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Unit 2: CPU Scheduling - Practice Quiz

CSE316 — Operating Systems 50 Questions
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1 Which component of the Operating System is responsible for selecting a process from the ready queue and allocating the CPU to it?

A. Job Scheduler
B. Interrupt Handler
C. CPU Scheduler
D. Dispatcher

2 The module that gives control of the CPU to the process selected by the short-term scheduler is known as:

A. Scheduler
B. Allocator
C. Interrupt Service Routine
D. Dispatcher

3 What is 'Dispatch Latency'?

A. The time it takes for the dispatcher to stop one process and start another
B. The time it takes for a process to complete execution
C. The time a process waits in the ready queue
D. The time taken by the CPU to execute an instruction

4 In which of the following situations is CPU scheduling decision mandatory (non-preemptive)?

A. When a process switches from waiting to ready state
B. When a process terminates
C. When a process switches from running to ready state
D. When a process switches from ready to running state

5 Which scheduling algorithm results in the 'Convoy Effect'?

A. Round Robin
B. Shortest Job First
C. Priority Scheduling
D. First-Come, First-Served

6 What is the primary objective of the Shortest Job First (SJF) scheduling algorithm?

A. To minimize average waiting time
B. To ensure fairness
C. To minimize response time
D. To maximize throughput

7 Preemptive Shortest Job First scheduling is also known as:

A. Shortest Remaining Time First
B. Round Robin
C. Multilevel Queue Scheduling
D. Preemptive Priority Scheduling

8 In Round Robin scheduling, if the time quantum is extremely large, the algorithm degenerates into which scheduling policy?

A. Multilevel Feedback Queue
B. Shortest Job First
C. First-Come, First-Served
D. Priority Scheduling

9 What is the major drawback of Priority Scheduling?

A. Starvation
B. High overhead
C. Low throughput
D. Deadlock

10 Which technique is used to solve the problem of starvation in Priority Scheduling?

A. Aging
B. Context Switching
C. Swapping
D. Paging

11 Which scheduling criteria refers to the number of processes that complete their execution per time unit?

A. Throughput
B. Turnaround time
C. CPU utilization
D. Response time

12 Turnaround time is defined as:

A. The total time the CPU is busy
B. The time a process spends waiting in the ready queue
C. The time from submission to the first response
D. The time from submission of a process to the time of completion

13 Which scheduling algorithm is designed specifically for time-sharing systems?

A. Round Robin
B. First-Come, First-Served
C. Non-preemptive Priority
D. Shortest Job First

14 In Multilevel Feedback Queue scheduling, a process can:

A. Choose its own priority
B. Only stay in one queue
C. Never be preempted
D. Move between queues

15 If a process is I/O bound, in a Multilevel Feedback Queue, it should ideally be placed in:

A. A lower priority queue with a long time quantum
B. A blocked queue permanently
C. The last queue in the system
D. A higher priority queue with a short time quantum

16 What is 'Process Affinity' (or Processor Affinity) in multiprocessor scheduling?

A. A process creates a child process
B. Two processes share the same memory
C. Processes communicate via signals
D. A process prefers to run on the same processor it ran on previously

17 Which of the following is NOT a characteristic of a Hard Real-Time System?

A. Missing a deadline is a total system failure
B. Guaranteed quality of service
C. Deadlines are optional if system is busy
D. Critical tasks must complete on time

18 Rate Monotonic Scheduling assigns priorities to tasks based on their:

A. Deadline
B. CPU Burst time
C. Period (frequency)
D. Arrival time

19 Earliest Deadline First (EDF) scheduling assigns priorities:

A. Statically based on period
B. Dynamically based on closeness to deadline
C. Based on shortest burst
D. Randomly

20 In Thread Scheduling, the distinction between PCS (Process-Contention Scope) and SCS (System-Contention Scope) relies on:

A. The programming language used
B. The level at which threads compete for CPU time
C. The amount of memory allocated
D. The size of the thread

21 The formula for calculating Waiting Time for a specific process is:

A. Response Time + Burst Time
B. Burst Time + Arrival Time
C. Completion Time - Arrival Time
D. Turnaround Time - Burst Time

22 Which scheduling algorithm is most difficult to implement because it requires predicting the future?

A. FCFS
B. Multilevel Queue
C. SJF
D. Round Robin

23 In asymmetric multiprocessing:

A. No processor controls another
B. Each processor has its own ready queue only
C. One processor (master) controls the system, others look to it or have predefined tasks
D. All processors are peers

24 Load balancing in multiprocessor systems involves:

A. Disabling interrupts
B. Push migration and Pull migration
C. Reducing the number of processors
D. Increasing the time quantum

25 Which of the following is a criterion for 'Response Time'?

A. Time to output the first character
B. Time spent in ready queue
C. Time from submission to first response produced
D. Time to finish the whole job

26 Under preemptive scheduling, when can the CPU be taken away from a process?

A. Only when the process requests I/O
B. Only when the process terminates
C. When an interrupt occurs or a higher priority process arrives
D. Never

27 What determines the efficiency of the Round Robin algorithm?

A. The number of processes
B. The size of the time quantum
C. The I/O speed
D. The memory size

28 In the context of scheduling, what is 'Little's Law' used for?

A. Estimating the next CPU burst
B. Assigning priorities
C. Determining average queue length based on arrival rate and average wait time
D. Detecting deadlocks

29 Which method is commonly used to predict the next CPU burst duration for SJF?

A. Fixed constant value
B. Exponential averaging of previous bursts
C. Random guessing
D. User input

30 What is 'Soft Affinity'?

A. The process runs only on the master processor
B. The OS attempts to keep the process on the same processor but doesn't guarantee it
C. The process runs on any processor randomly
D. The OS guarantees the process runs on the same processor

31 A system where the ready queue is partitioned into separate queues (e.g., foreground and background) with different scheduling algorithms is called:

A. Round Robin
B. SJF
C. FCFS
D. Multilevel Queue Scheduling

32 Which priority applies in Windows scheduling when a thread is running in the kernel?

A. Idle priority
B. Variable priority
C. Real-time priority
D. GUI priority

33 Pthread scheduling API allows specifying the scope of contention. What does PTHREAD_SCOPE_SYSTEM mean?

A. The thread competes only within the process
B. The thread cannot be preempted
C. The thread is a kernel thread only
D. The thread competes with all threads in the system for CPU

34 In a real-time system, 'Interrupt Latency' refers to:

A. Time waiting for the interrupt
B. Time from interrupt arrival to the start of the execution of the ISR
C. Time to execute the ISR
D. Time to return from the ISR

35 Which scheduling algorithm ensures that no process waits more than (n-1) x q time units, where n is the number of processes and q is the time quantum?

A. FCFS
B. Priority
C. Round Robin
D. SJF

36 Cooperative scheduling is another name for:

A. Non-preemptive scheduling
B. Multiprocessor scheduling
C. Thread scheduling
D. Preemptive scheduling

37 Typically, a long-term scheduler executes:

A. Only at system boot
B. When an interrupt occurs
C. Every few milliseconds
D. Much less frequently than the short-term scheduler

38 Which of the following is true about 'Admission Control' in Real-Time Scheduling?

A. It is used in FCFS
B. It ignores deadlines
C. It admits all processes regardless of load
D. It admits a process only if the system can guarantee its deadline

39 In calculating average waiting time, what is the arrival time usually assumed to be if not specified?

A. 1
B. Infinity
C. 10
D. 0

40 What is the main disadvantage of Multilevel Feedback Queue scheduling?

A. It causes immediate deadlock
B. It cannot handle I/O bound processes
C. It does not support interactive users
D. It is the most complex to implement and tune

41 What happens to the 'Context Switch' time?

A. It is useful processing time
B. It shortens the process execution
C. It is pure overhead
D. It is used for I/O

42 Conflict phase of dispatch latency typically involves:

A. Loading the new program from disk
B. Preemption of any process running in the kernel and release by low-priority process of resources
C. Waiting for user input
D. Formatting the hard drive

43 Which scheduling algorithm suffers from the problem of indefinite blocking?

A. Priority Scheduling
B. Rate Monotonic
C. Round Robin
D. FIFO

44 In SMP (Symmetric Multiprocessing), where can a process run?

A. Only on CPU 0
B. On the I/O processor only
C. On any available processor
D. On the GPU only

45 What is the 'Throughput' if 10 processes finish in 5 seconds?

A. 5 processes/second
B. 50 processes/second
C. 0.5 processes/second
D. 2 processes/second

46 Typically, 'Foreground' processes in a Multilevel Queue system use which algorithm?

A. FCFS
B. Round Robin
C. SJF
D. Random

47 Typically, 'Background' processes in a Multilevel Queue system use which algorithm?

A. Real-time
B. FCFS
C. Round Robin
D. Priority

48 Which type of thread scheduling allows the user-level thread library to schedule threads?

A. Hard Real-time
B. Round Robin
C. System-Contention Scope (SCS)
D. Process-Contention Scope (PCS)

49 If a process has a CPU burst of 10ms and the time quantum is 20ms, what happens?

A. The CPU idles for 10ms
B. The process runs for 10ms, terminates/yields, and the context switches
C. The process is forced to run for 20ms
D. An error occurs

50 Which concept describes the cycle of CPU execution and I/O wait?

A. Fetch-Decode-Execute Cycle
B. CPU-I/O Burst Cycle
C. Interrupt Cycle
D. Boot Cycle
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