Question 1

Describe the dining-philosophers problem and how it relates to operating systems.

Accepted Answer

The scenario involves five philosophers

Question 2

In the structure of the producer process shown in Figure 7.1, what would be a possible outcome if wait(empty) is replaced with signal(empty) and signal(full) is replaced with wait(full)?

Accepted Answer

A)  Producer will remain blocked after adding an item in the buffer. 
B)  Consumer will remain blocked after taking out an item from the buffer. 
C)  Producer and consumer may access the buffer at the same time. 
D)  All of the above. 
A)  Producer will remain blocked after adding an item in the buffer. 
B)  Consumer will remain blocked after taking out an item from the buffer. 
C)  Producer and consumer may access the buffer at the same time. 
D)  All of the above.

Question 3

A(n) ___________ is a sequence of read-write operations that are atomic.

Accepted Answer

A)  atomic integer 
B)  semaphore 
C)  memory transaction 
D)  mutex lock 
A)  atomic integer 
B)  semaphore 
C)  memory transaction 
D)  mutex lock

Question 4

A thread using POSIX condition variables, a thread

Accepted Answer

A)  must lock the associated mutex lock before calling pthread_cond_wait( ) and unlock it after calling pthread_cond_signal( ). 
B)  must lock the associated mutex lock before calling pthread_cond_wait( ), but doesn't need to unlock it after calling pthread_cond_signal( ). 
C)  doesn't need to lock the associated mutex lock before calling pthread_cond_wait( ), but must unlock it after calling pthread_cond_signal( ). 
D)  doesn't need to lock the associated mutex lock before calling pthread_cond_wait( ) and doesn't need to unlock it after calling pthread_cond_signal( ). 
A)  must lock the associated mutex lock before calling pthread_cond_wait( ) and unlock it after calling pthread_cond_signal( ). 
B)  must lock the associated mutex lock before calling pthread_cond_wait( ), but doesn't need to unlock it after calling pthread_cond_signal( ). 
C)  doesn't need to lock the associated mutex lock before calling pthread_cond_wait( ), but must unlock it after calling pthread_cond_signal( ). 
D)  doesn't need to lock the associated mutex lock before calling pthread_cond_wait( ) and doesn't need to unlock it after calling pthread_cond_signal( ).

Question 5

Dispatcher objects in Windows are used for synchronization outside the kernel.

Accepted Answer

A) True 
 B)False

Question 6

To lock the kernel on a single processor machine in Linux, kernel preemption is disabled.

Accepted Answer

A) True 
 B)False

Question 7

A key difference between Reentrant locks and JAVA monitor's synchronized statements is that

Accepted Answer

A)  there is a possibility of deadlock when using a monitor while deadlock cannot occur when using reentrant locks. 
B)  a reentrant lock favors granting the lock to the longest-waiting thread while there is no specification for the order in which threads in the wait set for an object lock. 
C)  multiple processes may own a reentrant lock at the same time while at most one process may execute inside a synchronized method at any time. 
D)  at most one process may own a reentrant lock, while multiple processes may execute inside a synchronized method at any time. 
A)  there is a possibility of deadlock when using a monitor while deadlock cannot occur when using reentrant locks. 
B)  a reentrant lock favors granting the lock to the longest-waiting thread while there is no specification for the order in which threads in the wait set for an object lock. 
C)  multiple processes may own a reentrant lock at the same time while at most one process may execute inside a synchronized method at any time. 
D)  at most one process may own a reentrant lock, while multiple processes may execute inside a synchronized method at any time.

Question 8

Explain how Linux manages race conditions on single-processor systems such as embedded devices.

Accepted Answer

On multiprocessor machines, Linux uses s

Question 9

POSIX unnamed semaphores can be shared either only by threads with in a single process, or between processes.

Accepted Answer

A) True 
 B)False

Question 10

In JAVA, calling a synchronized method always blocks the calling thread.

Accepted Answer

A) True 
 B)False

Question 11

Explain the difference between the first readers-writers problem and the second readers--writers problem.

Accepted Answer

The first readers-writers problem requir

Question 12

An advantage of using transactional memory is that

Accepted Answer

A)  the atomicity is guaranteed by the transactional memory system. 
B)  there is no possibility of deadlocks. 
C)  the transactional memory system can identify which statements in atomic blocks can be executed concurrently. 
D)  All of the above. 
A)  the atomicity is guaranteed by the transactional memory system. 
B)  there is no possibility of deadlocks. 
C)  the transactional memory system can identify which statements in atomic blocks can be executed concurrently. 
D)  All of the above.

Question 13

With reentrant locks, programming construct try and finally is used to ensure that unlock( ) is called even when an exception occurs in the critical section.

Accepted Answer

A) True 
 B)False

Question 14

Alternate approaches such as transactional memory or OpenMP are useful, because

Accepted Answer

A)  some race condition problems that cannot be solved using synchronization mechanisms such as mutex locks and semaphores can be solved using these alternate approaches. 
B)  these approaches scale much better than synchronization mechanisms such as mutex locks and semaphores as the number of threads increases. 
C)  developers do not need to identify race conditions when using these approaches. 
D)  All of the above. 
A)  some race condition problems that cannot be solved using synchronization mechanisms such as mutex locks and semaphores can be solved using these alternate approaches. 
B)  these approaches scale much better than synchronization mechanisms such as mutex locks and semaphores as the number of threads increases. 
C)  developers do not need to identify race conditions when using these approaches. 
D)  All of the above.

Question 15

A critical section object in the user mode needs kernel intervention to ensure mutual exclusion.

Accepted Answer

A) True 
 B)False

Question 16

Describe how a critical-section object functions.

Accepted Answer

A critical-section object can be acquire

Question 17

Explain what will happen if a process A locks the associated mutex before calling pthread cond wait( ), but another process B does not lock the associated mutex before call pthread_cond_signal( ).

Accepted Answer

In this case, there is a race

Question 18

Critical-section compiler directive in OpenMP is generally considered easier to use than standard mutex locks, because

Accepted Answer

A)  management of entry and exit code is managed by OpenMP library reducing the possibility of programming errors. 
B)  programmers don't need to worry about race conditions. 
C)  a thread cannot block inside a critical section. 
D)  deadlock cannot occur. 
A)  management of entry and exit code is managed by OpenMP library reducing the possibility of programming errors. 
B)  programmers don't need to worry about race conditions. 
C)  a thread cannot block inside a critical section. 
D)  deadlock cannot occur.

Question 19

Explain the role of the variable preempt_count in the Linux kernel.

Accepted Answer

Each task maintains a value preempt_coun

Question 20

In a single processor system running Windows, when the kernel accesses a global resource, it

Accepted Answer

A)  uses spinlocks. 
B)  masks all interrupts. 
C)  uses a dispatcher object. 
D)  atomic integers. 
A)  uses spinlocks. 
B)  masks all interrupts. 
C)  uses a dispatcher object. 
D)  atomic integers.

Describe the dining-philosophers problem and how it relates to operating systems.

In the structure of the producer process shown in Figure 7.1, what would be a possible outcome if wait(empty) is replaced with signal(empty) and signal(full) is replaced with wait(full)?

A(n) ___________ is a sequence of read-write operations that are atomic.

A thread using POSIX condition variables, a thread

Dispatcher objects in Windows are used for synchronization outside the kernel.

To lock the kernel on a single processor machine in Linux, kernel preemption is disabled.

A key difference between Reentrant locks and JAVA monitor's synchronized statements is that

Explain how Linux manages race conditions on single-processor systems such as embedded devices.

POSIX unnamed semaphores can be shared either only by threads with in a single process, or between processes.

In JAVA, calling a synchronized method always blocks the calling thread.

Explain the difference between the first readers-writers problem and the second readers--writers problem.

An advantage of using transactional memory is that

With reentrant locks, programming construct try and finally is used to ensure that unlock( ) is called even when an exception occurs in the critical section.

Alternate approaches such as transactional memory or OpenMP are useful, because

A critical section object in the user mode needs kernel intervention to ensure mutual exclusion.

Describe how a critical-section object functions.

Explain what will happen if a process A locks the associated mutex before calling pthread cond wait( ), but another process B does not lock the associated mutex before call pthread_cond_signal( ).

Critical-section compiler directive in OpenMP is generally considered easier to use than standard mutex locks, because

Explain the role of the variable preempt_count in the Linux kernel.

In a single processor system running Windows, when the kernel accesses a global resource, it

Introduction

Operating-System Structures

Processes

Threads Concurrency

Cpu Scheduling

Synchronization Tools

Deadlocks

Main Memory

Virtual Memory

Mass-Storage Structure

Io Systems

File-System Interface

File-System Implementation

File-System Internals

Security

Protection

Filters

Exam 7: Synchronization Examples

Describe the dining-philosophers problem and how it relates to operating systems.

In the structure of the producer process shown in Figure 7.1, what would be a possible outcome if wait(empty) is replaced with signal(empty) and signal(full) is replaced with wait(full)?

A(n) ___________ is a sequence of read-write operations that are atomic.

A thread using POSIX condition variables, a thread

Dispatcher objects in Windows are used for synchronization outside the kernel.

To lock the kernel on a single processor machine in Linux, kernel preemption is disabled.

A key difference between Reentrant locks and JAVA monitor's synchronized statements is that

Explain how Linux manages race conditions on single-processor systems such as embedded devices.

POSIX unnamed semaphores can be shared either only by threads with in a single process, or between processes.

In JAVA, calling a synchronized method always blocks the calling thread.

Explain the difference between the first readers-writers problem and the second readers--writers problem.

An advantage of using transactional memory is that

With reentrant locks, programming construct try and finally is used to ensure that unlock( ) is called even when an exception occurs in the critical section.

Alternate approaches such as transactional memory or OpenMP are useful, because

A critical section object in the user mode needs kernel intervention to ensure mutual exclusion.

Describe how a critical-section object functions.

Explain what will happen if a process A locks the associated mutex before calling pthread cond wait( ), but another process B does not lock the associated mutex before call pthread_cond_signal( ).

Critical-section compiler directive in OpenMP is generally considered easier to use than standard mutex locks, because

Explain the role of the variable preempt_count in the Linux kernel.

In a single processor system running Windows, when the kernel accesses a global resource, it

Introduction

Operating-System Structures

Processes

Threads Concurrency

Cpu Scheduling

Synchronization Tools

Deadlocks

Main Memory

Virtual Memory

Mass-Storage Structure

Io Systems

File-System Interface

File-System Implementation

File-System Internals

Security

Protection

Filters