EPTS:一种实时动态电压调整的抢占阈值调度器

低功耗目前已成为嵌入式实时系统设计中非常重要的性能需求。动态电压调度DVS机制通过动态调整处理器电压进而有效降低系统功耗,正在逐渐得到广泛应用。抢占阈值调度策略实现双优先级系统,每个任务具有两个优先级,任务优先级被用于任务之间竞争处理器,而抢占阈值作为任务开始运行后实际使用的优先级,从而减少现场切换次数,降低系统功耗,同时也提高整个任务集合的可调度性。本文提出一种在线节能调度算法EPTS,拓展抢占阈值调度模型,在任务执行过程中动态调节处理器电压,力求在保证任务集合可调度性的前提下尽可能减少系统功耗,提高系统性能。而后在AMDAthlon4处理器和RT-Linux平台上实现了EPTS调度器,实验证明对于实际任务集合能够有效节能,提高了处理器的利用率,改善了RT-Linux的实时性能。

EPTS:A Dynamic Voltage Scaling Real-Time Scheduler on Fix-Priority Tasks with Preemption Thresholds

Low-power consumption has become a very important performance requirement in embedded real-time systems.The DVS techniques can reduce power consumption efficiently by dynamically scaling the processor voltage,and have been being increasingly used.The preemption threshold scheduling(PTS) policy is a dual-priority task scheduling mechanism,in which priority is used to obtain the processor,and preemption threshold is used as the actual priority when a task is scheduled to run,which leads to reducing the number of unnecessary preemptions,improving the schedulability of the task set.In this paper,an online energy-efficient scheduler on fixed-priority tasks with preemption thresholds is proposed,which tries to balance energy consumption against real-time responses as much as possible.Then,this approach is validated using the RT-Linux testbed on the AMD Athlon 4 processor.The results show that DVS leads to in significant energy savings for practical real-life task sets.