CSC 415 Operating System Principles Unit 08

In Solaris, if an interactive thread with priority 15 uses its entire time quantum, what is its priority recalculated to? A) 51 B) 5 C) 160 D) It remains at 15

B) 5

The rate of a periodic task in a hard real-time system is ____, where p is a period and t is the processing time. Select one: a. p/t b. 1/t c. 1/p d. pt

c. 1/p

Which of the following scheduling algorithm may suffer from convoy effect? Select one: a. SJF b. Multilevel queue c. FCFS d. RR

c. FCFS

What is the numeric priority of a Windows thread in the HIGH_PRIORITY_CLASS with ABOVE_NORMAL relative priority? A) 24 B) 10 C) 8 D) 14

D) 14

In preemptive scheduling, the sections of code affected by interrupts must be guarded from simultaneous use. Select one: True False

True

In Solaris, what is the time quantum (in milliseconds) of an interactive thread with priority 35? Select one: a. 80 b. 35 c. 25 d. 54

a. 80

Which of the following can be a solution to the problem of indefinite blockage of low-priority processes? Select one: a. Aging b. Multilevel queue c. All of the other answers d. Starvation

a. Aging

Which of the following is true of the rate-monotonic scheduling algorithm? Select one: a. CPU utilization is bounded when using this algorithm. b. The task with the shortest period will have the lowest priority. c. Fine-It uses a dynamic priority policy. d. It is non-preemptive.

a. CPU utilization is bounded when using this algorithm.

Which of the following is true of multilevel queue scheduling? Select one: a. Each queue has its own scheduling algorithm. b. Processes can move between queues. c. It is the most general CPU-scheduling algorithm. d. A queue cannot have absolute priority over lower-priority queues.

a. Each queue has its own scheduling algorithm.

Load balancing is typically only necessary on systems with a common run queue. Select one: a. False b. True

a. False

Providing a preemptive, priority-based scheduler guarantees hard real-time functionality. Select one: a. False b. True

a. False

The length of a time quantum assigned by the Linux CFS scheduler is dependent upon the relative priority of a task. Select one: a. False b. True

a. False

The ____ scheduling algorithm is designed especially for time-sharing systems. Select one: a. RR b. FCFS c. Multilevel queue d. SJF

a. RR

Shortest-remaining-time-first scheduling is the preemptive version of __________? Select one: a. SJF b. RR c. FCFS d. Multilevel queue

a. SJF

____ scheduling is approximated by predicting the next CPU burst with an exponential average of the measured lengths of previous CPU bursts. Select one: a. SJF b. FCFS c.Multilevel queue d. RR

a. SJF

A multicore system allows two (or more) threads that are in compute cycles to execute at the same time. Select one: a. True b. False

a. True

Round-robin (RR) scheduling degenerates to first-come-first-served (FCFS) scheduling if the time quantum is too long. Select one: a. True b. False

a. True

Windows 7 User-mode scheduling (UMS) allows applications to create and manage thread independently of the kernel Select one: a. True b. False

a. True

Which of the following is true of earliest-deadline-first (EDF) scheduling algorithm? Select one: a. When a process becomes runnable, it must announce its deadline requirements to the system. b. Deadlines are assigned as following: the earlier the deadline, the lower the priority; the later the deadline, the higher the priority. c. It assigns priorities statically according to deadline. d. Priorities are fixed; that is, they cannot be adjusted when a new process starts running.

a. When a process becomes runnable, it must announce its deadline requirements to the system.

Which of the following is preemptive? Select one: a. both of the above b. none of the other answers c. rate-monotonic scheduling d. earliest-deadline-first scheduling

a. both of the above

Windows gives a 3x priority boost to? Select one: a. foreground applications b. interrupt routines c. system functions d. background applications

a. foreground applications

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? Select one: a. save state into PCB0, and restore state from PCB1 b. P0 executing c. all of the other answers d. P1 executing

a. save state into PCB0, and restore state from PCB1

For interactive systems, it is more important to minimize ________. Select one: a. the variance in response time b. the average response time c. the average turnaround time d. the waiting time

a. the variance in response time

In RR scheduling, the time quantum should be small with respect to the context-switch time. Select one: a. True b. False

b. False

Solaris and Windows assign higher-priority threads/tasks longer time quantums and lower-priority tasks shorter time quantums. Select one: a. True b. False

b. False

____ allows a thread to run on only one processor. Select one: a. Load balancing b. Processor affinity c. NUMA d. Processor Set

b. Processor affinity

Shortest-remaining-time-first scheduling is the preemptive version of __________? Select one: a. RR b. SJF c. FCFS d. Multilevel queue

b. SJF

Which of the following statements are false with regards to the Linux CFS scheduler? Select one: a. Lower numeric values indicate higher relative priorities. b. There is a single, system-wide value of vruntime. c. The scheduler doesn't directly assign priorities. d. Each task is assigned a proportion of CPU processing time.

b. There is a single, system-wide value of vruntime.

A Solaris interactive thread with a time quantum of 80 has a higher priority than an interactive thread with a time quantum of 120. Select one: a. False b. True

b. True

In hard real-time systems, interrupt latency must be bounded. Select one: a. False b. True

b. True

In the Linux CFS scheduler, the task with smallest value of vruntime is considered to have the highest priority. Select one: a. False b. True

b. True

The Completely Fair Scheduler (CFS) is the default scheduler for Linux systems. Select one: a. False b. True

b. True

The ready queue can be implemented as a _______________. Select one: a. unordered linked list b. all of the other answers c. priority queue d. tree e. FIFO queue

b. all of the other answers

Which of the following is allowed on Linux and Mac OS X systems? Select one: a. Both PTHREAD_SCOPE_PROCESS and PTHREAD_SCOPE_SYSTEM b. only PTHREAD_SCOPE_SYSTEM c. only PTHREAD_SCOPE_PROCESS d. none of the other answers

b. only PTHREAD_SCOPE_SYSTEM

Which of the following POSIX API sets the scheduling policy? Select one: a. pthread_attr_getscope b. pthread_attr_setsched_policy c. pthread_attr_getsched_policy d. pthread_attr_setscope

b. pthread_attr_setsched_policy

Which of the following circumstances can cooperative scheduling take place? Select one: a. none of the other answers b. when a process switches from the running state to the waiting state c. when a process switches from the waiting state to the ready state d. when a process switches from the running state to the ready state

b. when a process switches from the running state to the waiting state

Which of the following is true of cooperative scheduling? Select one: a. It requires a timer. b. It incurs a cost associated with access to shared data. c. A process keeps the CPU until it releases the CPU either by terminating or by switching to the waiting state. d. A process switches from the running state to the ready state when an interrupt occurs.

c. A process keeps the CPU until it releases the CPU either by terminating or by switching to the waiting state.

I/O-bound program typically has many short ______ and a CPU-bound program might have a few long __________. Select one: a. I/O burst, I/O burst b. CPU burst, I/O burst c. CPU burst, CPU burst d. I/O burst, CPU burst

c. CPU burst, CPU burst

If the time quantum gets too large, RR scheduling degenerates to __________? Select one: a. Shortest-remaining-time-first b. Multilevel queue c. FCFS d. SJF

c. FCFS

Which of the following scheduling algorithms gives the minimum average response time? Select one: a. FCFS b. SJF c. RR d. Multilevel queue

c. RR

Which of the following criteria is more important from the point of view of a particular process? Select one: a. Response time b. CPU utilization c. Turnaround time d. Throughput

c. Turnaround time

In Little's formula, λ, represents the ____. Select one: a. average queue length b. average waiting time in the queue c. average arrival rate for new processes in the queue d. average CPU utilization

c. average arrival rate for new processes in the queue

The ______ occurs in first-come-first-served scheduling when a process with a long CPU burst occupies the CPU. Select one: a. dispatch latency b. system-contention scope c. convoy effect d. waiting time

c. convoy effect

Which of the following processes usually have highest priority? Select one: a. system processes b. interactive processes c. real-time processes d. batch processes

c. real-time processes

A significant problem with priority scheduling algorithms is _____. Select one: a. determining the length of the time quantum b. complexity c. starvation d. determining the length of the next CPU burst

c. starvation

The default scheduling class for a process in Solaris is ____. Select one: a. system b. real-time c. time sharing d. interactive

c. time sharing

Which of the following circumstances can preemptive scheduling take place? Select one: a. when a process terminates b. when a process switches from the running state to the waiting state c. when a process switches from the waiting state to the ready state d. none of the other answers

c. when a process switches from the waiting state to the ready state

Which scheduling criteria is the most important? Select one: a. Throughput b. Waiting Time c. Response Time d. Depends on the system needs e. Turnaround Time f. CPU Utilization

d. Depends on the system needs

Which of the following scheduling algorithms must be nonpreemptive? Select one: a. RR b. priority algorithms c. SJF d. FCFS

d. FCFS

Which of the following criteria is more important for an interactive system? Select one: a. CPU utilization b. Turnaround time c. Throughput d. Response time

d. Response time

Which of the following scheduling algorithms gives the minimum average waiting time for a given set of processes? Select one: a. FCFS b. Multilevel queue c. RR d. SJF

d. SJF

____ involves the decision of which kernel thread to schedule onto which CPU. Select one: a. Dispatcher b. Process-contention scope c. Round-robin scheduling d. System-contention scope

d. System-contention scope

____ is the number of processes that are completed per time unit. Select one: a. Turnaround Time b. CPU utilization c. Response Time d. Throughput

d. Throughput

With ____ a thread executes on a processor until a long-latency event (i.e. a memory stall) occurs. Select one: a. virtualization b. fine-grained multithreading c. multicore processors d. coarse-grained multithreading

d. coarse-grained multithreading

The two general approaches to load balancing are ____ and ____. Select one: a. soft real-time, hard real-time b. coarse grained, fine grained c. soft affinity, hard affinity d. push migration, pull migration

d. push migration, pull migration

Which of the following items does not belong to the function of a dispatcher? Select one: a. switching to user mode b. switching context from one process to another c. jumping to the proper location in the user program to resume that program d. selecting a process among the available ones in the ready queue

d. selecting a process among the available ones in the ready queue

The Linux CFS scheduler identifies _____________ as the interval of time during which every runnable task should run at least once. Select one: a. load balancing b. nice value c. virtual run time d. targeted latency

d. targeted latency

Which of the following system architectures involves multiprocessor scheduling? Select one: a. NUMA systems b. heterogeneous multiprocessing c. multicore CPUs d. multithreaded cores e. all of the other answers

e. all of the other answers

Which algorithm evaluation method yields the best results? Select one: a. Deterministic Evaluation b. Implement new scheduler and test in real systems c. Simulations d. Queueing Models

not b