1. What are “caller-saved” and “callee-saved” registers? Where, and when are they saved / restored?
2. What are the various system calls used for managing processes? Briefly (in one or 2 lines) explain each of them.
3. What are they 3 main user-space memory regions of a process? What are the 3 main kernel space memory contents of each process?
4. What is a trapframe? Where does it reside?
5. Explain the differences between a mode switch and a context switch. When does mode switching occur? When does context switching occur?
6. What are the hardware features necessary for virtualizing the processor? What are the hardware features necessary for virtualizing memory?
7. What is the difference between long-term and short-term scheduling?
8. A process with a run-time of 12 time units that started at time 5 ended at time 36. What are the completion times, turnaround times and wait times for the process?
9. What are the 3 broad goals of process scheduling policies? Briefly describe the advantages and limitations of a) STCP, b) RR, and c) Ticket based approaches, towards achieving the 3 goals
10. How does MLFQ achieve short response time? How does it counter the possibility of starvation? How does it differentiate between I/O-bound and CPU-bound jobs?
11. How can a process game the system if MLFQ is used without anti-gaming measures? How does MLFQ address this?
12. How does CFS deal with different priorities for different processes?
13. What are the pros and cons of the 3 main strategies for virtualizing memory? (viz., base-and-bounds, segmentation, and page-tables).
14. What are the advantages of inverted page tables over multi-level page tables?
15. What is the purpose of the following bits in PTE entries – “use”, “valid” ,“present” and “dirty”. When, and by what (hardware or software) are these bits set/reset?
16. When implementing a multilevel paging scheme, what dictates the choice of PTE/PDE size? What dictates the choice of the page size?
17. Why is the optimal policy for cache management impractical?
18. Under what condition is the LRU policy a reasonable approximation for the optimal policy?
19. What makes the LRU impractical?
20. Does LRU (or the morse practical variant, clock algorithm) provide any benefit for random workloads? Why?
21. Briefly explain the clock-algorithm and why it is a practical alternative to LRU.
22. What are the pros and cons of data transfer techniques that involve destructive reads vs those that involve constructive reads
23. How are signals different from system calls? Give an example of a signal that can not be over-ridden
24. What are the different levels of persistence of IPC objects? What is the significance of different levels of persistence?
25. Can two threads of the same process access each other’s stack? Why (or why not)?
26. What are the pros and cons of hardware vs software locks?
27. What are the pros and cons of spin locks vs mutex locks
28. Explain the Peterson-Dekker algorithm for software locks
29. What is the main purpose of a condition variable? Why do we need a lock to use a CV?
30. Explain the need for 2 CVs in the solution to the producer consumer problem with arbitrary buffer size
31. What is the purpose of each of the 3 semaphores in the solution to the p-c problem?
32. What are the 3 layers of the file-system within the OS kernel? Can you give an example of a fourth layer outside the kernel?
33. What is disk skew? Why is it needed?
34. Compute the random and sequential throughputs for a hard-disk with the following specs: 10000 RPM, 5 ms seek time, 150 MB/sec data transfer rate
35. What is the system call used for deleting a file? Explain the functioning of the system call.
36. Is there a relationship between the throughput of a disk and the speed at which one can seek 1000 bytes ahead in a file? Why (or why not?)
37. What are the different ways in which a shared entry can be created in an OFT?
38. Why are hard-links to directories ill-advised?
39. Explain the sequence of block reads and block writes that occur for the following 2 scenarios:
    1. Create a hardlink /home/joe/readmetoo.txt for a file /home/joe/readme.txt
    2. Create a soft-link /home/joe/readmetoo.txt for a file /home/joe/readme.txt
40. What are main advantages of SSD compared to hard disks
41. Why do OSes attempt to group random reads and writes (to the extent possible) when using hard disk as storage medium. Is the strategy of grouping reads and writes advantageous for SSDs too?
42. If magnetic disturbances induced by a cosmic ray flipped some bits of a hard disk, can such errors be caught by running fsck?
43. What is the complete mediation in the context of computer security? Why is it needed?

Link of the BOOK

http://pages.cs.wisc.edu/~remzi/OSTEP/