改进的基于抢占阈值调度的任务响应时间分析方法

Improved Response Time Analysis Method for Scheduling Tasks with Preemption Threshold

基于抢占阈值调度的任务响应时间分析方法是一种新型实时系统任务可调度性判定技术。然而已有的研究工作,有时对以前的任务请求检查过少,可能导致对响应时间估计过低。同时对任务响应时间的分析忽略了任务释放抖动和时钟嘀嗒调度对任务响应时间的影响,造成任务错过期限的现象,系统任务可调度性判定存在潜在的不精确因素。针对上述缺点不足,本文提出改进的基于抢占阈值调度的任务响应时间分析方法,在修正已有方法缺陷的同时,考虑任务释放抖动和时钟嘀嗒调度的影响,引入额外的时间需求,使用改进的任务参数计算系统任务时间需求函数。仿真对比结果表明,改进后的方法较单纯固定优先级抢占阈值调度下的任务响应时间分析方法得到更加精确可调度性分析结果。

The response time analysis method for scheduling tasks with preemption threshold is a novel schedulability technology .But for existing work,it sometimes examines too few previous task invocations, resulting in the potential for underestimated response times. At the same time, because the response time analysis ignores the effect of release jitter and tick schedling to the response time of tasks,resulting in the tasks missing deadline and there is potential unexact factor for the system test of schedulability. For the flaws above,presents a improved response time analysis method for scheduling tasks with preemption threshold when correcting the pitfallsot the exist method.Taking into account the effect and time demand of release jitter and tick schedling by using the modified task parameters in the computation of the time-demand function of task.Simulation result shows that the improved method can abtain the more exact analysis result using preemption threshold scheduling.