Deck 5: Cpu Scheduling

Question 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

Answer 1

E

Question 2

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

Answer 2

B

Question 3

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

A) SJF
B) FCFS
C) Shortest-remaining-time-first
D) Multilevel queue

Answer 3

B

Question 4

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

Question 5

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

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

Question 6

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

Question 7

Which of the following scheduling algorithms must be nonpreemptive?

A) SJF
B) RR
C) FCFS
D) priority algorithms

Question 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

Question 9

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

Question 10

Which of the following processes usually have highest priority?

A) real-time processes
B) system processes
C) interactive processes
D) batch processes

Question 11

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

Question 12

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

A) SJF
B) FCFS
C) RR
D) Multilevel queue

Question 13

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

A) SJF
B) FCFS
C) RR
D) Multilevel queue

Question 14

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

Question 15

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

Question 16

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

Question 17

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

A) SJF
B) FCFS
C) RR
D) Multilevel queue

Question 18

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

Question 19

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

Question 20

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

Question 21

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

Question 22

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

Question 23

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

Question 24

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

Question 25

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

A) 25
B) 54
C) 80
D) 35

Question 26

What role does the dispatcher play in CPU scheduling?

Question 27

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

Question 28

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

Question 29

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

Question 30

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

Question 31

Describe two general approaches to load balancing.

Question 32

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

Question 33

Distinguish between coarse-grained and fine-grained multithreading.

Question 34

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

Question 35

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

Question 36

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

Question 37

Explain the fundamental difference between asymmetric and symmetric multiprocessing.

Question 38

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

Question 39

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

A) time sharing
B) system
C) interactive
D) real-time

Question 40

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

Question 41

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

Question 42

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

Question 43

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

Question 44

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

Question 45

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

Question 46

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

Question 47

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

Question 48

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

Question 49

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

Question 50

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

Question 51

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

Question 52

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

Question 53

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

Question 54

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

Question 55

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

Question 56

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

Question 57

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