Operating Systems Process and PCB Quiz

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Questions and Answers

Which of the following actions is NOT related to process management?

Creating processes

Compiling source code (correct)

Scheduling processes

Terminating processes

What defines a process in an operating system?

A static collection of memory allocations

A group of related tasks running simultaneously

A program in execution that progresses sequentially (correct)

A program in a non-executing state

Which interprocess communication method is based on using shared memory?

Sockets

Remote procedure calls

Pipes

POSIX shared memory (correct)

What best describes client-server communication methods?

They typically involve sockets and remote procedure calls. (D) Signup and view all the answers

In the context of operating systems, what is a primary purpose of process scheduling?

To manage the execution order of processes efficiently (D) Signup and view all the answers

What does a program become when it is loaded into memory?

Process (C) Signup and view all the answers

Which of the following is NOT a state of a process?

Sleeping (A) Signup and view all the answers

What section of memory contains temporary data for functions?

Stack (D) Signup and view all the answers

Which item is stored in the Data section of a program's memory layout?

Global variables (C) Signup and view all the answers

Which of the following describes a process that is currently executing instructions?

Running (D) Signup and view all the answers

When a process is waiting for some event to occur, it is in which state?

Waiting (A) Signup and view all the answers

What kind of information is contained in a Process Control Block (PCB)?

Process state (C) Signup and view all the answers

Which action can initiate the execution of a program?

Selecting the program via a graphical user interface (A) Signup and view all the answers

What does the program counter indicate in a process?

The location of the next instruction to execute (C) Signup and view all the answers

Which piece of information is NOT included in the CPU registers?

CPU usage statistics (D) Signup and view all the answers

What is the primary goal of process scheduling in an operating system?

To maximize CPU use and quickly switch processes onto the CPU core (D) Signup and view all the answers

What is the role of the wait queues in process management?

To hold processes waiting for an event, like I/O (A) Signup and view all the answers

Which of the following best describes a context switch?

The CPU switching from one process to another (A) Signup and view all the answers

Which struct is used in Linux to represent a process?

task_struct (D) Signup and view all the answers

What does the 'ready queue' contain?

Processes residing in main memory that are ready to execute (C) Signup and view all the answers

Which of the following information is included in accounting information for a process?

CPU time used by the process (B) Signup and view all the answers

What occurs during a context switch?

The state of the old process is saved and the new process state is loaded. (D) Signup and view all the answers

How does context-switch time relate to operating system complexity?

Increased complexity in the OS and PCB leads to longer context-switch time. (A) Signup and view all the answers

What limits are imposed by the iOS mobile system for multitasking?

Only one foreground process can be active at a time. (A) Signup and view all the answers

How does Android handle background processing compared to iOS?

Android has fewer limits on background processes and allows services to run. (D) Signup and view all the answers

What is a key characteristic of context-switching time?

It is considered pure overhead with no useful work done. (B) Signup and view all the answers

What effect does hardware support have on context switching?

It allows for multiple contexts to be loaded at once through additional registers. (D) Signup and view all the answers

In the context of process management, what does PCB stand for?

Process Control Block (B) Signup and view all the answers

What defines the behavior of background processes in iOS?

They are limited to specific short and long-running tasks. (B) Signup and view all the answers

Study Notes

Process Concept

A process is a program in execution.
A program is a passive entity stored on disk and a process becomes active when loaded into memory.
One program can be several processes, for example, consider multiple users executing the same program.
Process execution must progress in sequential fashion.
A process is composed of the program code, current activity (program counter, processor registers), stack (temporary data), data (global variables), and heap (dynamically allocated memory during run time).

Process State

A process can transition between different states throughout its execution.
The possible states are: new (being created), running (instructions being executed), waiting (waiting for some event), ready (waiting to be assigned to a processor), and terminated (finished execution).

Process Control Block (PCB)

The Process Control Block (PCB) contains information associated with each process.
PCB is also called the task control block.
PCB information includes: process state, program counter (location of next instruction to execute), CPU registers, CPU scheduling information (priorities, scheduling queue pointers), memory management information (memory allocated to the process), accounting information (CPU used, clock time elapsed since start, time limits), and I/O status information (I/O devices allocated to process, list of open files).

Process Scheduling

The process scheduler selects which process should be executed next on the CPU core.
Goals of process scheduling include maximizing CPU use and quickly switching processes onto the CPU core.
The process scheduler maintains scheduling queues of processes:
- Ready queue containing processes residing in main memory and ready to execute
- Wait queue holding processes waiting for an event (i.e., I/O)
Processes migrate among the various queues based on their state.

Context Switch

When the CPU switches to another process, a context switch occurs, saving the state of the old process and loading the saved state for the new process.
The context of a process is represented in the PCB.
Context switch is pure overhead, as the system does no useful work during the switch.
The more complex the OS and the PCB, the longer the context switch.
Hardware support can influence context switch time. Some hardware provides multiple sets of registers per CPU, allowing multiple contexts to be loaded at once.

Multitasking in Mobile Systems

Some mobile operating systems (e.g., early iOS versions) restrict execution to one process at a time, while others are suspended.
The user interface of iOS limits it to a single foreground process controlled by the user and multiple background processes in memory with restrictions.
iOS background processes are subject to limits including single, short task, receiving notification of events, and specific long-running tasks (e.g., audio playback).
Android allows foreground and background processes with fewer limitations compared to iOS.
Background processes in Android can use services to perform tasks.
A service can keep running even if the background process is suspended and has no user interface with small memory usage.

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Description

Test your knowledge on the concepts of processes, their states, and the significance of the Process Control Block (PCB) in operating systems. This quiz will cover key definitions and features of processes in execution, including their transitions and management. Challenge yourself to understand how processes function and are controlled within the OS.