1) Explain the main purpose of an operating system? Operating Top 50 Operating System Interview Questions & Answers .. Download PDF. Contains Important Operating system Interview Questions with Answers and Questions based on Operating system, check your knowledge and test your Answers PDF | Interview Questions in Operating System | Operating System eBooks. Operating Systems viva questions and answers pdf Operating Systems lab viva questions with answers pdf os viva interview questions jntu free.
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Commonly Asked Operating Systems Interview Questions | Set 1. What is a process and process table? What are different states of process. A process is an . + Operating System Interview Questions and Answers, Question1: Explain the main purpose of an operating system? Question2: What is demand paging?. Operating System Viva Questions - Download as PDF File .pdf), Text File .txt) or read for Operating System B Tech Engineering Lab Questions with Answers.
No preemption : If a process is holding some resources and requests another resource that cannot be immediately allocated to it that is the process must wait , then all the resources currently being held are preempted released autonomously. Circular wait : the way to ensure that this condition never holds is to impose a total ordering of all the resource types, and to require that each process requests resources in an increasing order of enumeration.
What is a safe state and a safe sequence? A system is in safe state only if there exists a safe sequence. A sequence of processes is a safe sequence for the current allocation state if, for each Pi, the resources that the Pi can still request can be satisfied by the currently available resources plus the resources held by all the Pj, with j What are the deadlock avoidance algorithms? A dead lock avoidance algorithm dynamically examines the resource-allocation state to ensure that a circular wait condition can never exist.
The resource allocation state is defined by the number of available and allocated resources, and the maximum demand of the process. There are two algorithms: 1. Resource allocation graph algorithm 2. Resource request algorithm What are the basic functions of an operating system? Operating system controls and coordinates the use of the hardware among the various applications programs for various uses.
Operating system acts as resource allocator and manager. Since there are many possibly conflicting requests for resources the operating system must decide which requests are allocated resources to operating the computer system efficiently and fairly.
Also operating system is control program which controls the user programs to prevent errors and improper use of the computer. Explain briefly about, processor, assembler, compiler, loader, linker and the functions executed by them. Some people call these instructions assembler language and others use the term assembly language. Typically, a programmer writes language statements in a language such as Pascal or C one line at a time using an editor.
The file that is created contains what are called the source statements. The programmer then runs the appropriate language compiler, specifying the name of the file that contains the source statements. What is a Real-Time System? A real time process is a process that must respond to the events within a certain time period. A real time operating system is an operating system that can run real time processes successfully What is the difference between Hard and Soft real-time systems?
A hard real-time system guarantees that critical tasks complete on time. This goal requires that all delays in the system be bounded from the retrieval of the stored data to the time that it takes the operating system to finish any request made of it. A soft real time system where a critical real-time task gets priority over other tasks and retains that priority until it completes. As in hard real time systems kernel delays need to be bounded What is virtual memory? A virtual memory is hardware technique where the system appears to have more memory that it actually does.
This is done by time-sharing, the physical memory and storage parts of the memory one disk when they are not actively being used What is cache memory? Cache memory is random access memory RAM that a computer microprocessor can access more quickly than it can access regular RAM.
As the microprocessor processes data, it looks first in the cache memory and if it finds the data there from a previous reading of data , it does not have to do the more time-consuming reading of data Differentiate between Complier and Interpreter? An interpreter reads one instruction at a time and carries out the actions implied by that instruction. It does not perform any translation.
But a compiler translates the entire instructions. What are different tasks of Lexical Analysis? The purpose of the lexical analyzer is to partition the input text, delivering a sequence of comments and basic symbols.
Comments are character sequences to be ignored, while basic symbols are character sequences that correspond to terminal symbols of the grammar defining the phrase structure of the input Why paging is used?
Paging is solution to external fragmentation problem which is to permit the logical address space of a process to be noncontiguous, thus allowing a process to be allocating physical memory wherever the latter is available. What is Context Switch? Switching the CPU to another process requires saving the state of the old process and loading the saved state for the new process.
This task is known as a context switch. Context-switch time is pure overhead, because the system does no useful work while switching.
Its speed varies from machine to machine, depending on the memory speed, the number of registers which must be copied, the existed of special instructions such as a single instruction to load or store all registers.
Distributed Systems? Distribute the computation among several physical processors. Difference between Primary storage and secondary storage? Main memory: — only large storage media that the CPU can access directly. Secondary storage: — extension of main memory that provides large nonvolatile storage capacity.
What is CPU Scheduler? Selects from among the processes in memory that are ready to execute, and allocates the CPU to one of them. CPU scheduling decisions may take place when a process: 1. Switches from running to waiting state. Switches from running to ready state. Switches from waiting to ready. Scheduling under 1 and 4 is nonpreemptive.
All other scheduling is preemptive. What do you mean by deadlock? Deadlock is a situation where a group of processes are all blocked and none of them can become unblocked until one of the other becomes unblocked.
The simplest deadlock is two processes each of which is waiting for a message from the other What is Dispatcher? What is Throughput, Turnaround time, waiting time and Response time? Throughput — number of processes that complete their execution per time unit Turnaround time — amount of time to execute a particular process Waiting time — amount of time a process has been waiting in the ready queue Response time — amount of time it takes from when a request was submitted until the first response is produced, not output for time-sharing environment Explain the difference between microkernel and macro kernel?
Micro-Kernel: A micro-kernel is a minimal operating system that performs only the essential functions of an operating system. All other operating system functions are performed by system processes.
Monolithic: A monolithic operating system is one where all operating system code is in a single executable image and all operating system code runs in system mode. What is multi tasking, multi programming, multi threading? Multi programming: Multiprogramming is the technique of running several programs at a time using timesharing. It allows a computer to do several things at the same time. Multiprogramming creates logical parallelism.
The concept of multiprogramming is that the operating system keeps several jobs in memory simultaneously. Because threads have some of the properties of processes, they are sometimes called lightweight processes. Threads are popular way to improve application through parallelism.
For example, in a browser, multiple tabs can be different threads.
MS word uses multiple threads, one thread to format the text, other thread to process inputs, etc. A thread has its own program counter PC , a register set, and a stack space.
Threads are not independent of one other like processes as a result threads shares with other threads their code section, data section and OS resources like open files and signals. What is deadlock? Deadlock is a situation when two or more processes wait for each other to finish and none of them ever finish.
Consider an example when two trains are coming toward each other on same track and there is only one track, none of the trains can move once they are in front of each other. Similar situation occurs in operating systems when there are two or more processes hold some resources and wait for resources held by other s. What are the necessary conditions for deadlock?
Mutual Exclusion: There is a resource that cannot be shared. No Preemption: The operating system is not allowed to take a resource back from a process until process gives it back. What is Virtual Memory? How is it implemented? Virtual memory creates an illusion that each user has one or more contiguous address spaces, each beginning at address zero. The sizes of such virtual address spaces is generally very high.
The idea of virtual memory is to use disk space to extend the RAM. The illusion of such a large amount of memory is created by subdividing the virtual memory into smaller pieces, which can be loaded into physical memory whenever they are needed by a process.
What is Thrashing?