What is a page fault?

(b) How is a page fault handled if it is triggered by a process issuing a write for which it has permission on a machine with ample free memory at the point the page fault occurs? [6 marks]

(c) If the machine does not have sufficient free memory at the point that the page fault occurs, a victim page must be selected for replacement. Describe the ideal algorithm for handling this case, and explain why it cannot be implemented. [2 marks]

(d) Now describe a practical algorithm for selecting a victim page for replacement. In your answer you should discuss its performance, storage and time overheads, indicating any assumptions you make. [6 marks]

(e) What is B´elady’s Anomaly? Can the algorithm described in Part (d) suffer from it? Justify your answer. (Note: You are not required to demonstrate an instance of B´el´ady’s Anomaly occurring.) [4 marks]