Module 2: Processes, Threads, Resources

Question 1

Define a Process

Answer 1

A process is an instance of a program being executed by an OS.

Question 2

Define a PCB

Answer 2

The OS keeps track of each process using a PCB: A data structure that holds information for a process, including the current instruction address, the execution stack, the set of resources used, and the program being executed. The PCB is the concrete representation of a process.

Question 3

Draw and describe the process diagram and the states and transitions.

Question 4

Define a Context Switch

Answer 4

A context switch is the transfer of control from one process to another.

Question 5

Describe the benefits of a virtual CPU

Answer 5

Multi-user support,
multi-CPU transparency,
portability

Question 6

List the contents of a generic PCB

Answer 6

CPU_state, process_State, memory, scheduling_information, accounting_information, open_files, other_resources, parent, children

Question 7

Describe parent-child relationships for processes.

Answer 7

4 fields track parent child relationships: parent, first_child, younger_sibling, and older_sibling

Question 8

Define a Resource Control Block

Answer 8

an RCB is a data structure that represents a resource. A generic RCB contains: resource_description, state, and waiting_list

Question 9

Define a thread

Answer 9

A thread is an instance of executing a portion of a program within a process without incurring the overhead of creating and managing separate PCBs