LARTC: trace control for netem: kernelspace

Trace Control for Netem: Emulate network properties such as long-dependency and self-similarity of cross-traffic.

The delay, drop, duplication and corruption values are readout in user space and sent to kernel space via procfs.
The kernel determines the time when new values should be sent by the use of SIGSTOP and SIGCONT signals.
In order to have always packet action values ready to apply, there are two buffers that hold these values.
Packet action values can be read from one buffer and the other buffer can be refilled with new values simultaneously.
If a buffer is empty it will be switched to the other buffer and a SIGCONT signal is sent in order to receive new packet action values.

Having applied the delay value to a packet, the packet gets processed by the original netem functions.

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Patch for linux kernel 2.6.16.19: http://tcn.hypert.net/tcnKernel.patch