arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1810.08342cs.DC
收藏

多处理机上实时的任务在线调度的流网络模型

Flow Network Models for Online Scheduling Real-time Tasks on Multiprocessors

Hyeonjoong Cho, Arvind Easwaran

摘要:

我们考虑流网络模型来解决多处理机实时的【形】任务调度问题。使用流网络模型或其一般形式,线性规划(LP)制定,为问题并不新鲜。然而,以前的工作有局限性,例如,它们被归类为离线调度技术,因为它们建立了流网络模型或考虑很长时间间隔的LP问题。在本研究中,我们提出如何建构多处理器上周期性实时的【形】任务线上排程的流网路模型。我们的核心思想是只为当前调度时间的活动任务实例构建流网络,同时保证未来任务实例的最优调度存在。最优调度是指当给定任务的总利用率需求不超过总处理能力时,所有实时的【形】任务都能在截止期内完成。然后,我们提出了基于流网络模型的多项式时间调度算法。有利地,流网络模型允许在特定时间间隔内不公平地收集任务工作负载,而不会失去最优性。因此,它导致我们设计三个不公平,但最优的调度算法上的连续和离散时间模型。特别是,我们的不公平,但最优的离散时间模型的调度算法是,据我们所知,在问题域中的第一。我们的实验表明,它显着减少调度开销,即,抢占的数量减少,跨处理器的任务迁移的数量相当。

英文摘要:

We consider the flow network model to solve the multiprocessor real-time task scheduling problems. Using the flow network model or its generic form, linear programming (LP) formulation, for the problems is not new. However, the previous works have limitations, for example, that they are classified as offline scheduling techniques since they establish a flow network model or an LP problem considering a very long time interval. In this study, we propose how to construct the flow network model for online scheduling periodic real-time tasks on multiprocessors. Our key idea is to construct the flow network only for the active instances of tasks at the current scheduling time, while guaranteeing the existence of an optimal schedule for the future instances of the tasks. The optimal scheduling is here defined to ensure that all real-time tasks meet their deadlines when the total utilization demand of the given tasks does not exceed the total processing capacity. We then propose the flow network model-based polynomial-time scheduling algorithms. Advantageously, the flow network model allows the task workload to be collected unfairly within a certain time interval without losing the optimality. It thus leads us to designing three unfair-but-optimal scheduling algorithms on both continuous and discrete-time models. Especially, our unfair-but-optimal scheduling algorithm on a discrete-time model is, to the best of our knowledge, the first in the problem domain. We experimentally demonstrate that it significantly alleviates the scheduling overheads, i.e., the reduced number of preemptions with the comparable number of task migrations across processors.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑