CS439: Principles of Computer Systems

Discussion Section 8 Problem Set

Due in Section on Friday, March 27, 2026

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.

Is it fundamentally necessary to store on disk the information about the unallocated disk sectors? Explain why.

The operating system gives memory to the heap memory manager k page(s) at a time. Why?

Consider a process that dynamically allocates objects A, B, C, and D. After some times has passed, objects B and D are reachable, but A and C are not. Assuming a semi space garbage collection algorithm, what are the contents of the heap after the next garbage collection pass? Be sure to write them in order.

Pooh Software Ltd. is selling a file system that uses a UNIX-like file system with multi-level indexing. For more reliability, the inode array is actually replicated on the disk in two different places. The intent is that if one or a group of sectors that are storing either replica of the array become bad, the system can always recover from the replica. Discuss the effect of having this replicated data structure on performance.

Some file allocation schemes limit the size of the file whether or not there is enough space for a larger file. Which ones and why?

Which file allocation scheme that we studied is most similar to paging? segmentation?