Question 6

A virtual memory is an economical method of extending the apparent size of the main memory by augmenting it with disk space. This augmentation can be implemented by using a paging scheme. Assume a program with SIX (6) virtual pages numbered from 0 to 5. A program references the virtual pages according to the following order: 1, 2, 3, 0, 1, 4, 0, 5, 1, 2, 3, 4, 2, 5

Compute the number of page faults with FOUR (4) page frames. Assume the frames are empty. Show your work using the following replacement policies:

i. Optimal(CO3, PO4 7 marks)

ii. Least Recently Used (LRU). (CO3, PO4 7 marks)

iii. According to answers in 6a(i). and 6a(ii).,

which policy is the best? Give your evidence. (CO3, PO4 2 marks)