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Demand paging problems (page replacement algorithms): Reference string 1 7 5 4 0

ID: 3554276 • Letter: D

Question

Demand paging problems (page replacement algorithms):

Reference string

1

7

5

4

0

1

4

7

3

6

5

0

4

7

3

2

1

Physical frame 0

Physical frame 1

Physical frame 2

Physical frame 3

Page faults

Victim frames

1. For the following reference string apply the FIFO page replacement algorithm.

2. For the following reference string apply the OPT page replacement algorithm.

3. For the following reference string apply the LRU page replacement algorithm.

4. For the following reference string apply the LFU page replacement algorithm.

Reference string

1

7

5

4

0

1

4

7

3

6

5

0

4

7

3

2

1

Physical frame 0

Physical frame 1

Physical frame 2

Physical frame 3

Page faults

Victim frames

Explanation / Answer

initially frames are free. so first 4 page placements are considered as page faults. if it is the case, first 4 pages are already placed, we have deduct 4 from total no. of page faults.

Reference string

1

7

5

4

0

1

4

7

3

6

5

0

4

7

3

2

1

Physical frame 0

1

1

1

1

0

0

0

0

0

6

6

6

6

7

7

7

7

Physical frame 1

7

7

7

7

1

1

1

1

1

5

5

5

5

3

3

3

Physical frame 2

5

5

5

5

5

7

7

7

7

0

0

0

0

2

2

Physical frame 3

4

4

4

4

4

3

3

3

3

4

4

4

4

1

Page faults

1

2

3

4

5

6

6

7

8

9

10

11

12

13

14

15

16

Victim frames

0

1

2

3

0

1

2

3

0

1

2

3

Reference string

1

7

5

4

0

1

4

7

3

6

5

0

4

7

3

2

1

Physical frame 0

1

1

1

1

1

1

1

1

3

6

5

5

5

5

5

5

5

Physical frame 1

7

7

7

7

7

7

7

7

7

7

7

7

7

3

3

3

Physical frame 2

5

5

0

0

0

0

0

0

0

0

0

0

0

0

1

Physical frame 3

4

4

4

4

4

4

4

4

4

4

4

4

2

2

Page faults

1

2

3

4

5

5

5

5

6

7

8

8

8

8

9

10

11

Victim frames

2

0

0

0

1

2

3

Reference string

1

7

5

4

0

1

4

7

3

6

5

0

4

7

3

2

1

Physical frame 0

1

1

1

1

0

0

0

0

3

3

3

3

4

4

4

4

1

Physical frame 1

7

7

7

7

1

1

1

1

6

6

6

6

7

7

7

7

Physical frame 2

5

5

5

5

5

7

7

7

7

0

0

0

0

2

2

Physical frame 3

4

4

4

4

4

4

4

5

5

5

5

3

3

3

Page faults

1

2

3

4

5

6

6

7

8

9

10

11

12

13

14

15

16

Victim frames

0

1

2

0

1

3

2

0

1

3

2

0

Reference string

1

7

5

4

0

1

4

7

3

6

5

0

4

7

3

2

1

Physical frame 0

1

1

1

1

0

0

0

0

3

6

5

0

0

0

3

2

2

Physical frame 1

7

7

7

7

1

1

1

1

1

1

1

1

1

1

1

1

Physical frame 2

5

5

5

5

5

7

7

7

7

7

7

7

7

7

7

Physical frame 3

4

4

4

4

4

4

4

4

4

4

4

4

4

4

Page faults

1

2

3

4

5

6

6

7

8

9

10

11

11

11

12

13

13

Victim frames

0

1

2

0

0

0

0

0

0

Reference string

1

7

5

4

0

1

4

7

3

6

5

0

4

7

3

2

1

Physical frame 0

1

1

1

1

0

0

0

0

0

6

6

6

6

7

7

7

7

Physical frame 1

7

7

7

7

1

1

1

1

1

5

5

5

5

3

3

3

Physical frame 2

5

5

5

5

5

7

7

7

7

0

0

0

0

2

2

Physical frame 3

4

4

4

4

4

3

3

3

3

4

4

4

4

1

Page faults

1

2

3

4

5

6

6

7

8

9

10

11

12

13

14

15

16

Victim frames

0

1

2

3

0

1

2

3

0

1

2

3

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