面向多级中断系统的任务最差响应时间分析

Worst case response time analysis of multi-level interrupt systems

针对航天嵌入式系统中存在多级中断情况下的时间分析问题,提出了中断与任务混合的响应时间计算模型。该模型中断与任务使用统一的优先级定义,将多级中断嵌套的响应时间分析与任务嵌套的响应时间分析相结合,推导出了混合模型下响应时间计算公式。并进一步比较了中断与任务的异同,阐述了公式中关键参数的含义与计算方法。最后利用开源的LEON3平台和Modelsim软件对所述方法进行了仿真验证,结果表明,任务最差响应时间过估小于5%,可以得到准确的分析结果,有较高的工程应用价值。

A computation model integrated with interrupts and tasks was presented for the analysis of worst case response time（WCRT）for an aerospace embedded system with multilevel interrupts.Both interrupts and tasks was used for a unified priority definition in this model,so the timing analysis of nested interrupts can be combined with task response time analysis techniques. The WCRT of both interrupts and tasks was derived in the integrated model.Furthermore,detailed descriptions of key parameters were proposed and the differences between interrupts and tasks were also discussed.The open source LEON3 processor platform and Modelsim software were introduced to simulate and verify the method.The results show that the overestimate of task WCRT is less than 5% which demonstrates the effectiveness of the method and the value for engineering applications.