Processes Chapter Quiz

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Questions and Answers

What is the primary function of a process in an operating system?

To execute instructions in a sequential manner (correct)

To store data variables permanently

To simply hold program code on disk

To allocate memory for the operating system

Which section of a process's memory is primarily used for dynamic memory allocation?

Heap (correct)

Text section

Stack

Data section

Which process state indicates that the process is waiting for some event to occur?

Waiting (correct)

Running

Terminated

Ready

What does the Process Control Block (PCB) NOT include information about?

Registered user name Signup and view all the answers

What is stored in the Text section of a process's memory?

Compiled program code Signup and view all the answers

Which term refers to the unique identification number assigned to each process in the operating system?

Process Number Signup and view all the answers

In which state is a process when it is ready to execute but not yet assigned to a processor?

Ready Signup and view all the answers

Which information is related to how long resources are allocated to a process?

Accounting information Signup and view all the answers

What is the primary role of a long-term scheduler in process management?

It controls the degree of multiprogramming. Signup and view all the answers

Which queue holds processes that are blocked due to unavailable I/O devices?

Device queue Signup and view all the answers

What does a short-term scheduler primarily do?

It allocates CPU to selected processes. Signup and view all the answers

In which queue are new processes initially placed?

Job queue Signup and view all the answers

What is the main objective of the job scheduler regarding job types?

To provide a balanced mix of I/O bound and CPU bound jobs. Signup and view all the answers

Which statement best describes a good process in the context of a long-term scheduler?

A process that integrates both I/O bound and CPU bound characteristics. Signup and view all the answers

Which of the following is NOT a function of the process scheduling system?

Control the input and output operations of processes. Signup and view all the answers

What structure is used to implement the ready queue?

Linked List Signup and view all the answers

What role does medium-term scheduling play in the management of processes?

It is part of swapping and helps to reduce the degree of multiprogramming. Signup and view all the answers

What does the fork() system call do in process management?

Creates a new process and returns the process ID. Signup and view all the answers

In process creation, what defines the relationship between a parent process and a child process?

The parent process creates one or more child processes. Signup and view all the answers

What happens to processes when the ready queue is empty?

Processes can still be swapped in from secondary memory. Signup and view all the answers

What does the term 'Address Space' refer to in context with processes?

The range of addresses accessible to a processor or reserved for a process. Signup and view all the answers

Which statement is true about how parent and child processes execute?

Parent and child processes execute concurrently by default. Signup and view all the answers

If the fork() system call returns a negative value, what does it indicate?

The creation of a child process was unsuccessful. Signup and view all the answers

What is a key characteristic of the resources shared between a parent and child process?

The child process inherits all resources of the parent. Signup and view all the answers

What is the primary function of Process Scheduling?

To keep the CPU busy at all times and minimize response time Signup and view all the answers

What occurs during a context switch?

The process state is saved and a new process state is loaded Signup and view all the answers

Which of the following is NOT a characteristic of context switching?

It allows the old process to continue execution Signup and view all the answers

In which scenario does pre-emptive scheduling occur?

When the process whose time quantum has expired is swapped out Signup and view all the answers

What is a direct cost of context switching?

The number of CPU cycles required for load/store operations Signup and view all the answers

Process Control Blocks (PCBs) hold information regarding which of the following?

CPU registers and memory-management details Signup and view all the answers

Which of the following reflects a characteristic of non-preemptive scheduling?

Processes voluntarily yield control of the CPU when necessary Signup and view all the answers

Why should the frequency of context switching be limited?

Frequent context switching incurs unnecessary overhead and slows down system performance Signup and view all the answers

What does the fork() system call return to the parent process?

The process ID of the child process Signup and view all the answers

What is one reason a parent process may terminate its child processes?

The child has exceeded allocated resources Signup and view all the answers

Which function allows a parent process to block until a child terminates?

wait() Signup and view all the answers

What happens to a child process if its parent terminates without waiting?

The child process is inherited by init Signup and view all the answers

What is a characteristic of a zombie process?

It has completed execution but not yet been reaped by the parent Signup and view all the answers

What may cause a system to terminate processes?

Insufficient memory for spawning new processes Signup and view all the answers

What does the exit() function do in relation to process termination?

It de-allocates system resources and ends the process Signup and view all the answers

When does cascading termination occur?

When the parent process exits and all its children are terminated Signup and view all the answers

Study Notes

Process Concept

A process is an active instance of a program, unlike a program which is passive and stored on disk.
Key components of a process include the program counter, stack, and data section.
Process execution follows a sequential order.

Process Memory Structure

Memory for a process is divided into four sections:
- Text Section: Contains the compiled program code.
- Data Section: Holds global and static variables.
- Heap: Used for dynamic memory allocation.
- Stack: Stores local variables.

Process States

Processes change states during execution:
- New: The process is being created.
- Ready: The process is ready to execute but waiting for CPU.
- Running: Instructions are actively being executed.
- Waiting: The process is waiting for an event or resource.
- Terminated: The process has finished execution.

Process Control Block (PCB)

The PCB contains essential information for managing a process, including:
- Process state and pointer to the parent process.
- Program counter for the next instruction.
- Unique process identifier (PID) and CPU registers.
- Scheduling information including process priority.
- Memory management and accounting details.
- I/O status with a list of devices allotted to the process.

Context Switch

A context switch involves saving the state of the current process and loading the state of a new process.
The context is represented in the PCB and includes CPU registers and memory management data.
Context switching incurs overhead and can take between 1 to 1000 microseconds, impacting overall system efficiency.

Process Scheduling

Process scheduling determines which process in the ready state should move to running.
Aims for maximal CPU utilization and minimal response time for programs.
Types of scheduling:
- Non-pre-emptive: The running process voluntarily yields the CPU.
- Pre-emptive: The OS interrupts a running process to give CPU to another.

Scheduling Queues

PCBs are maintained in various scheduling queues:
- Job Queue: Contains all processes in the system.
- Ready Queue: Holds processes ready for execution in main memory.
- Device Queues: Contains blocked processes awaiting I/O device availability.

Schedulers

Special system software responsible for process scheduling, categorized into:
- Long-Term Scheduler (Job Scheduler): Controls the admission of processes into the system and manages multiprogramming degree.
- Short-Term Scheduler (CPU Scheduler): Allocates CPU to ready processes and operates frequently.
- Medium-Term Scheduler: Manages swapping processes to control the degree of multiprogramming.

Process Creation

Involves parent processes creating child processes, forming a hierarchical structure.
Each process is assigned a PID and retains the parent PID for reference.
Processes can share resources or operate independently based on design.

Fork and Execution

The fork() system call creates child processes; its return value indicates success or failure.
Parent processes can either wait for child termination or run concurrently.
A child process may be a duplicate of its parent or have a new program loaded.

Process Termination

Processes terminate by executing the last statement and invoking the exit() system call, releasing resources.
A parent process can abort child processes under specific conditions.
Processes may also terminate due to system constraints or intervention.
Orphan and zombie processes arise from improper terminations; orphans are managed by the init system process, while zombies are cleaned up post-parent termination.

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Test your understanding of processes in computer systems, covering concepts such as process scheduling and operations. This quiz will challenge your knowledge about what defines a process and its execution dynamics.