非精确计算中基于反馈的CPU在线调度算法

摘要

With an increasing requirement of more flexible real-time applications, e.g. multimedia servers in home networks and real-time database servers, a real-time process scheduler using Worst-Case Execution Time (WCET) is inefficient for optimizing performance. Some soft and firm real-time models have been proposed to deal with this situation. This paper presents a feedback control approach for scheduling processes with imprecise computation, a firm real-time model to produce approximate result of an acceptable quality when the exact result of the desired quality cannot be obtained in time. By introducing feedback control to process scheduling, our approach aims to bind the deadline missing ratio under a varying system workload to reach a tradeoff between the deadline missing ratio and result precision.%随着家庭网络中的多媒体服务器和实时数据库服务器这类应用对实时的灵活性的要求不断增加,传统实时基于最长执行时间(WCET)的调度算法已经不能满足它们对性能优化的要求.因此,产生了一些软实时的调度算法来解决这些问题.提出了一种由反馈环节控制的实时调度算法,该算法用于调度能使用不精确计算模型描述的进程.算法可以在各种负载条件下,通过在调度过程中引入的反馈控制,在计算精度和计算时间上直接取得折衷,将进程错过时限的比例控制在预定范围内.