CSIT-345 Comprehensive Midterm Study Guide

Operating System

Software managing computer hardware and software resources.

Goals of Operating System

Efficiency, user convenience, and resource management.

Components of Computer System

Hardware, software, and user interface elements.

User View vs System View

User view focuses on usability; system view on functionality.

Kernel

Core component of an operating system managing resources.

Device Controller

Manages device operations and communicates with the CPU.

Interrupt

Signal indicating an event requiring immediate attention.

Device Driver

Software enabling communication between OS and hardware devices.

Interrupt Service Routine (ISR)

Code executed in response to an interrupt.

Interrupt Vector

Table mapping interrupts to their corresponding ISRs.

Features of Interrupt-Driven OS

Efficient resource management and responsive user interaction.

Nonmaskable Interrupt

Cannot be ignored; critical for system stability.

Maskable Interrupt

Can be ignored or delayed by the CPU.

Caching

Storing frequently accessed data for faster retrieval.

Direct Memory Access (DMA)

Allows devices to access memory without CPU intervention.

CPU Core

Basic processing unit of a CPU executing instructions.

2 Types of Multiprocessor Systems

Symmetric and asymmetric systems based on resource sharing.

Advantages of Multicore Design

Improved performance and energy efficiency in processing.

Graceful Degradation

System maintains functionality despite component failures.

Fault Tolerance

Ability to continue operation despite faults.

Asymmetric Cluster

Nodes perform different roles; not identical in function.

Symmetric Cluster

All nodes perform the same tasks and roles.

Mode Bit

Indicates current operating mode of the CPU.

Program vs Process

Program is static; process is dynamic execution instance.

Program Counter

Register tracking the next instruction to execute.

Single vs Multithreaded Process

Single requires one program counter; multithreaded needs multiple.

Data Migration

Transferring data between storage locations or systems.

Cache Coherency

Ensures consistency of data stored in cache.

Protection vs Security

Protection prevents unauthorized access; security ensures data integrity.

User and Group Control Methods

Access control lists, permissions, and authentication mechanisms.

Operating System Services

File management, process management, and device management.

I/O Operations vs File System Manipulation

I/O involves data transfer; file manipulation involves data management.

Resource Allocation

Assigning resources like CPU, memory, and I/O to processes.

System Call

Request for service from the operating system.

System Call Sequence

Steps to perform operations like file copying.

System Call Interface

Gateway for user programs to request OS services.

Parameter Passing Methods

Registers, stack, and block; stack preferred for simplicity.

printf() System Call

Invokes output operation to display formatted text.

Single Task System

Handles one task at a time.

Multitask System

Handles multiple tasks concurrently.

Object Files

Compiled code ready for linking into an executable.

Linker

Combines object files into a single executable.

Loader

Loads executable files into memory for execution.

Relocation

Adjusting addresses in code for memory placement.

Dynamically Linked Libraries

Shared libraries loaded at runtime for efficiency.

OS Development Requirements

Divided into functionality, performance, and usability.

OS Design Principle

Simplicity and modularity enhance maintainability.

OS Structures

Monolithic, microkernel, layered, and modular designs.

Modules

Self-contained components improving code organization.

Process Memory Sections

Divided into text, data, heap, and stack.

Activation Record

Data structure storing function call information on stack.

Process States

New, ready, running, waiting, terminated.

Process Control Block (PCB)

Data structure storing process information and state.

2 Process Scheduling Objectives

Maximize CPU utilization and minimize response time.

Process Scheduler

Allocates CPU to processes based on scheduling algorithms.

Scheduling Queues

Ready, waiting, and terminated queues managed by scheduler.

Degree of Multiprogramming

Number of processes in memory simultaneously.

CPU Scheduler

Selects which process to execute next.

I/O Bound Process

Spends more time waiting for I/O than computing.

CPU-Bound Process

Spends more time computing than waiting for I/O.

Context Switch

Switching CPU from one process to another.

Process Representation

Processes represented by PCB in the system.

Resource Allocation for Process

Resources allocated during process creation.

Parent Process Termination

Must release resources and terminate child processes.

Independent Process

Operates without relying on other processes.

Cooperating Process

Requires synchronization with other processes.

Process Cooperation Reasons

Resource sharing, communication, and data consistency.

Interprocess Communication Models

Message passing and shared memory for data exchange.

Synchronization Issues

Race conditions and deadlocks in shared memory.

Producer-Consumer Paradigm

Model for managing shared resources between processes.

Indirect Communication Method

Uses shared data structures for message exchange.

Blocking vs Nonblocking Message Passing

Blocking waits for message; nonblocking proceeds immediately.

Remote Procedure Calls

Enables execution of code on remote systems.

Types of Pipes

Anonymous and named pipes for interprocess communication.

Thread

Lightweight process with its own execution context.

Concurrency in Single vs Multicore

Single core executes tasks sequentially; multicore concurrently.

Types of Parallelism

Data and task parallelism for performance improvement.

Amdahl's Law

Formula to calculate speedup in parallel processing.

User Threads

Managed by user-level libraries, not OS.

Kernel Threads

Managed directly by the operating system.

User vs Kernel Thread Relationships

One-to-one, many-to-one, one-to-many, and hybrid models.

Asynchronous vs Synchronous Threading

Asynchronous allows non-blocking operations; synchronous waits.

Create/Join Strategy

Thread creation and synchronization method.

Implicit vs Explicit Threading

Implicit threading is automatic; explicit requires programmer control.

Methods for Implicit Threading

Task pools, thread pools, and futures.

Signal

Notification sent to a process to trigger action.

Asynchronous Signal

Delivered at any time; does not block execution.

Synchronous Signal

Delivered at a specific point in execution.

Default Signal Handler

Kernel-defined action taken when a signal is received.

Signal Delivery

Determined by the target process's signal handler.

Thread Cancellation

Terminating a thread before its completion.

Asynchronous Cancellation

Immediate thread termination regardless of state.

Deferred Cancellation

Thread checks for cancellation request before terminating.

Lightweight Process

Thread with minimal overhead for context switching.

Event Triggering Upcall

Notification to a process on event occurrence.

Nonpreemptive Scheduling

Running process cannot be interrupted.

Preemptive Scheduling

Allows interruption of running processes for others.

Dispatcher Job

Transfers control to the selected process.

Scheduling Algorithms

FCFS, SJF, and Round Robin for process management.

Average Wait Time Calculation

Total wait time divided by number of processes.