Windows Interview Questions

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...

Give a non-computer example of preemptive and non-preemptive scheduling?

Consider   any system where people use some kind of resources and compete for them. The non-computer examples for preemptive scheduling the traffic on the single lane road if there is emergency or there is an ambulance on the road the other vehicles give path to the vehicles that are in need....

What are the difference phases of software development or software life cycle?Ans specification of the taskdesign of algorithmsimplementation (coding)testing and debuggingmaintenance and evolution of the...

Different types of real-time scheduling?

Hard real-time systems – required to complete a critical task within a guaranteed amount of time.Soft real-time computing – requires that critical processes receive priority over less fortunate ones.

What are dump terminals in UNIX?

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...

Describe the actions taken by thread library to context switch between user level threads?

The thread library function performs the following actions to context switch between user level threadscopy all live registers to thread control block (tcb)restore the state of the thread to run next i.E (copy the values of live registers from (tcb) to registers)move to the next thread to execute

Compare LINUX credit based algorithm with other scheduling algorithms?

For the conventional time –shared processes, LINUX uses a prioritized, credit-based algorithm. Each process possesses a certain number of scheduling credits; when a new task must be chosen to run, the process with most credits is selected. Every time that a timer interrupt occurs, the currently running...

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...

What is hard disk and what is its purpose?

Hard disk is the secondary storage device, which holds the data in bulk, and it holds the data on the magnetic medium of the disk.Hard disks have a hard platter that holds the magnetic medium, the magnetic medium can be easily erased and rewritten, and a typical desktop machine will have a hard disk...

What are the methods for handling deadlocks?

->ensure that the system will never enter a deadlock state.->allow the system to enter a deadlock state and then recover.->ignore the problem and pretend that deadlocks never occur in the system; used by most operating systems, including   UNIX.

What is a safe state and its’ use in deadlock avoidance?

When a process requests an available resource, system must decide if immediate allocation leaves the system in a    safe state->system is in safe state if there exists a safe sequence of all processes.  ->sequence <p1, p2… pn> is safe if for each pi, the resources that...

Recovery from deadlock?

Process termination:->abort all deadlocked processes.->abort one process at a time until the deadlock cycle is eliminated.->in which order should we choose to abort?Priority of the process.How long process has computed, and how much longer to completion.Resources the process has used. Resources...

Binding of instructions and data to memory?

Address binding of instructions and data to memory addresses can happen at three different stagescompile time:  if memory location known a priori, absolute code can be generated; must recompile code if starting   location changes.Load time:  must generate relocatable code if memory...

What are dynamic loading, dynamic linking and overlays?

Dynamic loading:->routine is not loaded until it is called->better memory-space utilization; unused routine is never loaded.->useful when large amounts of code are needed to handle infrequently occurring cases.->no special support from the operating system is required implemented through...

What are the different dynamic storage-allocation methods?

How to satisfy a request of size n from a list of free holes?First-fit:  allocate the first hole that is big enough.Best-fit:  allocate the smallest hole that is big enough; must search entire list, unless ordered by size. It produces the smallest lEFTover hole.Worst-fit:  allocate the...

What is fragmentation? Different types of fragmentation?

Fragmentation occurs in a dynamic memory allocation system when many of the free blocks are too small to satisfy any request. external fragmentation: external fragmentation happens when a dynamic memory allocation algorithm allocates some memory and a small piece is lEFT over that cannot be effectively...

Explain segmentation with paging?

Segments can be of different lengths, so it is harder to find a place for a segment in memory than a page. With segmented virtual memory, we get the benefits of virtual memory but we still have to do dynamic storage allocation of physical memory. In order to avoid this, it is possible to combine segmentation...

Under what circumstances do page faults occur? Describe the actions taken by the operating system when a page fault occurs?

 a page fault occurs when an access to a page that has not been brought into main memory takes place. The operating system verifies the memory access, aborting the program if it is invalid. If it is valid, a free frame is located and i/o is requested to read the needed page into the free frame....

What is the cause of thrashing? How does the system detect thrashing? Once it detects thrashing, what can the system do to eliminate this problem?

Thrashing is caused by under allocation of the minimum number of pages required by a process, forcing it to continuously page fault. The system can detect thrashing by evaluating the level of cpu utilization as compared to the level of multiprogramming. It can be eliminated by reducing the level of...