第五章习题及答案
《第五章习题及答案》由会员分享,可在线阅读,更多相关《第五章习题及答案(1页珍藏版)》请在装配图网上搜索。
1、精选优质文档-倾情为你奉上5.2 Discuss how the following pairs of scheduling criteria conflict in certain settings.a. CPU utilization and response timeb. Average turnaround time and maximum waiting timec. I/O device utilization and CPU utilizationAnswer:a. CPU utilization and response time: CPU utilization is inc
2、reased if the overheads associated with context switching is minimized. The context switching overheads could be lowered by performing context switches infrequently. This could however result in increasing the response time for processes.b. Average turnaround time and maximum waiting time: Average t
3、urnaround time is minimized by executing the shortest tasks first. Such a scheduling policy could however starve long-running tasks and thereby increase their waiting time.c. I/O device utilization and CPU utilization: CPU utilization is maximized by running long-running CPU-bound tasks without perf
4、orming context switches. I/O device utilization is maximized by scheduling I/O-bound jobs as soon as they become ready to run, thereby incurring the overheads of context switches.5.3 Consider the exponential average formula used to predict the length of the next CPU burst. What are the implications
5、of assigning the following values to the parameters used by the algorithm?a. = 0 and 0 = 100millisecondsb. = 0.99 and0= 10millisecondsAnswer: = 0 and 0 = 100milliseconds, the formula always makes a prediction of 100 milliseconds for the next CPU burst. When= 0.99 and0= 10milliseconds, the most recen
6、t behavior of the process is given much higher weight than the past history associated with the process. Consequently, the scheduling algorithm is almost memory-less, and simply predicts the length of the previous burst for the next quantum of CPU execution.5.9 Consider a preemptive priority schedul
7、ing algorithm based on dynamically changing priorities. Larger priority numbers imply higher priority. When a process is waiting for the CPU (in the ready queue, but not running), its priority changes at a rate; when it is running, its priority changes at a rate. All processes are given a priority of 0 when they enter the ready queue. The parametersandcan be set to give many different scheduling algorithms.a. What is the algorithm that results from 0?b. What is the algorithm that results from 0?Answer:a. FCFSb. LIFO专心-专注-专业
- 温馨提示:
1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 装配图网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。