CPU Scheduling Complete Test Bank Ch.5 10th Edition

Chapter 5

Multiple Choice Questions

1. The ready queue can be implemented as a _______________.

A) FIFO queue

B) priority queue

C) tree

D) unordered linked list

E) all of the above

Section: 5.1.2

Difficulty: Easy

2. Which of the following circumstances can cooperative scheduling take place?

A) when a process switches from the running state to the waiting state

B) when a process switches from the running state to the ready state

C) when a process switches from the waiting state to the ready state

D) none of the above

Section: 5.1.3

Difficulty: Easy

3. Which of the following circumstances can preemptive scheduling take place?

A) when a process switches from the running state to the waiting state

B) when a process switches from the waiting state to the ready state

C) when a process terminates

D) none of the above

Section: 5.1.3

Difficulty: Easy

4. Which of the following items does not belong to the function of a dispatcher?

A) switching context from one process to another

B) selecting a process among the available ones in the ready queue

C) switching to user mode

D) jumping to the proper location in the user program to resume that program

Section: 5.1.4

Difficulty: Medium

5. Assume process P₀ and P₁ are the process before and after a context switch, and PCB₀ and PCB₁ are respectively their process control block. Which of the following time units are included inside the dispatch latency?

A) P₀ executing

B) save state into PCB₀, and restore state from PCB₁

C) P₁ executing

D) all of the above

Section: 5.1.4

Difficulty: Medium

6. Which of the following criteria is more important for an interactive system?

A) CPU utilization

B) Response time

C) Turnaround time

D) Throughput

Section: 5.2

Difficulty: Easy

7. Which of the following criteria is more important from the point of view of a particular process?

A) CPU utilization

B) Response time

C) Turnaround time

D) Throughput

Section: 5.2

Difficulty: Easy

8. For interactive systems, it is more important to minimize ________.

A) the average response time

B) the average turnaround time

C) the variance in response time

D) the waiting time

Section: 5.2

Difficulty: Easy

9. Which of the following scheduling algorithm may suffer from convoy effect?

A) SJF

B) FCFS

C) RR

D) Multilevel queue

Section: 5.3.1

Difficulty: Easy

10. Which of the following scheduling algorithms must be nonpreemptive?

A) SJF

B) RR

C) FCFS

D) priority algorithms

Feedback: 5.3.1

Difficulty: Medium

11. I/O-bound program typically has many short ______ and a CPU-bound program might have a few long __________.

A) I/O burst, CPU burst

B) I/O burst, I/O burst

C) CPU burst, CPU burst

D) CPU burst, I/O burst

Section: 5.3.1

Difficulty: Easy

12. The ______ occurs in first-come-first-served scheduling when a process with a long CPU burst occupies the CPU.

A) dispatch latency

B) waiting time

C) convoy effect

D) system-contention scope

Feedback: 5.3.1

Difficulty: Medium

13. Which of the following scheduling algorithms gives the minimum average waiting time for a given set of processes?

A) SJF

B) FCFS

C) RR

D) Multilevel queue

Section: 5.3.2

Difficulty: Easy

14. Shortest-remaining-time-first scheduling is the preemptive version of __________?

A) SJF

B) FCFS

C) RR

D) Multilevel queue

Section: 5.3.2

Difficulty: Easy

15. Which of the following scheduling algorithms gives the minimum average response time?

A) SJF

B) FCFS

C) RR

D) Multilevel queue

Section: 5.3.3

Difficulty: Easy

16. A significant problem with priority scheduling algorithms is _____.

A) complexity

B) starvation

C) determining the length of the next CPU burst

D) determining the length of the time quantum

Feedback: 5.3.3

Difficulty: Medium

17. If the time quantum get too large, RR scheduling degenerates to __________?

A) SJF

B) FCFS

C) Shortest-remaining-time-first

D) Multilevel queue

Section: 5.3.3

Difficulty: Medium

18. Which of the following can be a solution to the problem of indefinite blockage of low-priority processes?

A) Aging

B) Starvation

C) Multilevel queue

D) All of the above

Section: 5.3.4

Difficulty: Easy

19. Which of the following processes usually have highest priority?

A) real-time processes

B) system processes

C) interactive processes

D) batch processes

Section: 5.3.5

Difficulty: Easy

20. Which of the following is allowed on Linux and Mac OS X systems?

A) only PTHREAD_SCOPE_PROCESS

B) only PTHREAD_SCOPE_SYSTEM

C) Both PTHREAD_SCOPE_PROCESS and PTHREAD_SCOPE_SYSTEM

D) none of the above

Section: 5.4.2

Difficulty: Easy

21. Which of the following system architectures involves multiprocessor scheduling?

A) multicore CPUs

B) multithreaded cores

C) NUMA systems

D) heterogeneous multiprocessing

E) all of the above

Section: 5.5

Difficulty: Easy

22. Which of the following is preemptive?

A) rate-monotonic scheduling

B) earliest-deadline-first scheduling

C) both of the above

D) none of the above

Section: 5.6.3 and 5.6.4

Difficulty: Medium

23. Which of the following POSIX API sets the scheduling policy?

A) pthread_attr_getsched_policy

B) pthread_attr_setsched_policy

C) pthread_attr_getscope

D) pthread_attr_setscope

Section: 5.6.6

Difficulty: Easy

24. The Linux CFS scheduler identifies _____________ as the interval of time during which every runnable task should run at least once.

A) virtual run time

B) targeted latency

C) nice value

D) load balancing

Feedback: 5.7.1

Difficulty: Medium

25. What is the numeric priority of a Windows thread in the NORMAL_PRIORITY_CLASS with HIGHEST relative priority?

A) 24

B) 10

C) 8

D) 13

Feedback: 5.7.2

Difficulty: Easy

26. What is the numeric priority of a Windows thread in the BELOW_NORMAL_PRIORITY_CLASS with NORMAL relative priority?

A) 6

B) 7

C) 5

D) 8

Feedback: 5.7.2

Difficulty: Easy

27. In Solaris, if an interactive thread with priority 25 is waiting for I/O, what is its priority recalculated to when it is eligible to run again?

A) 15

B) 120

C) 52

D) It remains at 25

Feedback: 5.7.3

Difficulty: Easy

28. In Solaris, what is the time quantum (in milliseconds) of an interactive thread with priority 35?

A) 25

B) 54

C) 80

D) 35

Section: 5.7.3

Difficulty: Easy

29. The default scheduling class for a process in Solaris is ____.

A) time sharing

B) system

C) interactive

D) real-time

Feedback: 5.7.3

Difficulty: Easy

Essay Questions

1. Explain the concept of a CPU–I/O burst cycle.

Feedback: 5.1.1

Difficulty: Medium

2. What role does the dispatcher play in CPU scheduling?

Feedback: 5.1.4

Difficulty: Medium

3. Explain the difference between response time and turnaround time. These times are both used to measure the effectiveness of scheduling schemes.

Feedback: 5.2

Difficulty: Medium

4. Explain the process of starvation and how aging can be used to prevent it.

a long enough period of time.

Feedback: 5.3.3

Difficulty: Difficult

5. What effect does the size of the time quantum have on the performance of an RR algorithm?

Feedback: 5.3.4

Difficulty: Medium

6. Explain the fundamental difference between asymmetric and symmetric multiprocessing.

Feedback: 5.5.1

Difficulty: Medium

7. Describe two general approaches to load balancing.

Feedback: 5.5.3

Difficulty: Medium

8. Distinguish between coarse-grained and fine-grained multithreading.

Feedback: 5.5.4

Difficulty: Medium

9. What are the two types of latency that affect the performance of real-time systems?

Section: 5.6.1

Difficulty: Medium

10. What are the advantages of the EDF scheduling algorithm over the rate-monotonic scheduling algorithm?

Section: 5.6.4

Difficulty: Medium

11. In Windows, how does the dispatcher determine the order of thread execution?

Feedback: 5.7.2

Difficulty: Difficult

12. What is deterministic modeling and when is it useful in evaluating an algorithm?

Feedback: 5.8.1

Difficulty: Medium

True/False Questions

1. In RR scheduling, the time quantum should be small with respect to the context-switch time.

Feedback: 5.3.4

Difficulty: Medium

2. Round-robin (RR) scheduling degenerates to first-come-first-served (FCFS) scheduling if the time quantum is too long.

Feedback: 5.3.4

Difficulty: Easy

3. The most complex scheduling algorithm is the multilevel feedback-queue algorithm.

Feedback: 5.3.6

Difficulty: Medium

4. Systems using a one-to-one model (such as Windows, Solaris , and Linux) schedule threads using process-contention scope (PCS).

Feedback: 5.4.1

Difficulty: Easy

5. Load balancing is typically only necessary on systems with a common run queue.

Feedback: 5.5.3

Difficulty: Medium

6. Load balancing algorithms have no impact on the benefits of processor affinity.

Feedback: 5.5.3

Difficulty: Medium

7. SMP systems that use multicore processors typically run faster than SMP systems that place each processor on separate cores.

Feedback: 5.5.4

Difficulty: Easy

8. A multicore system allows two (or more) threads that are in compute cycles to execute at the same time.

Feedback: 5.5.4

Difficulty: Easy

9. Providing a preemptive, priority-based scheduler guarantees hard real-time functionality.

Section: 5.6

Difficulty: Difficult

10. In hard real-time systems, interrupt latency must be bounded.

Section: 5.6.1

Difficulty: Medium

11. In Pthread real-time scheduling, the SCHED_FIFO class provides time slicing among threads of equal priority.

Section: 5.6.6

Difficulty: Medium

12. Solaris and Windows assign higher-priority threads/tasks longer time quantums and lower-priority tasks shorter time quantums.

Feedback: 5.7

Difficulty: Medium

13. In the Linux CFS scheduler, the task with smallest value of vruntime is considered to have the highest priority.

Section: 5.7.1

Difficulty: Medium

14. The length of a time quantum assigned by the Linux CFS scheduler is dependent upon the relative priority of a task.

Section: 5.7.1

Difficulty: Medium

15. The Completely Fair Scheduler (CFS) is the default scheduler for Linux systems.

Section: 5.7.1

Difficulty: Medium

16. Windows 7 User-mode scheduling (UMS) allows applications to create and manage thread independently of the kernel

Feedback: 5.7.2

Difficulty: Medium

17. A Solaris interactive thread with priority 15 has a higher relative priority than an interactive thread with priority 20

Feedback: 5.7.3

Difficulty: Easy

18. A Solaris interactive thread with a time quantum of 80 has a higher priority than an interactive thread with a time quantum of 120.

Feedback: 5.7.3

Difficulty: Easy