Abstract:

To improve the safety of real-time system at transient overload, a schedule algorithm based on mixed priority is proposed. The priority of the algorithm consists of relative deadline priority and relative slack priority. With relative slack, whether tasks will miss deadline can be predicted. Through the complete CPU preemption, frequent context switch can be avoided. Simulation results show that the presented algorithm improves the efficiency of task schedule and effectively decreases the Missed Deadline Percentage(MDP) at transient overload.

Key words: real-time system, safety schedule, schedule algorithm, task priority, Missed Deadline Percentage(MDP)

摘要：

为增强实时系统任务过载时的防危性，提出一种混合优先级的防危调度算法，其优先级由相对截止期优先级和相对松弛度优先级组成，通过相对松弛度预测任务的可完成性，并采用完全抢占方式防止处理器资源的竞争抖动。仿真结果表明，该算法可充分利用处理器资源，能在发生瞬时过载时有效降低任务的截止期错失率。

关键词: 实时系统, 防危调度, 调度算法, 任务优先级, 截止期错失率

CLC Number: 

• TP391