A SCHEDULING ALGORITHM OF TIME-TRIGGERED PERIOD TASKS FOR DISTRIBUTED EMBEDDED SYSTEM

摘要

Distributed embedded system can well satisfy real-time requirement. Current scheduling algorithms of TT-triggered period task sets mainly concentrate on task graphs with same periods, list tlevel and list blevel are two classical list scheduling algorithms. The two algorithms can be extended to multi-rate system by adding its period to all parameters of each task graph's other copies in a hyper-period. The modified list blevel algorithm can be further improved to get laxity-based algorithm. The new algorithm considers the characteristics of different deadline in a multi-rate system, and uses the laxity of each task as its priority. The algorithm can be fit for task graphs with the following characteristics: 1.different deadline 2.their deadlines may be less than their period 3.different starting time. In addition, the algorithm use task clustering procedure, lessen the communication cost, and help to expand the algorithm to various practical bus systems.