1553B总线上消息的实时调度

Real time scheduling of messages on 1553B bus

为了优化1553B总线传输性能,降低总线上消息传输的延迟时间,讨论了周期消息和非周期消息混合传输情况下总线上的消息调度策略。首先,借鉴周期任务的调度模型对周期消息进行建模,提出了改进的速率单调消息调度算法。然后,利用排队论建立非周期消息的M/M/1排队模型,定量分析了1553B总线的平均响应时间和总线利用率等时间性能参数,并对非周期消息的延迟时间进行优化,推导出总线最优服务率和最小平均延迟时间的计算公式,给出了非周期消息的调度算法。最后,对上述算法在消息混合传输下的可调度性进行了验证。实验结果表明,在总线利用率达96%时,混合消息的平均响应时间为0.713ms。在消息混合传输的情况下,非周期消息的平均响应时间和M/M/1排队模型下理想的非周期响应时间偏差不超过10%。上述算法时间响应特性良好,能够保证周期消息和非周期消息的实时调度。

In order to optimize the transmission performance of 1553B bus and to reduce the transmission delay time of messages on the bus, a scheduling strategy for the mixed periodic and aperiodic messages on the bus was proposed. Firstly, a model for the periodic messages was established according to the scheduling model of periodic tasks, and an improved rate-monotonic scheduling algorithm was presented. Then, the M/M/1 queuing model for aperiodic messages was established based on the queue, theory, and the time performance parameters of the 1553B bus were quantitatively analyzed, including average response time, bus utilization, and so on. Furthermore, the delay time for aperiodic messages was optimized. The formulas for optimal bus service rate and minimal average delay time were derived; and the scheduling algorithm of aperiodic messages was presented. Finally, the scheduling characteristic of the mixed messages for above algorithm was validated. The experimental results indicate that the average response time of the mixed messages is only 0. 713 ms when the utilization of155313 bus is up to 96%. The deviation of the average response time between aperiodic messages and M/M/1 queuing model is less than 10 % under the condition of transmitting mixed messages. Obtained results show that the algorithm has good response characteristics, and can ensure the real-time scheduling of the periodic and aperiodic messages on the 1553B bus.