课程名称︰作业系统
课程性质︰必修
课程教师︰郭大维
开课学院：电资学院
开课系所︰资工系
考试日期（年月日）︰2014/4/30
考试时限（分钟）：180
是否需发放奖励金：是
（如未明确表示，则不予发放）
试题 :
The exam is 180 minutes long. The total score is 103pts. Please read the
questions carefully.
1.Terminologies (24pts).
a. Booting
b. Interrupt Vector
c. Cache Coherency
d. Platform as a service (PaaS) in Cloud Computing
e. A Modular Kernel (Hint: OS Structure)
f. Data Parellelism in Multicore Programming
g. Rate Monotonic Scheduling
h. Deterministic Modeling
2. Please answer the following questions regarding the designs of operating
systems: (20pts)
a. There are two conflicting goals in the designs of operating systems.
What is the other one, beside "convenient for the users" ? (3pts)
b. Which one of the following actions/events is belonging to or might
result in software interrupts: System calls, child termination,
mouse clicking, invalid memory access. (8pts)
c. Consider the implementation of virtual machines in which operating
systems run on the top of the virtual machine software (or referred
to as the hypervisor). Is an operating system running in the user
mode or kernel mode? (3pts)
d. Please give me 2 advantages of virtual machines, beside system
consolidation and easy in system development/deployment. (6pts)
3. ANSI C refers to the family of successive standards published by ANSI for
the C programming language. Please compare difference (or provide the
purpose difference) between POSIX and ANSI C. (5pts)
4. Please answer the following questions for task scheduling. (14pts)
a. Is the "Swapper" a short-term or mid-term scheduler?
b. In Unix, the process control block PCB[] of a process consists of
proc[] and .u, where the attributes in .u are those needed when the
process is running, and the attributes in proc[] are those needed
all the time. Please indicate which one should be in .u : file[],
task priority, pid, signal disposition, and task state. You must
provide explanation to receive any credits. (10pts)
5. Consider message passing and shared memory for inerprocess communication.
Is "Pipe" considered one for message passing or shared memory ? Is "Pipe"
direct or indirect communication ? Is it "synchronous" or "asynchronous" ?
for a reader or a writer of the communication in Unix. You must provide
explanation to receive any credits. (12pts)
6. Kernel-level threads are superior than uer-level threads do in many ways.
What is the main disadvantage of kernel-level threads ? With OpenMP in
program development, shall we prefer kernel-level or user-level threads ?
You must provide explanation to receive any credits. (8pts)
7. Please answer the following questions for process scheduling. Explanation
is needed to receive any credits. (15pts)
a. Given 3 processes P1, P2, and P3 with CPU burst time 5, 6, 7,
respectively. Suppose that the 3 processes arrive at time 0, and P1
and P3 are the first and the last processes in the ready queue,
respectively. What is the average waiting time in running the 3
processes under the Round-Robin Scheduling with the time slice
equal to 3. (5pts)
b. Consider FCFS and Round-Robin Scheduling. If process are only of
CPU burst and all arrive at time 0, do FCFS and Round-Robin
Scheduling with time slice = 1 always have the same total waiting
time in running all processes ? Prove your answer. (5pts)
c. Suppose that the variance of the tunaround time is the cirterion in
process scheduling. Shall we have a small time slice for a better
variance turnaround time when all processes arrive at time 0? (5pts)
8. Please explain why the Completely Fair Scheduling (CFS) of Linux V2.6
favors I/O tasks. (5pts)