基于时间帧的处理器PFair调度改进算法

为了解决PFair算法进行交互任务调度时,由于忽略了不同阶段的周期性任务而导致多个线程之间任务的迁移问题以及空间和时间的浪费问题,提出了基于时间帧的处理器PFair调度改进算法。该算法基于周期性任务系统的特点,引入时间帧控制和改变本地周期性任务调度来限制任务迁移,从而实现对PFair算法的改进。为了评估算法的迁移开销和公平性,通过实验对普通PFair算法及本文所提出的改进算法ERfair进行对比实验,结果表明,改进算法ERfair能够通过时间帧内调度和分区控制大大降低任务在不同处理器间的迁移次数。基于时间帧的处理器PFair调度改进算法在保证公平性的同时,提高了系统的效率,应用于多核处理器上的任务调度是可行的、有效的。

PFair processor scheduling algorithm based on time frame

When the PFair algorithm makes task scheduling, it may ignore the periodic tasks of different phases so that there will be problems of task migration among multiple threads and the waster of space and time. In view of the above problems, an improved PFair scheduling algorithm for the processor based on time frame is put forward. The algorithm, based on the characteristics of periodic task system, introduces the time frame to control and change the local periodic task scheduling and to limit task migration, so as to realize the improvement of the PFair algorithm. To assess the migration expense and fairness of the algorithm, comparison experiment between the ordinary PFair algorithm and improved ERfair algorithm proposed in this paper is carried out. The results show that, the improved ERfair algorithm can greatly reduce the times of task migration between different processors through scheduling in the time frame and partition control. The PFair scheduling algorithm for processor based on time frame can guarantee fairness, and also improve the efficiency of the system. It is feasible and effective when applied to the scheduling of multi-core processors.