CPU computer systems is a very important resource, this chapter introduces proce...

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CPU是计算机系统中一个十分重要的资源，本章主要介绍处理机的调度目标、策略以及评价方法等。因为处理机调度程序不可能选择全部驻留在外存的进程，因此，在调度一个进程占有处理机之前，系统必须按某种策略把外存中处于后备状态的作业选择出来，并创建进程和分配内存，为进程执行准备必需的资源。这一步称为作业调度或高级调度。作业调度的目标是尽量做到公平合理，能执行尽可能多的作业、尽快地响应时间以及高的设备利用率等。任一调度算法要同时满足这些调度目标是不可能的。大多数操作系统都是根据用户需要而采用兼顾某些目标的方法。比较常用的作业调度算法有：FCFS（先来先服务）、方法、SJP(最短作业优先)法、HRN(最高响应比)法等。这-CPU computer systems is a very important resource, this chapter introduces processor scheduling objectives, strategies and evaluation methods. Because the processor scheduling procedures could not choose Disk presence in all the process, and therefore, in the process of scheduling a possession before the processor, the system must be some kind of strategy to Disk backup were at the operational state of choice out and the process of creation and distribution of memory, the process of preparing the implementation of the necessary resources. This step as job scheduling or senior scheduling. Job Scheduling goal is to try to make it fair and reasonable to carry out the operation as much as