CS439: Principles of Computer Systems

Discussion Section 6 Problem Set Solutions

Due in Section on Friday, October 17, 2025

The problem set must be completed before section and brought to section. To ensure that your problem set is turned in correctly and that you receive credit for discussion section, you must follow these guidelines exactly.

Include the following header at the top of your file:

Discussion Section Problem Set #:
Student Name:
EID:

You may either type your answers or write them by hand, but you must have a copy with you in discussion section.

In discussion section, your TA will check that you made a good effort on the problem set, you are participating in the discussions in section, and you are ready and able to answer when called upon. If all of those are true, you will receive credit for discussion section that day. Note that a "good effort" on the problem set includes that all answers are in words unique to you and not copied from anywhere else, including the slide deck.

What causes a page fault? What is the end result for the running process?
What causes a memory exception? What is the end result for the running process?
Pages have (at least) the following three bits associated with them: the resident bit, the clock/reference bit, and the dirty bit. Describe each bit and its use.
What is the difference between global and local page replacement policies? Name a disadvantage of each.
Name two advantages of using small pages and two advantages of using large pages in a paging mechanism. Why are page sizes growing in paging memory systems?
Consider a program with seven virtual pages numbered from 0 to 6 references its pages in the order:

0 1 3 6 2 4 5 2 5 0 3 1 2 5 4 1 0

Using clock page replacement algorithm with 4 frames and assuming demand paging, compute the number of page faults and show the state of frames (pages in frames and value of clock bit) after each page access.