MCS-041 December 2018

If you have any queries please leave a message here
Your Message
×


1. (a) What is a deadlock ? Explain the necessary and sufficient conditions for deadlock occurrence. Also explain how deadlock can be prevented.

Answer : - Deadlock is a situation where a set of processes are blocked because each process is holding a resource and waiting for another resource acquired by some other process.

Conditions for Deadlock Occurrence

Coffman stated four conditions for a deadlock occurrence. A deadlock may occur if all the following conditions holds true.


Deadlock Prevention

We have learnt that if all the four Coffman conditions hold true then a deadlock occurs so preventing one or more of them could prevent the deadlock.




1. (b) What is mutual exclusion ? Write and explain Dekker's solution for mutual exclusion.

Answer : - Mutual Exclusion is a concurrency control property which is introduced to prevent race conditions. It is the requirement that a process can not enter its critical section while another concurrent process is currently present or executing in its critical section i.e only one process is allowed to execute the critical section at any given instance of time.




1. (c) Explain with a diagram, how paging supports the virtual memory. Also explain how a logical address is translated into a physical address in paging.

Answer : -


1. (d) Write and explain Lamport's Bakery Algorithm with an example in a distributed OS.

Answer : -


2. (a) Differentiate between a process and a - thread. Draw and explain the five states process model.

Answer : -

Difference between Process and Thread


Process Life Cycle

When a process executes, it passes through different states. The various states of the process are as followings -

NewThis is the initial state when a process is first started/created.
ReadyAfter the creation of a process, the process enters the ready state i.e. the process is loaded into the main memory. The process here is ready to run and is waiting to get the CPU time for its execution. Processes that are ready for execution by the CPU are maintained in a queue for ready processes.
RunningOnce the process has been assigned to a processor by the OS scheduler, the process state is set to running and the processor executes its instructions.
WaitingProcess moves into the waiting state if it needs to wait for a resource, such as waiting for user input, or waiting for a file to become available. Once the Input/Output operation is completed the process goes to the ready state.
Terminated or ExitOnce the process finishes its execution, or it is terminated by the operating system, it is moved to the terminated state where it waits to be removed from main memory.




2. (b) Give the components of UNIX system. Describe the role of kernel in UNIX.

Answer : - UNIX is a multi-user, multi-tasking operating system. Multiple users may have multiple tasks running simultaneously. This is very different from other operating systems such as MS-Windows (which allows multiple tasks to be carried out simultaneously but not multiple users).

Unix is made up of three components :

Kernel


Functions performed by the kernel are :




3. (a) Explain FCFS, LRU, Optimal page replacement algorithms. Which algorithm suffers from Belady's anomaly ? Explain with an example.

Answer : -


3. (b) Write short notes on the following :

Explain with suitable diagrams.

Answer : -

Overlays

The main problem in Fixed partitioning is the size of a process has to be limited by the maximum size of the partition, which means a process can never be span over another. In order to solve this problem, earlier people have used some solution which is called as Overlays.

The concept of overlays is that whenever a process is running it will not use the complete program at the same time, it will use only some part of it. Then overlays concept says that whatever part you required, you load it and once the part is done, then you just unload it, means just pull it back and get the new part you required and run it.


Swapping

Swapping is a mechanism in which a process can be swapped temporarily out of main memory (or move) to secondary storage (disk) and make that memory available to other processes. At some later time, the system swaps back the process from the secondary storage to main memory.

Though performance is usually affected by swapping process but it helps in running multiple and big processes in parallel and that's the reason Swapping is also known as a technique for memory compaction.

Swaping Image




4. (a) Discuss various design issues involved in a distributed system

Answer : -

Heterogeneity - The Internet enables users to access services and run applications over a heterogeneous collection of computers and networks. Heterogeneity (that is, variety and difference) applies to all of the following :

Different programming languages use different representations for characters and data structures such as arrays and records. These differences must be addressed if programs written in different languages are to be able to communicate with one another. Programs written by different developers cannot communicate with one another unless they use common standards.


Openness - The openness of a computer system is the characteristic that determines whether the system can be extended and re-implemented in various ways. The openness of distributed systems is determined primarily by the degree to which new resource-sharing services can be added and be made available for use by a variety of client programs.


Scalability - Distributed systems must be scalable as the number of user increases. The scalability is defined by B. Clifford Neuman as "A system is said to be scalable if it can handle the addition of users and resources without suffering a noticeable loss of performance or increase in administrative complexity"

Scalability has 3 dimensions :


Failure Handling - When faults occur in hardware or software program, it may produce incorrect results or may stop before they have completed the intended computation. Failures in a distributed system are partial – that is, some components fail while others continue to function. Therefore the handling of failures is particularly difficult.


Security - Many of the information resources that are made available and maintained in distributed systems have a high intrinsic value to their users. Their security is therefore of considerable importance. Security for information resources has three components:


Concurrency - Both services and applications provide resources that can be shared by clients in a distributed system. There is therefore a possibility that several clients will attempt to access a shared resource at the same time. Object that represents a shared resource in a distributed system must be responsible for ensuring that it operates correctly in a concurrent environment. This applies not only to servers but also to objects in applications. Therefore any programmer who takes an implementation of an object that was not intended for use in a distributed system must do whatever is necessary to make it safe in a concurrent environment.


Transparency - Transparency is defined as the concealment from the user and the application programmer of the separation of components in a distributed system, so that the system is perceived as a whole rather than as a collection of independent components. In other words, distributed systems designers must hide the complexity of the systems as much as they can.




4. (b) With the help of a neat diagram, describe Crossbar and Hypercube multiprocessor interconnection architecture.

Answer : - Multiprocessor system is an interconnection of two or more CPUs, each sharing main memory and peripherals, in order to simultaneously process programs.

Multiprocessing improves the rellability of the system, which means if a fault causes one processor to fail, a second processor can be assigned to perform the function of the disabled processor. Thus, a system can continue to function correctly.


Crossbar Multiprocessor Interconnection Architecture


Hypercube Multiprocessor Interconnection Architecture




5. Write short notes on the following :

(a) Virtual Memory System

Answer : - Virtual Memory


(b) Take-Grant Security Model

Answer : - The Take-Grant System is a model that helps in determining the protection rights (e.g., read or write) in a computer system. The Take-Grant system was introduced by Jones, Lipton, and Snyder to show that it is possible to decide on the safety of a computer system even when the number of subjects and objects are very large, or unbound. This can be accomplished in linear time based on the initial size of the system.

The take-grant system models a protection system which consists of a set of states and state transitions. A directed graph shows the connections between the nodes of this system. These nodes are representative of the subjects or objects of the model. The directed edges between the nodes represent the rights that one node has over the linked node.

There are a total of four such rules :


(c) Paging in Memory Management

Answer : - Paging in Memory Management


(d) Memory Management in Windows 2000

Answer : -





ABOUT US

QuestionSolves.com is an educational website that helps worldwide students in solving computer education related queries.

Also, different software like Visual Studio, SQL Server, Oracle etc. are available to download in different versions.

Moreover, QuestionSolves.com provides solutions to your questions and assignments also.


MORE TOPIC


Windows Command

UNIX Command

IGNOU Assignment Solution

IGNOU Question Paper Solution

Solutions of Different Questions


WHAT WE DO


Website Devlopment

Training

Home Learning

Provide BCA, MCA Projects

Provide Assignment & Question Paper Solution


CONTACT US


Follow Us