have cake available in your kernel.

Changing settings in real time:

tc qdisc change dev eth0 handle 1: cake bandwidth 1Mbit

This does not cause packet loss.