Operating Systems Questions

Section I - Problems

 

The exam questions may be similar to some of the following questions from the text book. The most representative questions are:

IV-th Edition of the text book.

Chap. 7

Chap. 8

Chap. 9

Chap. 10

Chap. 11

Chap. 12

4, 5, 6, 8, 9, 11, 12

1, 2, 4, 5, 7, 8, 9, 10, 11

1, 3, 5, 6, 7, 8, 9, 11, 16, 17, 18, 20

6, 7, 8,

1, 6,

2, 5, 6, 7

 

V-th Edition of the text book.

Chap. 7

Chap. 8

Chap. 9

Chap. 10

Chap. 11

Chap. 13

4, 5, 6, 8, 9, 13, 14

1, 2, 3, 5, 7, 8, 9, 10, 11

1, 3, 5, 6, 7, 8, 9, 11, 16, 17, 18, 20

6, 7, 8,

1, 6,

2, 3, 5, 8, 9

 

 

Other possible types of questions:

 

  1. Calculate the effective access time if the page fault service time is 25ms, a memory access takes 100ms and one of each four pages will generate a page fault (on average).
  2. Consider a file system using a Unix-like protection mechanism. How would you change the permissions of a file so that the owner is able to read, write and execute the file, the other members of the same group can only read and execute the file and everybody else can only execute it.
  3. Consider a system which uses 512Kbytes blocks and
  1. contiguous
  2. linked
  3. indexed allocation with two levels of indirection

Consider a file which starts at physical address 100000 and is 2000Kbytes.

    1. Calculate the physical address for the logical address 1500 in each of the case a-c above.
    2. Explain how the physical address is used in each case.
  1. Consider a file system using an Unix-like indexed allocation mechanism with three levels of indirection. What is the maximum size of a file in this operating system if there are 10 direct pointers, all indirection tables have 512 elements and a block has 4Kbytes,?
  2. Consider an operating system which uses a bit array to keep track of the free and allocated blocks. What can you tell about each of the situations below? Does it represent a consistent situation? If yes, why? If no, why not and what can you do to solve the problem?

Block #

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

In use

1

1

0

1

0

1

1

0

1

0

1

1

1

0

0

1

Free

0

0

1

0

1

0

1

1

0

1

0

0

0

1

1

0

Block #

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

In use

1

1

1

0

0

0

1

0

1

0

1

1

0

0

0

1

Free

0

0

0

1

1

1

0

1

0

1

0

0

1

1

1

0

Block #

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

In use

1

1

0

1

0

1

1

1

0

1

0

0

1

0

0

1

Free

1

0

1

0

0

0

0

0

1

0

1

1

0

1

1

0

 

Sections 8.6, 8.7 and 10.5 are not included in the topics that will be tested in the final exam.