System level design techniques for real-time embedded systems.

摘要

The increasing complexity of real-time embedded systems and stringent time-to-market demands have put more and more pressure on designers. Computer-aided design of such systems at system level has shown to be a promising methodology to mitigate this problem. This dissertation focuses on two important issues in the system-level design: partitioning, and scheduling. The contributions of the dissertation include: (i) A new partitioning methodology which incorporates hierarchical structures for both system functionalities and hardware modules, and can efficiently make trade-offs between the quality of the solutions and the computational cost. An efficient technique is also proposed for evaluating the quality of alternative designs based on the user's preference. (ii) An improved technique, based on utilization bound calculation, is introduced to rapidly check the schedulability of a large number of design alternatives during design exploration. This technique is further extended to take into account communications and precedence constraints among tasks. (iii) An energy efficient heuristic approach for scheduling fixed-priority real-time systems on a variable speed processor, which also produces the minimum constant voltage needed to feasibly schedule the real time systems. To further study the inherent theoretical limitation in terms of energy saving for a variable speed processor executing a fixed-priority real-time system, an optimal approach is also proposed. With the guidance of the optimal schedule, our heuristic approach is shown to be both effective and efficient in saving power/energy compared with other existing approaches. (iv) New techniques and methodologies for scheduling fixed-priority real-time systems with (m, k) constraints, a Quality of Service constraint requiring that at least m out of any k consecutive instances of a certain task must meet their deadlines.; The problems discussed in the dissertation are rather general in real-time embedded system designs, and these methodologies and techniques are important both in theoretical and practical sense.