CS 241 - Operating System: Process Concept

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Questions and Answers

What is the primary requirement for process execution?

Sequential execution of instructions (correct)

Parallel execution of instructions

Concurrent execution of multiple programs

Simultaneous execution of multiple processes

What is the primary purpose of the stack in a process's memory layout?

Storing global variables

Storing program code

Storing dynamically allocated memory

Temporary data storage when invoking functions (correct)

What is the difference between a program and a process?

A program is stored on disk, while a process is stored in memory

A program is active, while a process is passive

A program is executed by the CPU, while a process is executed by the OS

A program is passive, while a process is active (correct)

What is the purpose of the data section in a process's memory layout?

Storing global variables Signup and view all the answers

What is the role of the program counter in a process's execution?

It represents the current status of the process's activity Signup and view all the answers

What is a key distinction between the initialized and uninitialized data sections in a process's memory layout?

The initialized data section contains initialized values, while the uninitialized data section contains uninitialized values Signup and view all the answers

What is the maximum number of processes that can be associated with a link?

Two Signup and view all the answers

In a non-blocking send operation, what happens after the sender sends the message?

The sender continues executing Signup and view all the answers

What is the characteristic of a zero-capacity buffer?

No messages are queued on a link Signup and view all the answers

What is the term for when both send and receive are blocking?

Rendezvous Signup and view all the answers

What is the characteristic of an unbounded capacity buffer?

It can queue an infinite number of messages Signup and view all the answers

What is the limitation of ordinary pipes?

They cannot be accessed from outside the process that created it Signup and view all the answers

What information is typically stored in a Process Control Block (PCB)?

List of I/O devices allocated to the process, scheduling and memory-management information, and list of open files. Signup and view all the answers

What is the purpose of the field 'long state' in the task struct?

To represent the state of a process. Signup and view all the answers

What is the data structure used to represent all active processes in the Linux kernel?

A doubly linked list of task struct. Signup and view all the answers

What is the relationship between a process and its parent process?

A process is a child of its parent process. Signup and view all the answers

What is the purpose of the 'pid' field in the task struct?

To store the process ID of a process. Signup and view all the answers

What is the term for a process that is created by another process?

Child process. Signup and view all the answers

What is the primary goal of the process scheduler?

To maximize CPU usage and quickly switch processes onto the CPU core Signup and view all the answers

What type of data structure is used to store the ready queue?

Linked list Signup and view all the answers

What happens to a process when it issues an I/O request?

It is placed in an I/O wait queue Signup and view all the answers

What triggers a process to be removed from the CPU core and placed back in the ready queue?

An interrupt or the expiration of its time slice Signup and view all the answers

What is the status of a process in the wait queue?

Waiting for an event to occur Signup and view all the answers

Where is a new process initially placed in the system?

Ready queue Signup and view all the answers

What is the primary difference between named pipes and ordinary pipes?

Named pipes are bidirectional, ordinary pipes are unidirectional Signup and view all the answers

What is the purpose of a socket in a networked system?

To act as an endpoint for communication between two systems Signup and view all the answers

What is the primary function of a stub in a remote procedure call?

To locate the server and marshall the parameters for the procedure call Signup and view all the answers

What is the significance of the IP address 127.0.0.1 in socket communication?

It is used to refer to the system on which the process is running Signup and view all the answers

What is the primary difference between a socket and a pipe?

A socket is used for communication between two systems, a pipe is used for communication between two processes on the same system Signup and view all the answers

What is the purpose of port numbers in socket communication?

To differentiate between multiple services on a host Signup and view all the answers

Study Notes

Process Execution Requirements

A process requires a unique identifier (PID) and allocated memory to execute.
Memory layout includes various sections: code, stack, heap, and data.

Purpose of Stack in Memory Layout

The stack is used for function call management, including local variables and return addresses.
Supports Last In, First Out (LIFO) operation, allowing orderly function execution and exits.

Difference Between Program and Process

A program is a static set of instructions stored on disk; a process is an active execution of a program.
Multiple processes can run the same program concurrently.

Purpose of the Data Section

The data section stores global and static variables that are initialized prior to execution.
Divided into initialized and uninitialized data segments for memory management.

Role of the Program Counter

The program counter keeps track of the next instruction to be executed in a process.
It is essential for the flow of execution and maintaining order in instruction processing.

Initialized vs. Uninitialized Data Sections

Initialized data section contains variables with defined initial values.
Uninitialized data section holds variables set to zero or undefined until assigned.

Maximum Processes Associated with a Link

A link can associate a maximum of 256 processes, depending on system limitations.

Non-Blocking Send Operations

After sending a message, the sender does not wait for the receiver to acknowledge receipt.
This allows the sender to continue executing other tasks immediately.

Characteristic of a Zero-Capacity Buffer

A zero-capacity buffer does not store any messages; it requires the sender and receiver to be synchronized.

Blocking Send and Receive

Blocking send occurs when the sender waits for the receiver's acknowledgment.
Blocking receive waits for a message to be sent before proceeding with execution.

Characteristic of an Unbounded Capacity Buffer

An unbounded buffer can grow in size infinitely, accommodating as many messages as needed.

Limitation of Ordinary Pipes

Ordinary pipes provide unidirectional communication and require a direct parent-child process relationship.

Process Control Block (PCB) Information

A PCB stores process state, PID, program counter, CPU registers, memory management information, and I/O status.

Purpose of 'long state' in Task Struct

The 'long state' field indicates the current status of a process (e.g., running, waiting, or stopped).

Data Structure for Active Processes in Linux

A task struct represents all active processes, linking their PCBs for process management.

Process-Parent Relationship

Each process has a parent process that creates it, establishing a hierarchical relationship in process management.

Purpose of 'pid' Field in Task Struct

The 'pid' field uniquely identifies each process in the system, crucial for process control and management.

Term for Child Process

A process created by another process is referred to as a child process.

Primary Goal of Process Scheduler

The process scheduler aims to optimize CPU utilization, fairness, and response time among processes.

Data Structure for Ready Queue

A queue, often a linked list or array, organizes processes ready for execution by the CPU.

I/O Request Process Behavior

When a process issues an I/O request, it moves from a running state to a blocked state until the operation completes.

Trigger for Process to Leave CPU

A process is removed from the CPU when it is preempted by a higher-priority process or issues an I/O request.

Process Status in Wait Queue

A process in the wait queue is in a blocked state, waiting for a specific event or resource to proceed.

Initial Placement of New Processes

New processes are initially placed in a ready queue, awaiting CPU time for execution.

Named Pipes vs. Ordinary Pipes

Named pipes support bidirectional communication and can be accessed by unrelated processes, unlike ordinary pipes.

Purpose of Sockets in Networked Systems

Sockets facilitate communication between processes over networks, enabling data exchange between different systems.

Function of Stub in Remote Procedure Call

A stub acts as a proxy for remote procedure calls, handling communication between the client and server.

Significance of IP Address 127.0.0.1

The IP address 127.0.0.1, known as localhost, allows a device to communicate with itself for testing.

Difference Between Sockets and Pipes

Sockets provide network communication capabilities, while pipes are used for inter-process communication within the same system.

Purpose of Port Numbers in Socket Communication

Port numbers identify specific processes or services on a device, enabling targeted communication over a network.

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Description

This quiz covers the process concept in operating systems, including the definition of a process, its execution, and the representation of its status. It's based on Dr. Ahmed Hesham Mostafa's Lecture 3. Test your understanding of operating system processes!