Question

Show which pages are resident under the page-fault-frequency replacement algorithm with d=3. Indicate when page faults occur.

a) True
b) False

Answer 1

The page-fault-frequency replacement algorithm with d=3 prioritizes replacing the page that has been accessed the fewest times in a given window of size d. Page faults occur when a requested page is not in memory. The algorithm helps optimize memory usage by keeping frequently accessed pages resident in memory.

Step-by-step explanation:

The page-fault-frequency replacement algorithm with d=3 prioritizes replacing the page that has been accessed the fewest times in a given window of size d. Whenever there is a page fault, meaning a requested page is not in memory, the algorithm will replace the page that has been accessed the fewest times within the window. This algorithm helps to optimize memory usage by keeping the most frequently accessed pages resident in memory.

For example, let's say we have a page reference string: 1, 2, 3, 1, 4, 5, 6, 1, 2, 7. If the window size is d=3, the pages resident in memory after each access would be:

1. 1 (page fault)
2. 1, 2 (page fault)
3. 1, 2, 3 (page fault)
4. 2, 3, 4 (page fault)
5. 3, 4, 5 (page fault)
6. 4, 5, 6 (page fault)
7. 5, 6, 7 (page fault)
8. 5, 6, 7 (page fault)
9. 5, 6, 7 (no page fault)
10. 5, 6, 7 (no page fault)

So, in this example, the pages resident under the page-fault-frequency replacement algorithm with d=3 at each step are as shown above. Page faults occur whenever a requested page is not in memory.