Given that main memory is composed of three page frames for public use and that a program requests pages in the following order.
dcbadcedcbae
a.) using the FIFO range removal algorithm, do a page trace analysis indicating page faults with asterisks (*). then compute the failure and success ratios.
b.) increase the size of memory so it contains four page frames for public use. Using the same page request as above and FIFO, do another page trace analysis and compute the failure and success ratio.
c.) did the result correspond with you intuition? explain.
a) To analyze the page trace using the FIFO algorithm with three page frames, we will simulate the process step by step:
Page Trace: dcbadcedcbae
Page Frames: _ _ _
1. d* (Fault) -> d _ _
2. c* (Fault) -> d c _
3. b* (Fault) -> d c b
4. a* (Fault) -> a c b
5. d (Success) -> a c b
6. c (Success) -> a c b
7. e* (Fault) -> a c e
8. d (Fault) -> a c e
9. c (Fault) -> a c e
10. b (Success) -> a c e
11. a (Success) -> a c e
12. e (Success) -> a c e
Failure Ratio: Number of Page Faults / Total Page Requests = 6 / 12 = 0.5 (50%)
Success Ratio: Number of Successful Page Requests / Total Page Requests = 6 / 12 = 0.5 (50%)
b) To analyze the page trace using the FIFO algorithm with four page frames, we will simulate the process with an additional page frame:
Page Trace: dcbadcedcbae
Page Frames: _ _ _ _
1. d* (Fault) -> d _ _ _
2. c* (Fault) -> d c _ _
3. b* (Fault) -> d c b _
4. a* (Fault) -> d c b a
5. d (Success) -> d c b a
6. c (Success) -> d c b a
7. e* (Fault) -> d c b e
8. d (Fault) -> d c b e
9. c (Fault) -> d c b e
10. b (Failure) -> d c b e
11. a (Failure) -> d c b e
12. e (Success) -> d c b e
Failure Ratio: Number of Page Faults / Total Page Requests = 5 / 12 = 0.417 (41.7%)
Success Ratio: Number of Successful Page Requests / Total Page Requests = 7 / 12 = 0.583 (58.3%)
c) The result corresponds with intuition. When the size of memory was increased from three to four page frames, the failure ratio decreased and the success ratio increased. This makes sense because increasing the number of page frames allows more pages to be resident in memory, reducing the chances of a page fault.