CS 471
Operating Systems
Challenge Test
Time 2 & 1/2 hours
Open Book & Notes
Q1:
UNIX has many systems calls. List two of UNIX system calls that deals with the following
components of the operating system:
1. Process Control
2. Files Manipulation
3. Interprocess Communications.
Q2:
In operating systems a process is created and then eventually is terminated.
In between creation and termination it changes states.
List the names of 3 such states.
Q3:
Consider the following three processes submitted in the order:
P1, P2 and P3 with estimated CPU times: 4, 3 and 2. Compute the average waiting time if
these 3 processes are scheduled according to:
1) FCFS:
2) SJF:
3) RR with Quantum time = 2:
Q4:
Fill in the number of page faults in the following matrix, assuming the following page
reference string:
5 6 1 0
Working set
size
Page
Replacement
Algorithm
Optimal
Random
FIFO
LRU
LFU
MFU
1
1
6 0 8
6
2
2
10
Q5:
Consider the following access matrix.
1. Is it possible for D1 to access the laser printer? Explain.
2. Is it possible for D1 to access F2? Explain.
Q6:
Calculate the total head movement for servicing the following request Queue according to
the specified disk I/O scheduling algorithms.
Request Queue (cylinder range 0-100):
83 37 14 24 65
Head pointer: cylinder 0
Disk Scheduling
Algorithm
Total Head
Movement
FCFS
SSTF
C-LOOK
Q7:
The following is the typical information kept about a file in UNIX.
Assume the following:
 A data block pointer = 10 bytes.
 Number of direct blocks = 10
 A block size = 1000 bytes.
Calculate the maximum possible file size in blocks.