层次化动态实时调度框架的设计与实现

摘要

The development of embedded systems is facing new trends including variousness of usage scenarios, strict requirement for real-time feature, complexity of upper applications and assurance of strong robustness, demanding the advance of system safety by means of promoting embedded operating systems. Temporal isolation mechanism is an important part to improve the safety of system, proposing a hierarchical dynamic real-time scheduling framework to be the implementation of temporal isolation. This paper uses the homogeneity of task to generate task sets, which can be the basis of hierarchical framework for task partitioning;testifies the schedulable condition of the framework, designs the structure of scheduling algorithm and realizes the dynamic switching of scheduling algorithm. The simulation result and theoretical analysis indicate that the issued framework can improve the safety of system and dynamically adjust to the variation of system load while guaranteeing the stability of time complexity of context switch.%现有嵌入式系统具有应用场景多变、实时性要求严格、上层应用复杂、鲁棒性较强等特点，在嵌入式操作系统层面对系统防危性要求较高。时间隔离机制是提高系统防危性的重要组成部分，为此，提出一种将层次化动态实时调度框架作为时间隔离的实现策略。引入任务同质性的概念进行任务分划，将产生的任务集作为层次框架的基础，证明多层次框架下实时任务的可调度性条件，设计调度算法结构并实现调度算法的动态切换。仿真结果和理论分析表明，该调度框架在保证上下文切换时间复杂度稳定的前提下，可提高系统防危性并动态应对系统负载的变化。