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Name HW5: Virtual Memory and Storage Scheduling 1) Given a 3 frame VMM and the p

ID: 3701241 • Letter: N

Question

Name HW5: Virtual Memory and Storage Scheduling 1) Given a 3 frame VMM and the page request sequence below (it's the top row), perform the VMM First In First Out page replacement policy (complete the table) to determine the total number of page faults for the sequence F1 2 342 4 5 1 637 5 3 26 6 2 4 5 3 2151 6 34 2 1 How many page faults? 2) Given a 4 frame VMM and the page request sequence below (it's the top row), perform the VMM Least Recently Used page replacement policy (complete the table) to determine the total number of page faults for the sequence F1 2 34 24 51 637 53 26 6245 3 215 634 2 1 How many page faults? 3) Given a 3 frame VMM and the page request sequence below (it's the top row), perform the VMM Optimal page replacement policy (complete the table) to determine the total number of page faults for the F1 2 342 4 5 1637 5 3 26 6 2 4 5 3 2151 6 3 4 21 How many page faults?

Explanation / Answer

1. FIFO

F

1

2

3

4

2

4

5

1

6

3

7

5

3

2

6

6

2

4

5

3

2

1

5

1

6

3

4

2

1

0

1

1

1

4

4

4

4

4

6

6

6

5

5

5

5

5

5

4

4

4

2

2

2

2

6

6

6

2

2

1

2

2

2

2

2

5

5

5

3

3

3

3

2

2

2

2

2

5

5

5

1

1

1

1

3

3

3

1

2

3

3

3

3

3

1

1

1

7

7

7

7

6

6

6

6

6

3

3

3

5

5

5

5

4

4

4

fault

x

X

x

x

X

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

Page fault = 23

2. LRU

F

1

2

3

4

2

4

5

1

6

3

7

5

3

2

6

6

2

4

5

3

2

1

5

1

6

3

4

2

1

0

1

1

1

4

4

4

4

4

6

6

6

5

5

5

6

6

6

6

5

5

5

1

1

1

1

1

4

4

4

1

2

2

2

2

2

2

1

1

1

7

7

7

2

2

2

2

2

2

3

3

3

5

5

5

3

3

3

1

2

3

3

3

3

5

5

5

3

3

3

3

3

3

3

3

4

4

4

2

2

2

2

6

6

6

2

2

fault

x

X

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

Page fault = 23

3. OPTIMAL

F

1

2

3

4

2

4

5

1

6

3

7

5

3

2

6

6

2

4

5

3

2

1

5

1

6

3

4

2

1

0

1

1

1

1

1

1

1

1

6

3

3

3

3

3

6

6

6

4

4

3

3

3

3

3

3

3

4

2

2

1

2

2

2

2

2

2

2

2

2

7

7

7

2

2

2

2

2

2

2

2

1

1

1

1

1

1

1

1

2

3

4

4

4

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

6

6

6

6

6

fault

x

X

x

x

x

x

x

x

x

x

x

x

x

x

x

x

Page fault = 16

4. Disk Scheduling – FCFS

movement

Head movement count

61->97

36

97->38

59

38->47

9

47->13

34

13->73

60

73->34

39

Total head movement = 240

5. SSTF

Movement

Head movement count

61->73

12

73->97

24

97->47

50

47->38

9

38->34

4

34->13

21

Total head movement = 120

6. LOOK

Movement

Head movement count

61->47

14

47->38

9

38->34

4

34->13

21

13->73

60

73->97

24

Total head movement = 132

F

1

2

3

4

2

4

5

1

6

3

7

5

3

2

6

6

2

4

5

3

2

1

5

1

6

3

4

2

1

0

1

1

1

4

4

4

4

4

6

6

6

5

5

5

5

5

5

4

4

4

2

2

2

2

6

6

6

2

2

1

2

2

2

2

2

5

5

5

3

3

3

3

2

2

2

2

2

5

5

5

1

1

1

1

3

3

3

1

2

3

3

3

3

3

1

1

1

7

7

7

7

6

6

6

6

6

3

3

3

5

5

5

5

4

4

4

fault

x

X

x

x

X

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x