关键词: 星载操作系统, 混合实时任务, 准入控制, 可调度性判定

Abstract: With the development of space technology, the transformation of spaceborne operating system from a closed system with a single task type to an open system with mixed sets of tasks increases the difficulty of predictability and uncertainty of system. The existing table-based scheduling strategy is no longer applicable and can’t solve the schedulability analysis problem of mixed sets of tasks in this scenario. At the same time, this method can’t support the dynamic loading of new tasks during system operation, hindering the intelligent and diversified development of onboard operating systems. In response to this issue, this paper, aiming to ensure the real-time requirements and scalability of spacecraft functions, proposes a two-level admission control strategy based on task’s critical level. The real-time characteristics of tasks are described through model establishment, and the maximum interference generated by tasks with higher priority is comprehensively analyzed. Then, schedulability determination methods based on Interference Bound Function and Response Time Analysis are proposed. Experimental results show that compared to the existing algorithm, our method greatly reduces the cost of computing interference from tasks with higher priority; By tracking the runtime information of tasks, both schedulability determination methods improve real-time performance of algorithms and increase processor utilization, hence providing a theoretical basis for solving the admission control problem of aperiodic tasks in spacecraft systems.

Key words: spaceborne operating system, mixed sets of real-time task, admission control, schedulability determination