COE128 Exam - 3

Question 1

It is a basic unit of CPU utiilization

Answer 1

Thread

Question 2

A thread is composed of:

Answer 2

• A Thread ID
• A Program Counter
• A Register Set
• A Stack

Question 3

Benefits of Multithreading

Answer 3

• Responsiveness
• Resource Sharing
• Economy
• Scalability

Question 4

Multithreading an interactive application may allow a program to continue running even if part of it is blocked or is performing a lengthy operation, thereby increasing responsiveness to the user

Answer 4

Responsiveness

Question 5

Thread share the memory and the resources of the process to which they belong by default. The benefit of sharing code and data is that it allows an application to have several different threads of activity within the same address space

Answer 5

Resource Sharing

Question 6

Allocating memory and resource for process creation is costly. Because threads share the resources of the process to which they belong, it is more economical to create and context-switch threads.

Answer 6

Economy

Question 7

The benefits of multithreading can be greatly increased in a multiprocessor architecture, where threads may be running in parallel on different processors

Answer 7

Scalability

Question 8

Types of Threads

Answer 8

• User Thread
• Kernel Thread

Question 9

Supported above the kernel and are managed without kernel support

Answer 9

User Threads

Question 10

Supported and managed directly by the operating system

Answer 10

Kernel Threads

Question 11

Three (3) common ways of establishing relationship between user thread and kernel threads.

Answer 11

• Many-to-One Model
• One-to-One Model
• Many-to-Many Model

Question 12

Thread management is done by the _________ in user space, so it is efficient

Answer 12

Thread Library

Question 13

Disadvantages of Many-to-One Model

Answer 13

• The entire process will block if a thread makes a blocking system call.
• Because only one thread can access the kernel at a time, multiple threads are unable to run in parallel on the multiprocessor.

Question 14

Disadvantages of One-to-One Model

Answer 14

• Creating a user thread requires creating the corresponding kernel thread.
• Number of threads per process is sometimes restricted due to overload.

Question 15

When a thread performs a blocking system call, ___________________.

Answer 15

the kernel can schedule another thread for execution.

Question 16

Allows a single CPU core to handle multiple threads simultaneously.

Answer 16

Simultaneous Multithreading (SMT)

Question 17

It is used to retrieve the number of CPU cores and number of logical processors on a Windows System.

Answer 17

Windows Management Instrumentation Command-line (WMIC) tool

Question 18

This system call is used to create a separate duplicate process.

Answer 18

fork()

Question 19

When an _________ system call is invoked, the program specified in the parameter to _______ will replace the entire process - including all threads.

Answer 19

exec()