Download MIDTERM #1 WITH SOLUTIONS - School of Computer Science

MIDTERM EXAMINATION #1
OPERATING SYSTEM CONCEPTS
03-60-330-01
Winter 2010
UNIVERSITY OF WINDSOR
SCHOOL OF COMPUTER SCIENCE
PLEASE READ CAREFULLY BEFORE YOU START
1. This is a CLOSED book test; no notes, textbooks, calculators or computer aids are allowed.
2. PRINT your name legibly and clearly with your Student ID in the spaces indicated on the
Scantron sheet.
3. You will be asked to sign your name once before leaving the exam room (sign-out). By doing so
you state agreement to the terms below
I agree to the above terms and will neither receive nor give
unauthorized help on this exam.
4. All questions are multiple choice. Circle the single response which best answers each question.
5. Place all responses on the approved Scantron marking sheet using PENCIL.
6. You are not allowed to give or receive unauthorized help with your test. Any misconduct, as
outlined by the Senate bylaw 31 article I, will be reported accordingly.
7. You have 75 minutes to complete this test.
8. You may keep this question paper following the examination. A photocopy of your Scantron
sheet will be returned to you.
9. The maximum mark is 64.
Good Luck!
ANSWER SHEET
Page 1
All questions are Multiple Choice or True/False. In each Multiple Choice question, 4 responses
are provided – you are to choose only one response which best answers the question. Use the
Scantron sheet provided to indicate your answers. Circle the letter A, B, C or D (one only). For
True/False types of questions, circle either A or B. If an error is made you must carefully erase
the error and then fill in the circle you intend to choose.
USE PENCIL ONLY ON THE SCANTRON SHEET
1. A circular queue is the most appropriate data structure for ______ scheduling.
A) RR
B) FCFS
C) SJF
D) Multi-level
2. Turnaround time refers to the amount of time ______ .
A) that CPU utilization is minimized
B) needed to execute a particular process
C) a process has been waiting in the ready queue
D) it takes from when a request was submitted until the first action is produced
3. ____ is the amount of time a process has been waiting to enter the running state.
A) Wait time
B) Response time
C) Turnaround time
D) None of these responses are correct.
4. ____ is the amount of time it takes from when a request was submitted until the first
response is produced.
A) CPU utilization
B) Response time
C) Turnaround time
D) Throughput
5. ____ is the number of processes that are completed per time unit.
A) CPU utilization
B) Response time
C) Turnaround time
D) Throughput
Page 2
6. The major challenge in designing a layered operating system approach is ____.
A) making sure each layer is easily converted to modules
B) making sure that each layer hides certain data structures, hardware, and operations
from higher-level layers
C) appropriately defining the various layers
D) debugging a particular layer
7. In multiprocessor environments, two copies of the same data may reside in the local
cache of each CPU. Whenever one CPU alters the data, the cache of the other CPU must
receive an updated version of this data. This is called Cache _________ .
A) redundancy
B) integrity
C) coherency
D) normalization
8. Which of the following is considered a resource that may be allocated by an operating
system?
A) CPU
B) bus
C) file system
D) Instruction register
9. Two important design issues for cache memory are ____.
A) speed and volatility
B) size and replacement policy
C) power consumption and reusability
D) size and access privileges
10. Most often, application programs access system resources using ______ .
A) system calls
B) kernel threads
C) user threads
D) application program interfaces
11. CPU registers are often used to ________ .
A) pass parameters to the operating system
B) store values for reuse by other user programs
C) save memory for storing programs
D) All of the above responses are correct.
Page 3
12. The resource pyramid, with CPU registers and cache memories at one point of the
pyramid and tape drive storage at an opposite point, reflects which of the following
problems of computer design and operating system management?
A) Resource Allocation
B) Speed to Cost tradeoff
C) Volatility to Cost tradeoff
D) Both B and C responses are correct.
13. Thread-specific data is data that ____.
A) is not associated with any process
B) has been modified by the thread but not yet updated to the parent process
C) is copied and not shared with the parent process
D) is generated by the thread independent of the thread's process
14. The Producer-Consumer problem is related to _________ .
A) the allocation of resources to process states
B) the scheduling of process states
C) the handling of process control blocks
D) All of these responses are correct.
15. Which of the following is an operating system?
A) Linux
B) Solaris
C) Windows Vista
D) All of these responses are correct.
16. Which of the following is an example of a systems program?
A) command interpreter
B) Web browser
C) text formatter
D) database system
17. If a program terminates abnormally, a dump of memory may be examined by a ____ to
determine the cause of the problem.
A) module
B) debugger
C) shell
D) control card
Page 4
18. In RR scheduling, the time quantum should be _________ the context-switch time.
A) small with respect to
B) large with respect to
C) the same size as
D) irrelevant to
19. Context switching between processes is carried out by the
A) dispatcher
B) short term scheduler
C) interrupt handler
D) thread manager
20. An optimal job scheduling scheme is
A) RR
B) FCFS
C) SJF
D) Priority
21. A microkernel is a kernel ____.
A) that is stripped of all essential components
B) that is compressed before loading in order to reduce its resident memory size
C) that is compiled to produce the smallest size possible when stored to disk
D) containing many components that are optimized to reduce resident memory size
22. Which of the following pieces of information is least useful to the SYSGEN program of
an operating system?
A) the CPU being used
B) amount of memory available
C) what applications to install
D) operating-system options such as buffer sizes or CPU scheduling algorithms
23. A ____ circuit can be used to prevent a user program from never returning control to the
operating system.
A) portal
B) program counter
C) firewall
D) timer
Page 5
24. Bootstrap programs must be provided using ________ .
A) volatile memory
B) erasable-programmable memory
C) non-volatile ROM devices
D) special magnetic disk tracks
25. Long-term scheduling is performed _________ .
A) typically on submitted jobs
B) when processes must be moved from ready to waiting state
C) on processes in the ready queue
D) None of the above responses is correct.
26. Which of the following is true of multilevel queue scheduling?
A) Processes can move between queues.
B) Each queue has its own scheduling algorithm.
C) A queue cannot have absolute priority over lower-priority queues.
D) It is the most general CPU-scheduling algorithm.
27. In scheduling, the term Aging involves ___________ .
A) higher priority processes preventing low-priority processes from ever getting the
CPU.
B) gradually increasing the priority of a process so that a process will eventually
execute.
C) processes that are ready to run but stuck waiting indefinitely for the CPU.
D) processes being stuck in ready queues so long that they die.
28. Medium-term scheduling is performed _________ .
A) typically on submitted jobs
B) when processes must be moved from waiting to ready state
C) on processes in the ready queue
D) None of the above are correct.
29. An I/O-bound process _________ .
A) spends equal time seeking I/O operations and doing computational work
B) spends more of its time doing computational work than seeking I/O operations
C) spends more of its time seeking I/O operations than doing computational work
D) spends less of its time seeking I/O operations than doing computational work
Page 6
30. Processes are capable of _______ .
A) executing concurrently
B) performing data transfer operations
C) performing logic
D) All of the above responses are correct
31. ____ scheduling is approximated by predicting the next CPU burst with an exponential
average of the measured lengths of previous CPU bursts.
A) Multilevel queue
B) RR
C) FCFS
D) SJF
32. The ____ of a process contains temporary data such as function parameters, return
addresses, and local variables.
A) text section
B) data section
C) program counter
D) stack
33. The following are valid process states, including extensions to the 5-state basic model.
A) Next, Running, Halting
B) Terminating, Waiting, Threshing
C) Running, Blocked, Waiting
D) None of these responses is correct
34. A CPU-bound process _________ .
A) infrequently requests I/O operations and spends more of its time performing
computational work
B) frequently requests I/O operations and spends more of its time performing
computational work
C) infrequently requests I/O operations and spends less of its time performing
computational work
D) frequently requests I/O operations and spends less of its time performing
computational work
Page 7
35. A process control block ____.
A) includes information on the process's state
B) stores the address of the next instruction to be processed by a different process
C) determines which process is to be executed next
D) is an example of a process queue
36. The lowest cost secondary storage device is ____.
A) random access memory
B) DVD ROM
C) tape drive
D) magnetic disk
37. Which of the following is a property of peer-to-peer systems?
A) Clients and servers are not distinguished from one another.
B) Separate machines act as either the client of the server but not both.
C) They do not offer any advantages over traditional client-server systems.
D) They suffer from the server acting as the bottleneck in performance.
38. A message passing model is ____.
A) easier to implement than a shared memory model for inter-computer
communication
B) is faster than the shared memory model
C) a network protocol and does not apply to operating systems
D) is only useful for small simple operating systems
39. An advantage to using a higher-level language to implement an operating system is
___________ .
A) the system can be understood by all users
B) modern computer science students do not learn machine language programming
C) an operating system is far easier to port to some other hardware if it is written in a
higher-level language
D) Both A and B are correct responses
40. For a single-processor system __________ .
A) processes spend long times waiting to execute
B) there will never be more than one running process
C) input-output always causes CPU slowdown
D) process scheduling is always optimal
Page 8
41. In the context of operating systems, the term Policy ____.
A) determines how to do something
B) determines what will be done
C) is not likely to change across places
D) is not likely to change over time
42. The most volatile form of computer storage is ____.
A) random access memory
B) CPU registers
C) tape drive
D) magnetic disk
43. The most responsive, or fastest, category of computer storage is ____.
A) random access memory
B) CPU registers
C) DVD/CD-ROM
D) cache memory
44. A thread control block _______ .
A) is managed by the parent process
B) contains the same information as the process control block
C) has the identical structure as the process control block
D) does not include information about the parent process resource allocation
45. The list of processes waiting for a particular I/O device is called a(n) ____.
A) standby queue
B) device queue
C) wait queue
D) interrupt queue
46. In a(n) ____ temporary queue, the sender must always block until the recipient receives
the message.
A) zero capacity
B) variable capacity
C) bounded capacity
D) unbounded capacity
Page 9
47. Marshalling refers to ________ .
A) packaging parameters in a form suitable for network transmission
B) initiating a remote procedure call to a networked computer
C) leading the packet train in TCP/IP messaging
D) ordering processes in state queues
48. A program file is _________ .
A) another name for a process
B) an active entity
C) a passive entity
D) All of the above responses are correct.
49. When a child process is created, which of the following is a possibility in terms of the
execution or address space of the child process?
A) The child process runs concurrently with the parent.
B) The child process may outlive the parent.
C) The child may acquire more resources than the parent.
D) None of the above responses is correct.
50. The ____ scheduling algorithm is designed especially for time-sharing systems.
A) SJF
B) FCFS
C) RR
D) Multilevel queue
51. In a virtual machine, each program believes that it has ____.
A) multiple processors
B) its own memory
C) another "virtual" computer to assist in its operations
D) more memory than is physically available on the machine
52. The two modes of operation of an operating system are called ___________ .
A) process and kernel
B) ready and running
C) interrupt and system
D) kernel and user
Page 10
53. An operating system may be viewed as a resource allocator of such things as CPU time,
memory space, file-storage space, I/O devices, and so on, due to the requirement that
_________ .
A) such things need to allocated to be useful for operating systems to work
B) conflicts of resource usage must not be permitted to happen
C) computer users must be satisfied that resources are available on request
D) resources be used efficiently by users
54. Which of the following scheduling algorithms must be nonpreemptive?
A) SJF
B) RR
C) FCFS
D) priority algorithms
55. When a process is accessing its stack space, it exists in the _________ .
A) Running state
B) Waiting state
C) Terminating state
D) Ready state
56. A process control block should contain __________ .
A) the process ID
B) locations to store register values
C) a list of all open files
D) All of these responses are correct
57. Pthreads refers to ____.
A) the POSIX standard.
B) an implementation for thread behavior.
C) an algorithm for thread behavior.
D) an API for process creation and synchronization.
58. When a process performs I/O, its PCB is moved to the ________ .
A) Ready queue
B) Wait queue
C) Terminate queue
D) Running queue
Page 11
59. Assume the following processes, each with their arrival time and burst time.
Process
P1
P2
P3
P4
P5
Arrival Time
0.0
2.0
4.0
5.0
6.0
Burst Time
7
2
1
4
3
For SJF Non-Preemptive job scheduling, the average waiting time is
A) 4.0
B) 4.2
C) 4.4
D) 4.6
60. Assume the following processes, each with their arrival time and burst time.
Process
P1
P2
P3
P4
P5
Arrival Time
0.0
2.0
4.0
5.0
6.0
Burst Time
7
2
1
4
3
For FCFS job scheduling, the average waiting time is _______ .
A) 4.6
B) 4.0
C) 3.75
D) 4.2
Page 12
61. Assume the following processes, each with their arrival time and burst time.
Process
P1
P2
P3
P4
P5
Arrival Time
0.0
2.0
4.0
5.0
6.0
Burst Time
7
2
1
4
3
For SJF Preemptive job scheduling (where a newly arriving process is included in the
selection of the next running process), the average waiting time is
A) 4.4
B) 4.0
C) 3.6
D) 2.6
62. Assume the following processes, each with their arrival time and burst time.
Process
P1
P2
P3
P4
P5
Arrival Time
0.0
2.0
4.0
5.0
6.0
Burst Time
7
2
1
4
3
For Round Robin (RR) job scheduling with time quantum equal to 1 (and where a newly
arriving process is selected as the next running process), the average waiting time is
A) 6.0
B) 4.0
C) 5.2
D) 4.8
Page 13
The remaining questions 63 and 64 all refer to the process state diagram below.
NEW
TERMINATED
READY
RUNNING
WAITING
63. The state transition from RUNNING to READY happens when a process _____ .
A) is interrupted
B) performs an I/O or event handling
C) completes an I/O or event handling
D) is dispatched by the scheduler
64. The state transition from WAITING to READY happens when a process _____ .
A) is interrupted
B) performs an I/O or event handling
C) completes an I/O or event handling
D) is dispatched by the scheduler
** END OF EXAMINATION QUESTIONS **
Page 14