On-Line Scheduling Algorithms for QoS Control

摘要

Since the optional portions of imprecise tasks can be traded for their deadlines and, the required quality of service (QoS), the resulting quality of executing tasks in imprecise computation model can be controlled by different strategics of the scheduling algorithms. This paper presents three. algorithms for scheduling on-line, preemptive, imprecise tasks on single-processor systems. The purpose of this work is threefold. Firstly, it intends to cm-ploy imprecise computation techniques for QoS control of task execution. Secondly, it aims to provide an adjustable scheduling scheme for improving the schedulability. Thirdly, it proposes to offer a set of flexible tools for task scheduling based on different QoS requirements. By trickily applying the, k-tasks-look-ahead substitutable check, we devise three on-line scheduling algorithms for QoS control. Additionally, the parameter in such check is adjustable to enhance the schedulability. Our algorithms are optimal w.r.t. the total error minimization under the feasible mandatory constraint.