Feedback Linux Scheduling and a Simulation Tool for Wireless Control

Sammanfattning: Computing systems are becoming more and more complex and powerful. It is nowadays not uncommon to run several server applications on the same physical platform. This gives rise to a need for resource reservation techniques, so that administrators may prioritize some tasks, or customers, over others. This thesis gives an introduction to the Linux kernel 2.6 task scheduler, and scheduling related operating system concepts such as priority, nice value, interactivity and task states. The thesis also presents an implementation of a scheduling mechanism, that in a non-intrusive way introduces per task CPU bandwidth reservations in the Linux operating system. The MATLAB/Simulink-based simulator TrueTime is given a short introduction, and the wireless capabilities of the tool are described in more detail. TrueTime is a tool for co-simulation of real-time tasks, network communication, and continuous-time plant dynamics. The modeling of the common medium access control (MAC) layers of IEEE 802.11 and IEEE 802.15.4 is described, along with the radio model used. TrueTime's capabilities to simulate local clocks with drift, Dynamic Voltage Scaling, and battery powered devices are also presented.