Netdata reads /proc//stat for all processes, once per second and extracts utime and stime (user and system cpu utilization), much like all the console tools do. But it also extracts cutime and cstime that account the user and system time of the exit children of each process. By keeping a map in memory of the whole process tree, it is capable of assigning the right time to every process, taking into account all its exited children.

Netdata monitors tc QoS classes for all interfaces. If you also use FireQOS it will collect interface and class names. There is a shell helper for this (all parsing is done by the plugin in C code - this shell script is just a configuration for the command to run to get tc output). The source of the tc plugin is here. It is somewhat complex, because a state machine was needed to keep track of all the tc classes, including the pseudo classes tc dynamically creates. You can see a live demo here.