Below are 30 Operating System Interview Questions:
What is an operating system?
Answer: An operating system is system software that manages computer hardware, software resources, and provides various services for computer programs.
Answer: The main functions include process management, memory management, file system management, device management, and security.
Explain the difference between multitasking and multiprogramming.
Answer: Multitasking involves executing multiple tasks concurrently, while multiprogramming involves loading multiple programs into memory for execution.
What is a process?
Answer: A process is an instance of a program in execution. It consists of the program code, data, and the current program counter.
What is a thread?
Answer: A thread is a lightweight, independent unit of execution within a process. Multiple threads can exist within a single process, sharing the same resources.
What is virtual memory?
Answer: Virtual memory is a memory management technique that provides an “idealized abstraction of the storage resources that are actually available on a given machine” which creates the illusion to users of a very large memory.
Explain the difference between primary memory and secondary memory.
Answer: Primary memory (RAM) is volatile and used for temporary storage, while secondary memory (hard drives, SSDs) is non-volatile and used for long-term storage.
What is a file system?
Answer: A file system is a way of organizing and storing files on a storage device, providing a hierarchical structure and metadata for file management.
What is a deadlock?
Answer: A deadlock is a situation where two or more processes are unable to proceed because each is waiting for the other to release a resource.
Explain the concept of thrashing.
Answer: Thrashing occurs when a computer’s virtual memory system is in a constant state of paging, resulting in excessive disk I/O and poor overall performance.
What is a semaphore?
Answer: A semaphore is a synchronization primitive used to control access to a resource in a multi-process or multi-threaded environment.
Differentiate between process and thread.
Answer: A process is an independent program in execution, while a thread is a smaller unit of a process, sharing the same resources with other threads in that process.
Explain the role of the scheduler.
Answer: The scheduler is responsible for selecting the next process/thread to be executed, based on scheduling algorithms like FCFS, Round Robin, etc.
What is paging?
Answer: Paging is a memory management scheme that eliminates the need for contiguous allocation of physical memory by dividing it into fixed-size blocks called pages.
Define cache memory.
Answer: Cache memory is a small-sized type of volatile computer memory that provides high-speed data access to a processor and stores frequently used computer programs, applications, and data.
What is the role of the I/O Manager in an operating system?
Answer: The I/O Manager is responsible for managing input and output operations, including handling device drivers and interrupt requests.
What is a system call?
Answer: A system call is a request made by a program to the operating system for a specific service, such as reading or writing to a file.
Explain the concept of virtualization.
Answer: Virtualization is the creation of a virtual (rather than actual) version of something, such as an operating system, server, storage device, or network resource.
What is the purpose of the bootstrap program?
Answer: The bootstrap program is responsible for loading the operating system into the computer’s main memory during the boot process.
What is a device driver?
Answer: A device driver is a specialized program that allows higher-level computer programs to communicate with a hardware device.
Describe the difference between fragmentation and paging.
Answer: Fragmentation is the division of memory into segments, leading to inefficient use of memory. Paging, on the other hand, uses fixed-size blocks (pages) to overcome fragmentation.
What is the difference between a monolithic kernel and a microkernel?
Answer: In a monolithic kernel, the entire operating system runs in kernel mode, while in a microkernel, only essential functions run in kernel mode, and other services are implemented as user-level processes.
What is a context switch?
Answer: A context switch is the process of saving and restoring the state of a CPU so that multiple processes can be executed concurrently.
Explain the concept of time-sharing.
Answer: Time-sharing allows multiple users to share a computer simultaneously, with the operating system dividing the CPU time among different users.
What is the purpose of the page table?
Answer: The page table is used in virtual memory systems to map virtual addresses to physical addresses.
What is a deadlock prevention technique?
Answer: Deadlock prevention techniques involve preventing one of the necessary conditions for deadlock formation, such as ensuring no process holds a resource while waiting for another.
What is the purpose of the RAID system?
Answer: RAID (Redundant Array of Independent Disks) is a storage technology that combines multiple disk drive components into a logical unit to improve data redundancy, performance, or both.
What is a watchdog timer?
Answer: A watchdog timer is a hardware or software timer that triggers a system reset or other corrective action if a process fails to respond within a predefined time frame.
Explain the concept of a real-time operating system.
Answer: A real-time operating system is designed to meet specific timing constraints and deadlines, making it suitable for applications that require immediate and deterministic responses.
How does a preemptive and non-preemptive scheduling differ?
Answer: In preemptive scheduling, the operating system can interrupt a currently running process and start or resume another, while in non-preemptive scheduling, a process continues to run until it voluntarily relinquishes the CPU or terminates.