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Questionnaire for the Course
Operating Systems and Networks
(Spring 2004)
Dr. J. Schönwälder
International University Bremen
March 22, 2004
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Introduction
6. Why does caching result in a speed-up most of the time?
In which situations will caching not work?
1. Describe the main purpose of an operating system.
7. Explain the different principles of I/O programming.
2. Explain the term “system software.” What does it include?
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3. What types of operating systems do you know and how
do these operating system types distinguish from each
other?
1. Explain the difference between a program and a process.
4. What is virtualization? Explain the main idea behind
virtual machines.
2. What is the difference between internal and external
process state?
5. Explain the difference between user-mode and systemmode on general purpose operating systems.
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Processes
3. What are typical process states and typical transitions
between these states.
6. What are the four ways to enter an operating system?
Which ones are synchronous from the perspective of an
application program?
4. Why are program counter and processor registers part
of the process control block?
7. Describe some operating system architectures and discuss their strengths and weaknesses.
5. How are processes created and destroyed in POSIX systems?
6. Explain the main differences between processes and
threads.
Hardware
7. What are the requirements for a good scheduler?
1. Many processor support multiple (at least two) privilege levels. Explain how privilege levels are supported
in CPUs and for which purpose they may be used by
operating systems.
8. Explain the difference between preemptive and nonpreemptive schedulers.
9. Explain the difference between deterministic and probabilistic schedulers.
2. What is a stack frame?
10. Explain the scheduling strategies FCFS, LPTF, SJF,
SRTF, and RR.
3. How are hardware interrupts handled? What does an
interrupt service routine usually do?
11. Use an example to explain the need for process synchronization.
4. Explain the term “memory hierarchy” and list typical
memory sizes in the memory hierarchy as well as their
access times.
12. What are critical section and race conditions?
5. Discuss the differences between write-through and
delayed-write in memory caches.
13. Describe the purpose of semaphores and how they can
be used to solve synchronization problems.
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14. How can semaphores be used to protect critical sections? Which programming errors can occur?
13. Explain the term “virtual memory”.
15. What is a synchronization monitor?
14. Name three loading and three replacement strategies
and discuss their advantages and disadvantages.
16. Compare the synchronization mechanisms present in
Java, POSIX pthreads, and Linux kernels.
15. What is a stack algorithm? Which important property
do stack algorithms have?
17. How can a message system be used to achieve synchronization?
16. Explain the term “working set model”.
18. Which synchronization mechanism is more powerful?
17. Describe situations in which the working set model
does not work very well?
19. Explain the term deadlock.
20. What are resource allocation graphs?
21. Name the necessary conditions for a deadlock.
22. What are safe and unsafe states? How can you determine whether a state is safe or unsafe?
23. Can deadlocks be prevented?
24. Is it possible to detect deadlocks? If yes, how can detected deadlocks be resolved?
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Memory
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File Systems
1. Name two storage media with random access and two
media with sequential access.
2. What are RAID discs? Explain the difference between
some of the RAID levels.
3. Discuss the concept of mounting a file system.
4. Explain the difference between hard links and soft links.
What are the advantages and disadvantages?
5. What is an inode? Which relationship exists between a
file name and an inode?
1. Explain the difference between absolute and relative
memory addresses.
6. Name some block allocation mechanisms. What are the
advantages and disadvantages?
2. What is the difference between logical and physical
memory addresses?
7. Explain the purpose of a file system virtualization.
3. What are the advantages of using logical addresses?
4. What is the role of the operating system play in the
translation of logical addresses to physical addresses?
5. Explain the term “swapping”.
6. What is the difference between internal and external
fragmentation?
7. Explain the term “segmentation”.
8. Name three positioning strategies and discuss their advantages and disadvantages.
9. What is compaction and in which context is it used?
10. Explain the term “paging”.
11. What are page faults? How are they handled by an operating system?
12. What are multi-level translation tables and inverse
translation tables? What are the advantages and disadvantages?