2012级操纵系统试题.doc
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1、,Operating System Exam (For Grade 2000)Class Name Student ID 一、For each of the following statements, Choosing True or False (24 marks)1. Binary semaphores are those that are used by no more than two threads. 2. The Bankers algorithm is a way of preventing deadlock . 3. A multi-level indexed file per
2、mits faster random access than a contiguously allocated file. 4. An atomic operation is a machine instruction or a sequence of instructions that must be executed to completion without interruption. 5. Deadlock is a situation in which two or more processes (or threads) are waiting for an event that w
3、ill occur in the future. 6. Starvation is a situation in which a process is denied access to a resource because of the competitive activity of other, possibly unrelated, processes. 7. While a process is blocked on a semaphores queue, it is engaged in busy waiting. 8. Mutual exclusion can be enforced
4、 with a general semaphore whose initial value is greater than 1. 9. External fragmentation can be prevented (almost completely) by frequent use of compaction, but the cost would be too high for most systems. 10. A page frame is a portion of main memory. 11. The working set of a process can be change
5、d in response to actions by other processes. 12. Thrashing will never be a problem if the system has 1 GB of real memory. 13. A printer is an example of a logical resource. 14. Versions of OS/360 are still widely used today.15. When an executing process is stopped by the scheduler, it is said to be
6、blocked. 16.Interrupts are used to achieve a typical timesharing OS. 1.二进制信号量是指那些不能超过两个线程使用。2.银行家算法是防止死锁的方法。3.多层次的索引的文件允许快速比连续分配的文件的随机访问。4.一个原子操作是一个机器指令或必须完成而不会中断执行的指令序列。5.死锁是其中两个或多个进程 (或线程) 等将来会发生的事件的情况。6.饥饿是在其中一个过程被拒绝对资源的访问由于其他,可能不相关的过程的竞争活动的情况。7.虽然过程被阻止的信号量的队列,它正在忙着等待中。8 与一般的信号量,其初始的值大于 1,可以强制执行.
7、相互排斥。9.外部碎片可以 (几乎全部) 因频繁使用的压缩,但成本会太高了,大多数系统。10.页面框架是主内存的一部分。11.一个进程的工作集可以被其他进程更改响应操作。12 如果系统具有 1 GB 的实际内存.大个子决不会有问题。13.打印机是逻辑资源的示例。14.版本的 OS/360 今天仍在被广泛使用。15.当调度程序停止时正在执行的进程,据说被阻止。16.中断用于实现典型的分时操作系统。二、Multiple Choice Questions (30 marks)For each of the following questions, There is only one correct
8、answer. 1. What is the purpose of system calls?a) System calls allow user-level processes to gain resources from the operating system.b) System calls are the standard interface between a user process and a kernel process.c) System calls allow user-level processes to request services of the operating
9、 system.d) There is no real purpose to system calls.2. Threads belonging to the same process share thea) stackb) data sectionc) register setd) thread ID3. In Many-to-One thread model, What would happen if a thread in a multithreaded process makes a blocking system call ?a) the other threads of the p
10、rocess would continue to runb) the entire process would get blockedc) the blocking thread will get killedd) the blocking thread will never get to run again4. Which of the following Operating systems uses preemptive scheduling?a) Mac OS 8b) Windows 3.xc) Windows 2000d) DOS 6.05. A measure of the numb
11、er of processes completed per time unit is calleda) throughputb) waiting timec) response timed) CPU utilization6. One of the problems with priority scheduling isa) agingb) starvationc) process deathd) average waiting time7. Consider the following reference stringsI :0, 2, 4, 1, 1, 4, 5, 7 ; II :2, 3
12、, 2, 5, 6, 3, 2, 6If the FIFO page replacement algorithm with 3 frames is applied,which of the two reference strings will result in fewer page faults?a) reference string Ib) reference string IIc) both will have the same number of faultsd) cant determine from the given data.8.In a time-sharing system
13、, which of the following is the best criterion for CPU scheduling.a) Minimize CPU utilization b) Maximize CPU utilizationc) Maximize system throughputd) Minimize response time.9.The initial value of semaphore S is 2. if the value is -1 at present, how many processes are blocked on this semaphore .a)
14、 1 b) 2 c) 3 d) 410. A system is in a deadlock, if its resource allocation grapha) contains a cycleb) doesnt contain a cyclec) contains a cycle and there is just one instance of every resourced) has at least one outgoing edge from any one of the process nodes11. Preemption of resources can be enforc
15、ed to prevent occurrence of deadlocks, but this cant be applied to all the resource types, as preemption might leave the resource in an undetermined state. Which of the following resources cant hence be preempted?a) CPU registersb) memory spacec) tape drived) all of the above12. In the page replacem
16、ent scheme a reference string isa) the number of frames allocated to a processb) a string of memory referencesc) a string of I/O referencesd) the times spent on each page-fault service13. Which disk space allocation method supports direct access without external fragmentation?a) linearb) contiguousc
17、) linkedd) indexed14. A system is said to be _ if it can continue to function even when a node or nodes in the system fail.a) networkedb) distributedc) real timed) fault-tolerant15. Considering a system, which uses virtual memory. At what point can address binding be done?a) compile timeb) load time
18、c) execution timed) can be any of the above16. Which of the following is NOT associated with segments?a) two dimensional view of memoryb) fixed sizec) easy sharing of data or coded) external fragmentation17. Pages can be shared between processes having common reentrant code. Here reentrant code mean
19、sa) self-modifying codeb) code which keeps going in and out of memoryc) non-self-modifying coded) code containing shared data variables18. The time to position the head on the disk is thea) seek time.b) access time.c) transmission timed) rotational latency19. _ presents a uniform device-access inter
20、face to the I/O subsystem, much as system calls provide a standard interface between the application and the operating system.a) Kernelb) A set of device driversc) Busd) Operating system20. What is the name of the table containing information about all open files?a) file allocation tableb) open-file
21、 tablec) file tabled) file access table三、Consider the following set of processes: (10marks)Process Burst-Time PriorityP1 154P2 38P3 75P4 52P5 16P6 26The processes are assumed to have arrived in the order P1, P2, P3, P4, P5, P6, all at time 0.Use FCFS, SJF, Round Robin (quantum is 2), Priority(low nu
22、mbers have high priority). For each of the algorithms:1 Draw a Gantt chart2. What is the average waiting time for each of the scheduling algorithms?3. What is the average turnaround time for each of the scheduling algorithms?四、Consider a computer system with the following hardware characteristics. (
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