2012级操作系统试题

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 Banker's algorithm is a way of preventing deadlock .

3. A multi-level indexed file permits 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 will 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 semaphore's queue, it is engaged in busy waiting.

8. Mutual exclusion can be enforced 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 changed 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 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.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 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 system.

d) There is no real purpose to system calls.