Operating System Concepts

This set of flashcards covers key concepts related to operating systems, including processes, scheduling algorithms, synchronization mechanisms, and deadlock management.

What is the difference between abstraction and virtualization?

Abstraction simplifies complex systems by hiding details, while virtualization simulates hardware or software resources to create separate environments.

What factors determine the time to complete computations with multiprogramming and time-sharing?

The time depends on whether the processes are compute-bound or I/O-bound.

What is the kernel in an operating system?

The kernel is the core component that manages system resources and communication between hardware and software.

What are privileged instructions?

Privileged instructions are commands that can only be executed by the kernel, often to manage hardware or system resources.

Describe the difference between kernel mode and user mode.

Kernel mode has full access to hardware and system resources, while user mode restricts access for safety and stability.

What are system calls?

System calls are the mechanism by which a program requests a service from the operating system's kernel.

What is Moore's Law?

Moore's Law states that the number of transistors on a microchip doubles approximately every two years, leading to increased performance.

How have advances in hardware technologies affected operating systems?

Advances have led to improved resource management, increased multitasking capability, and more sophisticated process scheduling.

What are SaaS, PaaS, and IaaS in cloud computing?

SaaS is software as a service, PaaS is platform as a service, and IaaS is infrastructure as a service, differing in what they provide.

Define open-source software.

Open-source software is software whose source code is available for modification and distribution.

What is a process in an operating system?

A process is an instance of a program in execution, encompassing the program code and its current activity.

What is a process control block (PCB)?

A PCB is a data structure that stores information about a process, such as its state, registers, and memory management.

What does a context switch refer to?

A context switch is the process of storing and restoring the state (context) of a CPU so that multiple processes can share a single CPU.

What is the benefit of a virtual CPU?

A virtual CPU allows multiple processes to execute concurrently without interfering with each other, improving resource utilization.

What are the main components of a generic process control block (PCB)?

Main components include process state, process ID, CPU registers, memory management information, and scheduling information.

What is a resource control block (RCB)?

An RCB contains information about resources like CPU, memory, and I/O devices that a process can access.

Define a thread.

A thread is the smallest unit of processing that can be scheduled by an operating system.

Compare a single-threaded process to a multi-threaded process.

A single-threaded process has one thread of execution while a multi-threaded process can execute multiple threads concurrently.

What is the difference between user-level threads and kernel-level threads?

User-level threads are managed by a user-space library, while kernel-level threads are managed by the operating system.

Differentiate between long-term and short-term scheduling.

Long-term scheduling decides which processes are admitted to the system, while short-term scheduling decides which process to execute next.

What is the difference between preemptive and non-preemptive scheduling?

Preemptive scheduling allows a process to be interrupted and moved to the ready state, while non-preemptive scheduling runs a process until it blocks or completes.

How does priority affect scheduling in operating systems?

Priority affects which process is selected for execution, with higher priority processes getting preference in scheduling.

What is FIFO scheduling?

FIFO (First-In-First-Out) schedules processes in the order they arrive in the ready queue.

What is Shortest Job First (SJF) scheduling?

SJF scheduling selects the process with the smallest estimated run time to execute next.

What is a turnaround time?

Turnaround time is the total time taken from submission to completion of a process.

What is starvation in scheduling?

Starvation occurs when a process is perpetually denied the resources it needs to proceed with execution.

Describe Round-Robin scheduling.

Round-Robin scheduling allocates CPU time slices to each process in the ready queue in a cyclic order.

What is the effect of time quantum on scheduling performance?

The time quantum influences response time and context switch frequency, affecting overall system performance.

What are issues related to scheduling real-time processes?

Issues include ensuring each input is processed within specific time intervals to meet deadlines.

Describe the Rate Monotonic scheduling algorithm.

Rate Monotonic scheduling assigns priorities to tasks based on their periodicity, with more frequent tasks receiving higher priority.

What is priority inversion?

Priority inversion occurs when a lower-priority process holds a resource needed by a higher-priority process.

What is the critical section problem?

The critical section problem involves ensuring that multiple processes can access shared resources without conflict.

What is a semaphore?

A semaphore is a synchronization primitive that is used to control access to a common resource in concurrent processes.

Describe a monitor in the context of synchronization.

A monitor is a high-level synchronization construct that allows safe access to shared resources through condition variables.

What is a deadlock?

Deadlock is a situation where two or more processes are unable to continue because each is waiting for the other to release resources.

Differentiate between deadlock and starvation.

Deadlock involves processes permanently blocking each other, while starvation refers to a process being perpetually denied resources.

What is a safe state in deadlock management?

A safe state is a condition where the system can allocate resources to each process in some order without leading to deadlock.

What conditions must be met for deadlock to occur?

Conditions include mutual exclusion, hold and wait, no preemption, and circular wait.