MC78 Homework 3 (Fall 1996)

Due: October 10, 1996

Do problem 8 from chapter 3 of the textbook; it is on page 142.
Do problem 11 from chapter 3 of the textbook; it is on page 142.
Do problem 19 from chapter 3 of the textbook; it is on page 143.
Do problem 26 from chapter 3 of the textbook; it is on page 144.
Consider three computer systems: a batch processing system, an interactive timesharing system, and a single-user workstation. Now consider two options for page-replacement. One is a global replacement algorithm, in which all the processes' pages are considered for replacement to free up page frames when necessary, using an LRU policy or something similar. The other is a local replacement algorithm, in which each process has its own pool of page frames, and when it needs a to page something in replaces one of its own pages, again using LRU or something similar. In this latter option, the size of each process's pool of page frames is adjusted using the page fault frequency (PFF) allocation algorithm, as described on page 122. As described there, if not enough page frames are available to satisfy the PFF algorithms demand for all the processes, one of them is completely swapped out until memory demand recedes.
Discuss which of the three computer systems is best suited to the global replacement algorithm, and which is best suited to the local algorithm with PFF allocation.