TOP Operating System Interview Questions and Answers
Explain the main purpose of an operating system?
Operating systems exist for two main purposes. One is that it is designed to make sure a computer system performs well by managing its computational activities. Another is that it provides an environment for the development and execution of programs.
What is demand paging?
Demand paging is referred when not all of a process’s pages are in the RAM, then the OS brings the missing(and required) pages from the disk into the RAM.
What are the advantages of a multiprocessor system?
With an increased number of processors, there is considerable increase in throughput. It can also save more money because they can share resources. Finally, overall reliability is increased as well.
What is kernel?
Kernel is the core of every operating system. It connects applications to the actual processing of data. It also manages all communications between software and hardware components to ensure usability and reliability.
What are real-time systems?
Real-time systems are used when rigid time requirements have been placed on the operation of a processor. It has well defined and fixed time constraints.
What is virtual memory?
Virtual memory is a memory management technique for letting processes execute outside of memory. This is very useful especially is an executing program cannot fit in the physical memory.
Describe the objective of multiprogramming.
The main objective of multiprogramming is to have process running at all times. With this design, CPU utilization is said to be maximized.
What are time sharing systems?
In a Time sharing system, the CPU executes multiple jobs by switching among them, also known as multitasking. This process happens so fast that users can actually interact with each program while it is running.
What is SMP?
SMP is short for Symmetric MultiProcessing, and is the most common type of multiple-processor systems. In this system, each processor runs an identical copy of the operating system, and these copies communicate with one another as needed.
How are server systems classified?
Server systems can be classified as either computer-server systems or file server systems. In the first case, an interface is made available for clients to send requests to perform an action. In the second case, provisions are available for clients to create, access and update files.
What is asymmetric clustering?
In asymmetric clustering, a machine is in a state known as hot standby mode where it does nothing but to monitor the active server. That machine takes the active server’s role should the server fails.
What is a thread?
A thread is a basic unit of CPU utilization. In general, a thread is composed of a thread ID, program counter, register set and the stack.
Give some benefits of multithreaded programming.
– there is an increased responsiveness to the user
– resource sharing within the process
– utilization of multiprocessing architecture
Briefly explain FCFS.
FCFS is short for First-come, first-served, and is one type of scheduling algorithm. In this scheme, the process that requests the CPU first is allocated the CPU first. Implementation is managed by a FIFO queue.
What is RR scheduling algorithm?
RR (round-robin) scheduling algorithm is primarily aimed for time-sharing systems. A circular queue is setup in such a way that the CPU scheduler goes around that queue, allocating CPU to each process for a time interval of up to around 10 to 100 milliseconds.
What necessary conditions can lead to a deadlock situation in a system?
Deadlock situations occur when four conditions occur simultaneously in a system: Mutual exclusion; Hold and Wait; No preemption; and Circular wait.
Enumerate the different RAID levels.
RAID 0 – Non-redundant striping
RAID 1 – Mirrored Disks
RAID 2 – Memory-style error-correcting codes
RAID 3 – Bit-interleaved Parity
RAID 4 – Block-interleaved Parity
RAID 5 – Block-interleaved distributed Parity
RAID 6 – P+Q Redundancy