Abstract:

A static priority scheduling algorithm for periodic priority exchange was proposed to resolve the low-priority task latency problem in real-time multi-task system. In this method, a fixed period of timeslice was defined, and the two independent tasks of different priorities in the multi-task system exchanged their priority levels periodically. Under the precondition that the execution time of the task with higher priority could be guaranteed, the task with lower priority would have more opportunities to perform as soon as possible to shorten its execution delay time. The proposed method can effectively solve the bad real-time performance of low-priority task and improve the whole control capability of real-time multi-task system.

Key words: priority exchange, real-time multi-task control, periodical exchange, static scheduling algorithm, timeslice

摘要：

针对实时多任务调度时低优先级任务的延迟问题，提出了一种优先级周期性互换的静态优先级调度算法。该方法以固定的时间片为周期，对多任务系统中的某两个不同优先级的独立性任务，周期性地互换它们的优先级级别，在保证较高优先级任务的执行时间的前提下，使得较低优先级的任务有机会尽快执行，以缩短其执行过程中的延迟时间。所提方法能有效解决低优先级任务的实时性问题，从而提高实时多任务系统的整体控制性能。

关键词: 优先级互换, 实时多任务控制, 周期性互换, 静态调度算法, 时间片