Assume there are only 4 page frames in the physical memory, for the following reference string:
1, 2, 3, 4, 5, 3, 4, 1, 6, 7, 8, 7, 8, 9, 7, 8, 9, 5, 4, 5, 4, 2, 8.
a) What is minimum number of page faults for an optimal page replacement strategy? Please show how the page is placed and how page faults occur.
b) How many page faults occur using LRU? Please show how the page is placed and how page faults occur.