Operating System Interview Questions

IPC (Interropess Communication) is a device that grows to use resources, and these are as separated memory between processes or jets. OS that supports IPC is a friend with different processes on interaction with different processes. It is mainly used to exchange data between different jets in one or more programs or processes. With this mechanism, all kinds of processes have every chance to interact with another one friend with the permission of the operating system.

All types of IPC mechanisms:

• Pipes
• Notification lines
• Semaphores
• Stop contacts
• General memory
• Signals

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2. What's the main purpose of an OS? What are the different types of OS?

The main purpose of the OS is to implement user programs, facilitate the user's perception and operation of the computer, and launch applications. It is purposefully designed to ensure the best operation of the computer system by managing all computer activities. It also controls the operation of the computer's memory, processes, and all hardware and software.

Types of OS

• Packaged OS (e. g. payroll systems, trade processes, etc.).
• Multi-programmed OS (e. g. Windows O/S, Unix O/S, etc.).
• Time-intensive OS (e. g. Multix, etc.)
• Distributed OS (Locus, etc.)
• Real-time OS (PSO, VRTX, etc.).

3. What are the benefits of a multiprocessor system?

Multiprocessor system is the expression of a system with two or more microprocessors connected together. It means that two or more microprocessors use one memory and process various computer programs simultaneously in a first-class computer system.

Advantages:

• Such systems are huge in real time to improve the system performance and generate a certain number of programs at the same time.
• The more the number of microprocessors increases, the more tasks can be performed per unit time.
• Furthermore, since all microprocessors use the same resources, it is important to increase the legal and financial effectiveness.
• This increases the reliability of the computer system.

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4. What is RAID structure in OS? What are the different levels of RAID configuration?

RAID (redundant array of an independent disk) is a method used to save data across multiple strict disks, resulting in the development of data saving that combines a certain number of strict disks. It is considered. This can balance data protection, system performance, and places for saving. Balance is used to increase data saving performance and reliability. Also, increase the capacity of the preserved system, and the main tasks are reached excess data to reduce the loss.

Raid different values

In real time, RAID is available at all types of schemes or RAID levels:

• RAID 0-Redundant alternative: This level is used to improve server performance.
• RAID 1-Mirroring and Duplication: This level is still popular as a disc mirror and is the most common way to implement disability resistance.
• RAID 2-Memory adjustment code by memory method: This level usually uses a special arrangement gaming, that is, a linear composition of the mistakes adjustment code.
• RAID 3 is an alternative parity category. A dedicated parity disk is required to save parity INFA at this level.
• RAID 4-Block Interive Parity: This level is similar to RAID 5, but only the parity data is stored on the same disk.
• RAID 5-Distributed, block exchange available: This degree guarantees a much higher performance and disability resistance than a disk mirroring.
• RAID 6-p+q Redundant: This degree is usually guaranteed by refusing two disks to guarantee disability resistance.

5. What is GUI?

The GUI (graphical user interface) is an image of a user interface that can apply graphics to interact with the OS. The GUI was created for the fact that it is more convenient and easier to understand than the command line interface. The main role of the GUI is to increase the effectiveness and ease of use. Instead of remembering the command, the user has the option of pressing a rudimentary button to perform rudimentary functions. Examples of graphical interfaces include Microsoft Windows, MacOS, and Apple IOS.

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6. What is a Pipe and when it is used?

A pipe is a binding body where two or more processes are interconnected by another friend. This is a device used for interaction between processing that supports message transfer. Pipe support allows you to easily transfer information such as the cancellation of the first program process to another software process. The pipe has the ability to use two processes on one side, that is, for interaction interaction (IPC).

7. What are the different kinds of operations that are possible on semaphore?

Hosts are likely to be two atomic operations:

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8. What is a bootstrap program in OS?

This is a program that initializes the operating system at startup, and is the first code created when the computer system is started. The operating system load is in principle with the support of a program called a download process or boot. In general, operating systems work correctly only to loader programs. The loader is completely stored when loading a block to the fixed space on the disk. Also, determine the position of the core, load it to major memory, and start implementing the program.

9. Explain demand paging?

The loading of the page according to the claim is the loading method of the page to the memory of the claim. This method of the host is used in virtual memory. With this page, it falls to the memory only when there is a call for a specific space on this page during the execution. As a general rule, an appropriate procedure is taken:

• Try access to the page.
• If the page is real (in the memory), continue manual processing in simple mode.
• If the page is invalid, the page is displayed from the page.
• Check if the hyperlink is considered a actual reference to the space in the secondary memory. Otherwise, the processing ends (unauthorized access to memory). If you are unpleasant, paste the appropriate page.
• Schedule the disk operation to read the necessary pages into the previous memory.
• Restart leadership interrupted by the Western OS.

10. What do you mean by RTOS?

Rea l-time operating systems (RTOS) are operating systems used in rea l-time applications, that is, for applications that need to be done for a short time with fixed data processing. It cools the task in a task executed in a short direction. Still, it will take on execution, prediction, and all control processes. Apart from this, there are less memory and consuming resources.

RTO type

• Difficult rea l-time
• Strong flow
• Calm rea l-time mode

RTOS are used in weightless motion control systems, anti-blocking brakes, pacemakers, etc.

11. What do you mean by process synchronization?

Process synchronization is a method of coordinating processes using shared resources or data. It is a fundamental method to ensure synchronous execution of interacting processes to maintain data consistency. Its main task is the joint implementation of resources supporting mutual exclusion and without interference. There are two similarities of process synchronization:

• Independent Processes
• Cooperative Processes

12. Why is the operating system important?

The OS is a very important and relevant part of a computer, without which it would be redundant. The OS guarantees the interface and acts as a link of interaction between the computer software installed on it and the user. It also supports interaction with the hardware and supports the balance between the hardware and the microprocessor. It also provides suggestions to the user and a platform for launching programs. It allows all the collaboration required for applications.

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13. What is different between main memory and secondary memory.

RAM: RAM (random access memory) is considered the main memory of a computer. It is still popular today as the original memory, read and record memory, and internal memory. This memory stores programs and data that the microprocessor needs during programming. Secondary memory: Secondary memory in a computer is a device for storing data and programs. It is also called external memory, additional memory, spare memory, and auxiliary memory. These storage devices are provided to protect the size of huge data. As drives, there is every chance to play strict disks, USB flash drives, CDs, etc. Playback, etc.

Primary memory	Secondary memory
The data has every chance to be immediately available to the microprocessor.	First, the data is transferred to the primary memory and then sent to the processing unit.
Its nature has the ability to be energy dependent for example.	Inherently energy dependent.
More expensive than secondary memory.	More economical than original memory or at least an overlay.
Short-term as a result of how data has been stored so far.	Constant - as data is stored daily.
With this memory, there is a chance of data loss if the power goes off.	With this memory, there is no chance of data loss even in the case of a power outage as data is stored daily.
More secondary memory protects the data currently used by the computer.	The operation is slower than the primary memory and protects all kinds of data in various formats.
You can contact the data support.	You can contact the input / output channel.

14. What do you mean by overlays in OS?

Overlay is a programming method that distinguishes processes and parts so that important and necessary notes are stored in memory. There is no need for the operating system. This allows you to run a program of the same size as the physiological memory size and protect only important data and memos.

15. Write top 10 examples of OS?

The following are part of the more commonly used operating system:

• MS-Windows
• Ubuntu
• Mac OS
• Fedora
• Solaris
• Free BSD
• Chrome OS
• Centos
• Debian
• Android

Intermediate OS Interview Questions

1. What is thrashing in OS?

This is the situation where microcessors are reducing productive jobs and spending a lot of work on swaps and paging. Micro processors spend more time on swaps and paging than their own work. By evaluating the level of the microcessor, the system has a function to identify traces. This appears when there is not enough pages in the process, increasing the frequency of page mistakes. This effectively slows down many applications, which leads to a decrease in computer productivity and failure.

2. What is the main objective of multiprogramming?

This is a legal ability to execute multiple programs on one processor machine. The technology was introduced to overcome the difficulties of the Chuo Micro processor and RAM. More simpler, it is a adjustment to execute all kinds of programs at the same time on one microcessor (CPU). The main purpose of mult i-programming is to systematically execute different processing. This is a microcessor, which improves the introduction of a rudimentary microcessesa in order to organize the large number of tasks, and each time contains one command for execution.

3. What do you mean by asymmetric clustering?

Asymmetric clustering is a system that sets one node in hot spare mode and creates all kinds of applications on other nodes. The use of all hardware resources is more reliable in comparison with other systems.

4. What is the difference between multitasking and multiprocessing OS?

Multivative: This is a system that allows computing resources to be used more effectively. This system processes several tasks at the same time and quickly switches those tasks. Such systems are still popular as a system department.

Multiprocating: This is a system in which multiple or different microcessors in the computer simultaneously culture two or more parts of one program. This is used to execute the maximum size with a larger short pair.

Multitasking	Multiprocessing
The first microprocessor supports multiple tasks to be performed simultaneously.	The second microprocessor supports multiple microprocessors to perform a certain number of tasks simultaneously.
In this case, the number of microprocessors is 1.	In this case, the number of microprocessors is more than the first.
More economical.	Less economical.
Less efficient than multiprocessing.	More effective than multitasking.
Quickly switches between different tasks.	Smoothly handles a certain number of tasks at the same time.
Takes longer to perform tasks than multiprocessing.	Takes less time to process than multitasking.

5. What do you mean by Sockets in OS?

In operating systems, sockets are usually called IPC (Interpreter Communication) endpoints. Here, the final busta is classified as an icon and port number configuration. Jewits are used for this purpose to make it easier for software writers to create programs using networks. They can also provide association and exchange of information between two different processes on one or different machines. In hosts, they are used in client-server based systems.

Socket types

There are four things that resemble sockets in the host:

• Streaming jack
• Data logic socket
• Alternate packet justice
• Raw jack

6. Explain zombie process?

A zombie process, called a non-working jack, is a process that has completed or terminated but the entire set of moves has not been cleaned by RAM, due to the fact that it contains a record in the process of the process so that it can still declare its own parent process. It consumes almost all resources and is not dead, but still. This also indicates that the resources are held by progress and are not considered free.

7. What do you mean by cascading termination?

Cascad e-end means the termination of a process where the parent process comes out or ends, but the child process remains completed. This prevents the child process from continuing the processing of the parent process, for example. As a rule, this is initiated by the operating system.

8. What is starvation and aging in OS?

With priority scheduling or planning with minimal commands, there is the ability for hangers to appear. This method in the host is used by the scheduler of the microprocessor.

Starvation:This is a state that usually appears when a process cannot secure the resources it needs to run in the long term. In this case, low-priority processes are blocked and only high-priority processes run to completion, causing the low-priority processes to suffer from resource starvation.

Staleness:This is a method used to overcome the difficulties of history and famine. Increase the value of the process waiting for resources in the system for a long time. This is the best technique for closing hunger because it adds the moment of obsolescence to the priority of any kind of request for any kind of process for resources. She still can actually end the implementation of instructions and lo w-level rows processes.

9. What is the difference between paging and segmentation?

Swating: This is a memory management technology that allows the operating system to extract the process from the secondary storage device to the preceding memory. This is a no n-industrial tuning technology that divides each process into a page. Seg maintenance: This is a memory management technology that distinguishes the process of different volumes and partially the process. These parts and modules are called sectors and are likely to be processed only.

page	segmentation
Not visible to software developers.	It looks like a software developer.
In this case, the page size is fixed.	In this case, the size of the section is not fixed.
The procedure and data may be broken by paging.	If segmented, the procedure and data may be broken.
The total number of virtual addresses is allowed to exceed the physiological top memory.	Allow all programs, data and code in an autonomous place to be destroyed.
The host is available for MMU microcesses and chips.	The host can be used on a Windows server with all the possibilities that maintains revolutionary comparison, but Linux has a limited support.
Memory access is more likely to be executed compared to segmentation.	Slower than paging.
In this case, the operating system needs to maintain an empty frame.	In this case, the operating system needs to support the list of holes in the preceding memory.
In the paging, the image of fragmentation is inside.	In the case of segmentation, the image of fragmentation is outside.
The page size is attached by the accessible memory.	The size of the page is guided by the user.

10. What is virtual memory?

This is a memory management technology in the operating system, which makes users an illusion of a very large (main) memory. This is a rudimentary place that has the ability to store more programs in the form of the page. This enlarges the introduction of physiological memory by using disk, and is guaranteed memory protection. In the operating system, it can control in two widespread methods, pumping and segmentation. It functions as a temporary storage device and can be used continuously with the computer process RAM.

11. What is thread in OS?

A thread is an execution path that consists of a program counter, a personal thread number, a stack, and a set of registers from within a process. This allows for more efficient and effective data replacement, allows for larger and more efficient multiprocessor architectures, and reduces the time required for context switching. This is an easy way to improve and enhance the performance of an application through parallel processing. Jets are sometimes called lightweight processes because they have a private personal stack but have the ability to access aggregated information.

Multiple threads running in the same process share address space, sets, static data, code sections, file handles, bulk variables, underlying process, wait signals, signals, and signal handlers.

Each thread has its own information, such as program counter, registers, stack, and position.

12. What is a process? What are the different states of a process?

A process is basically a program that is currently running. The main function of an operating system is to manage and handle all process data. When a program is loaded into memory and executed, it is divided into four parts: stack, set, word, and data. There are two similar processes:

1. Operating System Process
2. User Process

Process States:

The following are the various stages a process goes through:

• New Position: In this state, the process is only actually being created.
• Created: In this state, the microprocessor starts working on the process instructions.
• Waiting: In this state, the process does not have the ability to start.
• Ready: In this state, the process has all the resources it needs to execute, but the CPU is not currently working on instructions sent by the move, so it is waiting for the microprocessor to be assigned to it.
• Finished: In this state, the process is complete, i. e., it has finished executing.

13. What do you mean by FCFS?

FCFS (First Come First Serve) describes an operating system scheduling scheme in which processes are displayed in the order in which they arrive. Simply put, the first process that arrives is the first to run. It is not considered to be throttling in nature. In FCFS scheduling, if the first process has the longest execution time of all tasks, the task may be starved. Sleep time here means the time in milliseconds it takes for the process to complete. It is also the most common and lightest-weight scheduling method in operating systems. FCFS implementations are usually done with the support of a First In First Out (FIFO) queue.

14. What is Reentrancy?

Reentry is simply the ability for all kinds of buyers to use one instance of one program towards one same period and have all the opportunities to use it together. This concept is usually related to OS code and has nothing to do with parallelism. It has two main features:

• The code of the program cannot be changed or modified.
• The local data of each client process must be stored on a separate disk.

15. What is a Scheduling Algorithm? Name different types of scheduling algorithms.

A scheduling algorithm is a process for increasing the productivity of work by using the microprocessor to its limits and reducing the waiting time of tasks. It simply solves the problem of determining which of the open requests to allocate resources to. Its main job is to reduce resource starvation and ensure loyalty between the parties using the resource. Simply put, it is used to allocate resources to multiple competing tasks.

Types of Scheduling Algorithms

There are the following types of scheduling algorithms:

Advanced OS Interview Questions

1. What are different types of Kernel?

Presenter has five types of cores:

• Monolithic core
• Microkernel
• Hybrid core
• Nanocore
• Exocore

2. What do you mean by Semaphore in OS? Why is it used?

A semaphore is a synchronization device used to control access to shared resources in a multithreaded multiprocess system. Semaphores track inexpensive resources and return two atomic operations: wait() and signal(). The counter can be greater than 1, allowing you to control access to a limited pool of resources.

Types of Semaphores

There are two types of semaphores:

• Binary Semaphores: Binary semaphores are synchronization objects that have only two meanings, 0 and 1.
• Counting Semaphores: Counting semaphores are synchronization objects that can have values ​​greater than 1. They are used to control access to a limited number of resources, such as a pool of database connections or a limited number of threads.

Binary Semaphores	Mutexes
Allow a process to signal the availability of a shared resource by setting the semaphore's value to 1, blocking other processes until the resource is readily available.	Guarantees mutual exclusion, ensuring that a thread can only lock a shared resource once at a time.
Functions are based on a signal mechanism.	Functions are based on a lock mechanism.
Binary semaphores are more likely to appear as mutexes in certain scenarios, such as when multiple processes require access to a shared resource and more than one semaphore exists.	Myutex has the ability to operate slower than binary semaphores in some cases, for example, when Mietex is demanding and block and unlock operations occur quite frequently.
Basically, it is an integer variable with the ability to hold 0 or 1.	Basically, it is an object with the ability to protect the blocking position and auxiliary information (such as the owner of the blocking and the number of jets waiting for blocking).

3. What is Kernel and write its main functions?

Core is a computer program, usually considered as the central component or OS module. It is responsible for handling, managing and controlling all the operations of the computer system and the hardware support. When booting the system, the core is the first to be loaded and remains in the top memory. It also acts as an interface between the user applications and the hardware.

Core Functions:

• Manages all the resources of the computer, such as the microprocessor, memory, files, processes, etc.
• Simplifies or activates the interaction between hardware and software components.
• Controls the RAM so that all running processes and programs can operate efficiently and effectively.
• Even today, it oversees and controls all the major tasks of the operating system and also regulates the access and introduction of any kind of peripheral device connected to the computer.
• Thus conceives the work of the microprocessor and makes each user's work potentially produce.

4. Write difference between micro kernel and monolithic kernel?

MICR O-VERSE: A minimal operating system that performs only the important functions of the operating system. It has almost a small number of probabilities and functions that are important for implementing an OS.ExamplesQNX, Mac OS X, K42, etc.

Whole-core: An operating system architecture that supports all the major functions of a part of a computer, such as managing resources, memory, files, etc.ExamplesSolaris, DOS, OpenVMS, Linux, etc.

Microkernel	Monolithic core
In this core and the software support for user services, the user services are located at different address locations.	In this core and the software support for user services, the user services are usually located at one target location.
Smaller in size compared to fixed cores.	Larger when compared to micro yards.
Easier to expand compared to solid cores.	Less likely to expand compared to micro yards.
When a service fails, microyards of work are affected.	On all cores, when a service fails, the whole system fails.
Notification queues are used to communicate between processes.	Signals and sockets are used to communicate between processes.

5. What is SMP (Symmetric Multiprocessing)?

SMP is generally called a computer architecture that performs program processing by multiple micro processors that share operating systems and memory. SMP is very important if you want to use the excellent functions of hardware equipped with multiple processors. Regardless of the task that contains data or resources for specific tasks in the memory, only the microcessors can work on any task. These systems are more reliable than single processor systems.

6. What is a time-sharing system?

This is a system that allows multiple users to access the resources of a specific system in multiple rooms. Simply put, run a lot of tasks with one microcessor or CPU. According to this name, this means dividing some slots time into a different process. It is also possible for users in different rooms to use a specific computer system at the same time, which is one of the most important types of operating systems.

7. What is Context Switching?

Context switching is a process of storing context of a process and loading a context of another process. This is one of the economic and tim e-saving means used by microcessors, which allows different processes to work together to execute a microcessor. Therefore, it is an essential element for advanced operating systems. This technology is used by the operating system to transfer the process from a certain state to another, that is, from an active state to a lady. In addition, one micro processor can manage and control various processes and flows without any additional resources.

8. What is difference between Kernel and OS?

Kernel: Kernel is a system program that manages all programs operating on a computer. Basically, kernels are considered to connect system software and hardware.

Operating System: The operating system is a system program that operates on a computer, providing an interface that users can easily work on computers.

core	OS
Components at the center of the operating system.	It is regarded as system software.
The main role is to convert the user command to a machine command.	Manage system resources.
It functions as an interface between hardware and applications.	It functions as an interface between hardware and users.
Manage processes, files, devices, input / output interaction, etc.	These functions are also performed, such as securing data and files in the system, transfer of access control to users, and maintaining system confidentiality.
Depending on the type of kernel, there are microchanels and hall kernels.	The types include single program systems, multi-program packet systems, distributed OS, real-time OS, etc.

9. What is difference between process and thread?

Process: Basically, this is a program currently being generated by one or more jets. This is a pretty important part of progressive OS.

Thread: An execution path consisting of a software counter, a personal number stream, a stack, and a set of registers inside the process.

Process	Thread
A computer program inside a running process.	A component or object of a process, considered as the shortest unit of execution.
A heavy operator.	A gentle operator.
It has a personal location in memory.	It uses the memory of the process it belongs to.
Creating a process is harder than creating a stream.	Creating a stream is easier than a process.
It requires more resources compared to a stream.	It requires less resources compared to a process.
It takes more time to create and terminate a process compared to a stream.	It takes less time to create and terminate a jet compared to a course.
It is usually generated in a different location in memory.	It is usually generated in a common location in memory.
It does not exchange data.	It exchanges different data with a friend.
It can be divided into any number of jets.	There is no facility to divide it into any number of jets.

10. What are various sections of the process?

The leading process consists of four sections:

• State: Used for local variables and return addresses.
• Lot: Used for dynamic murals.
• Data: Stores mass and static variables.
• Code or Word: Stores compiled program code.

11. What is a deadlock in OS? What are the necessary conditions for a deadlock?

A dead end is a situation where a set of processes are blocked because each process has a resource and is waiting to receive a resource at the discretion of the other process. In this story, two or more processes are sophisticated trying to be produced at the same time and are waiting for one of them to finish fulfilling because they depend on a friend of a friend. We can control the work by moving our hands in the system when a program is stuck. These are among the tasks that are commonly found in multiprocessor systems.

Conditions necessary for a dead end to occur

There are four main situations in which a host can be stuck:

• Mutual exceptions
• Retention and expectation
• Unpreparedness for ransomware
• Periodic expectation or anticipation of resources

12. What do you mean by Belady’s Anomaly?

In the operating system, process data is loaded as a fragment of a fixed volume, and each fragment is called a page. The microcessor loads these pages into memory fragments, and the fragments are referenced by the frame. Beladi's anomaly seems to increase the number of pages as the number of frames in memory is increased. As a general rule, it appears when the FIFO-page replacement method (first entry) is applied.

13. What is spooling in OS?

Spool is to operate peripheral devices online at the same time. It refers to the buffer of such a miscellaneous work of input / output. Here, the buffer is understood as a special area on a cheap memory or a strict disk in an input / output device. This is used to intermediary between computer applications and relaxed peripherals. This is quite cool and basic because the device accesses information at different speeds. In this operation, the disk is used as a pretty huge buffer, and can block an input / output operation of a task with another task processor operation.

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In general, which of the following provides an interface to access OS services? In the