2023 105403

End Semester Examination - 2023

Time 03 Hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are NINE questions in this paper.
Attempt FIVE questions in all.
Question No. 1 is compulsory.

Q.1 Answer any seven question of the following:

Q1.1

A computer system has 9 tape drives, with $ n $ processes competing for them. Each process may need 3 tape drives. The maximum value of $ n $ for which the system is guaranteed to be deadlock free is

a)

9

b)

7

c)

8

d)

6

Q1.2

Which of the following page replacement algorithms suffers from Belady's anomaly?

a)

Optimal replacement

b)

LRU

c)

FIFO

d)

Both (a) and (c)

Q1.3

Scheduling a process from ready Queue to CPU is done by

a)

Short term scheduler

b)

Middle term scheduler

c)

Long term scheduler

d)

Dispatcher

Q1.4

The time to move the disk arm to the desired cylinder in hard disk is known as

a)

rotational latency

b)

seek time

c)

positional time

d)

disk time

Q1.5

Compaction is used to solve the problem of

a)

external fragmentation

b)

internal fragmentation

c)

both (a) and (c)

d)

None of these

Q1.6

__________ is a technique of improving the priority of process waiting in queue for CPU allocation.

a)

Starvation

b)

Ageing

c)

Revocation

d)

Relocation

Q1.7

The CPU utilization is low when the system is

a)

timesharing

b)

thrashing

c)

multiprocessing

d)

None of the above

Q1.8

When a process waits indefinitely for some resources which are being used by other processes, it is called

a)

Starvation

b)

Demand Paging

c)

Segmentation

d)

None of the above

Q1.9

Fork is used to

a)

dispatch a task

b)

create a new job

c)

create a new process

d)

increase the priority of a task

Q1.10

Which one of the following is the deadlock avoidance algorithm?

a)

Banker's algorithm

b)

Round-robin algorithm

c)

Elevator algorithm

d)

Karn's algorithm

Q.2 Solve both questions :

Q2.1

Explain the concept of a process. With the help of a state transition diagram, discuss the various process states.

Q2.2

Describe the differences among short term, medium-term, and long-term scheduling.

Q.3 Solve both questions :

Q3.1

What are the various allocation policies in variable partition multiprogramming? Explain the differences between internal and external fragmentations.

Q3.2

What do you understand by address binding? Explain the various address binding schemes.

Q.4 Solve all questions :

Q4.1

What are the differences between user-level threads and kernel-level threads? Under what circumstances is one type better than the other?

Q4.2

What resources are used when a thread is created? How do they differ from those used when a process is created?

Q4.3

Describe the actions taken by a kernel to context switch between kernel-level threads.

Q.5 Solve both questions :

Q5.1

What do you understand by deadlock? Discuss the methods to avoid deadlock.

Q5.2

State and explain the necessary and sufficient conditions for a deadlock.

Q.6 Solve this question :

Q6.1

Consider the following process with the given table:

Process	Arrival Time	Burst Time
P1	0.0	7
P2	2.0	4
P3	4.0	1
P4	5.0	4

Considering non-preemptive and preemptive SJF algorithm, find out average waiting time and average turnaround time in both cases.

Q.7 Solve both questions :

Q7.1

What do you mean by critical section problem? Discuss Peterson's solution for critical section problem.

Q7.2

Consider the following page reference string :
7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1
How many page faults would occur for the following replacement algorithms? Assuming 3 frames are available. Also assume that initially none of pages in main memory.
(i) Optimal replacement
(ii) FIFO replacement

Q.8 Solve both questions :

Q8.1

Suppose a disk drive has 300 cylinders, numbered 0 to 299. The current head position of the disk is at 90. The queue of pending requests, in FIFO order is 36, 79, 15, 120, 199, 270, 89, 170. Calculate the average cylinder movements for Shortest-Seek Time First (SSTF) algorithm. Mention the disadvantages of SSTF.

Q8.2

Compare and contrast between linked and indexed disk allocation strategies.

Q.9 Write short notes on any two of the following:

Q9.1

I-node

Q9.2

Segmentation

Q9.3

Thrashing

Q9.4

Process Control Block

2023 V4 105403

End Semester Examination - 2023

Time 03 Hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are NINE questions in this paper.
Attempt FIVE questions in all.
Question No. 1 is compulsory.

Q.1 Answer any seven question of the following:

Q1.1

A computer system has 9 tape drives, with $ n $ processes competing for them. Each process may need 3 tape drives. The maximum value of $ n $ for which the system is guaranteed to be deadlock free is

a)

9

b)

7

c)

8

d)

6

Q1.2

Which of the following page replacement algorithms suffers from Belady's anomaly?

a)

Optimal replacement

b)

LRU

c)

FIFO

d)

Both (a) and (c)

Q1.3

Scheduling a process from ready Queue to CPU is done by

a)

Short term scheduler

b)

Middle term scheduler

c)

Long term scheduler

d)

Dispatcher

Q1.4

The time to move the disk arm to the desired cylinder in hard disk is known as

a)

rotational latency

b)

seek time

c)

positional time

d)

disk time

Q1.5

Compaction is used to solve the problem of

a)

external fragmentation

b)

internal fragmentation

c)

both (a) and (c)

d)

None of these

Q1.6

__________ is a technique of improving the priority of process waiting in queue for CPU allocation.

a)

Starvation

b)

Ageing

c)

Revocation

d)

Relocation

Q1.7

The CPU utilization is low when the system is

a)

timesharing

b)

thrashing

c)

multiprocessing

d)

None of the above

Q1.8

When a process waits indefinitely for some resources which are being used by other processes, it is called

a)

Starvation

b)

Demand Paging

c)

Segmentation

d)

None of the above

Q1.9

Fork is used to

a)

dispatch a task

b)

create a new job

c)

create a new process

d)

increase the priority of a task

Q1.10

Which one of the following is the deadlock avoidance algorithm?

a)

Banker's algorithm

b)

Round-robin algorithm

c)

Elevator algorithm

d)

Karn's algorithm

Q.2 Solve both questions :

Q2.1

Explain the concept of a process. With the help of a state transition diagram, discuss the various process states.

Q2.2

Describe the differences among short term, medium-term, and long-term scheduling.

Q.3 Solve both questions :

Q3.1

What are the various allocation policies in variable partition multiprogramming? Explain the differences between internal and external fragmentations.

Q3.2

What do you understand by address binding? Explain the various address binding schemes.

Q.4 Solve all questions :

Q4.1

What are the differences between user-level threads and kernel-level threads? Under what circumstances is one type better than the other?

Q4.2

What resources are used when a thread is created? How do they differ from those used when a process is created?

Q4.3

Describe the actions taken by a kernel to context switch between kernel-level threads.

Q.5 Solve both questions :

Q5.1

What do you understand by deadlock? Discuss the methods to avoid deadlock.

Q5.2

State and explain the necessary and sufficient conditions for a deadlock.

Q.6 Solve this question :

Q6.1

Consider the following process with the given table:

Process	Arrival Time	Burst Time
P1	0.0	7
P2	2.0	4
P3	4.0	1
P4	5.0	4

Considering non-preemptive and preemptive SJF algorithm, find out average waiting time and average turnaround time in both cases.

Q.7 Solve both questions :

Q7.1

What do you mean by critical section problem? Discuss Peterson's solution for critical section problem.

Q7.2

Consider the following page reference string :
7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1
How many page faults would occur for the following replacement algorithms? Assuming 3 frames are available. Also assume that initially none of pages in main memory.
(i) Optimal replacement
(ii) FIFO replacement

Q.8 Solve both questions :

Q8.1

Suppose a disk drive has 300 cylinders, numbered 0 to 299. The current head position of the disk is at 90. The queue of pending requests, in FIFO order is 36, 79, 15, 120, 199, 270, 89, 170. Calculate the average cylinder movements for Shortest-Seek Time First (SSTF) algorithm. Mention the disadvantages of SSTF.

Q8.2

Compare and contrast between linked and indexed disk allocation strategies.

Q.9 Write short notes on any two of the following:

Q9.1

I-node

Q9.2

Segmentation

Q9.3

Thrashing

Q9.4

Process Control Block

2022 105403

B.Tech 4th Semester Exam., 2022

Time 3 hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are NINE questions in this paper.
Attempt FIVE questions in all.
Question No. 1 is compulsory.

Q.1 Answer/Choose the correct answer of the following (any seven):

Q1.1

What is the difference between a multiprocessor and a multicore system?

Q1.2

What is multiprogramming?

Q1.3

Define jacketing.

Q1.4

What operations can be performed on a semaphore?

Q1.5

What is the difference between a page and a frame?

Q1.6

In contiguous memory allocation

a)

each process is contained in a single contiguous section of memory

b)

all processes are contained in a single contiguous section of memory

c)

the memory space is contiguous

d)

None of the above

Q1.7

If the size of logical address space is 2 to the power of $ m $, and a page size is 2 to the power of $ n $ addressing units, then the high order ___ bits of a logical address designate the page number, and the ___ low order bits designate the page offset.

a)

$m, n$

b)

$n, m$

c)

$m-n, m$

d)

$m-n, n$

Q1.8

If the wait for graph contains a cycle, then

a)

a deadlock does not exist

b)

a deadlock exists

c)

the system is in a safe state

d)

either deadlock exists or system is in a safe state

Q1.9

When the event for which a thread is blocked occurs?

a)

Thread moves to the ready queue

b)

Thread remains blocked

c)

Thread completes

d)

A new thread is provided

Q1.10

An I/O port typically consists of four registers status, control, ___ and ___ registers.

a)

system in, system out

b)

data in, data out

c)

flow in, flow out

d)

input, output

Q.2 Solve both questions :

Q2.1

What is the purpose of interrupts? What are the differences between a trap and an interrupt? Can traps be generated intentionally by a user program? If so, for what purpose?

Q2.2

Answer the following with full justifications:
Does swapping improve or degrade the efficiency of system utilization?
Can swapping be used in a multiprogramming system?

Q.3 Solve both questions :

Q3.1

Including the initial parent process, how many processes are created by the program shown below?
#include<stdio.h>
#include<unistd.h>
int main()
{
/* fork a child process */
fork();
/* fork another child process */
fork();
/* and fork another */
fork();
return 0;
}

Q3.2

Describe the differences among short-term, medium-term, and long-term scheduling.

Q.4 Solve both questions :

Q4.1

An airline reservation system, using a centralized database service, user requests concurrently. Is it preferable to use threads rather than processes in this system? Give reasons for your answer.

Q4.2

Consider a system running ten I/O-bound tasks and one CPU-bound task. Assume that the I/O-bound tasks issue an I/O operation once for every millisecond of CPU computing and that each I/O operation takes 10 milliseconds to complete. Also assume that the context-switching overhead is 0.1 millisecond and that all processes are long-running tasks. Describe the CPU utilization for a round-robin scheduler when-
(i) the time quantum is 1 millisecond;
(ii) the time quantum is 10 milliseconds.

Q.5 Solve both questions :

Q5.1

Clearly justify why deadlocks cannot arise in a bounded buffer producers-consumers system.

Q5.2

Consider a system consisting of four resources of the same type that are shared by three processes, each of which needs at most two resources. Show that the system is deadlock-free.

Q.6 Solve this question :

Q6.1

Five batch jobs, A through E, arrive at a computer center at essentially the same time. They have an estimated running time of 15, 9, 3, 6 and 12 minutes, respectively. Their (externally defined) priorities are 6, 3, 1, 4 and 2, respectively, with a lower value corresponding to a higher priority. For each of the following scheduling algorithms, determine the waiting time for each process and the average waiting for all jobs. Ignore process switching overhead. Explain how you arrived at your answers. In the last three cases, assume that only one job at a time runs until it finishes and that all jobs are completely processor bound:
(a) Priority scheduling
(b) FCFS (run in order 15, 9, 3, 6 and 12)
(c) Shortest job first

Q.7 Solve this question :

Q7.1

A bridge on a busy highway is damaged by a flood. One-way traffic is to be instituted on the bridge by permitting vehicles traveling in opposite directions to use the bridge alternately. The following rules are formulated for use of the bridge:
(a) At any time, the bridge is used by vehicle(s) traveling in one direction only.
(b) If vehicles are waiting to cross the bridge at both ends, only one vehicle from one end is allowed to cross the bridge before a vehicle from the other end starts crossing the bridge.
(c) If no vehicles are waiting at one end, then any numbers of vehicles from the other end are permitted to cross the bridge.
Develop a concurrent system to implement these rules.

Q.8 Solve both questions :

Q8.1

Consider a simple paging system with the following parameters:
• $ 232 $ bytes of physical memory
• Page size of $ 210 $ bytes
• $ 216 $ pages of logical address space
(i) How many bits are in a logical address?
(ii) How many bytes are in a frame?
(iii) How many bits in the physical address specify the frame?
(iv) How many entries are in the page table?

Q8.2

Given five memory partitions of 100 KB, 500 KB, 200 KB, 300 KB and 600 KB (in order). How would the first-fit, best-fit, and worst-fit algorithms place processes of 212 KB, 417 KB, 112 KB and 426 KB (in order)? Which algorithm makes the most efficient use of memory?

Q.9 Solve both questions :

Q9.1

Consider a demand paging system with a paging disk that has an average access and transfer time of 20 milliseconds. Addresses are translated through a page table in main memory, with an access time of 1 microsecond. Thus, each memory reference through the page table takes two accesses. To improve this time, we have added an associative memory that reduces access time to one memory reference if the page-table entry is in the associative memory. Assume that 80 percent of the accesses are in the associative memory and that of those remaining 10 percent (or 2 percent of the total) cause page faults. What is the effective memory access time?

Q9.2

The open file table is used to maintain information about files that are currently open. Should the operating system maintain a separate table for each user or just maintain one table that contains references to files that are currently being accessed by all users? If the same file is being accessed by two different programs or users, should there be separate entries in the open-file table?

2022 V4 105403

B.Tech 4th Semester Exam., 2022

Time 3 hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are NINE questions in this paper.
Attempt FIVE questions in all.
Question No. 1 is compulsory.

Q.1 Answer/Choose the correct answer of the following (any seven):

Q1.1

What is the difference between a multiprocessor and a multicore system?

Q1.2

What is multiprogramming?

Q1.3

Define jacketing.

Q1.4

What operations can be performed on a semaphore?

Q1.5

What is the difference between a page and a frame?

Q1.6

In contiguous memory allocation

a)

each process is contained in a single contiguous section of memory

b)

all processes are contained in a single contiguous section of memory

c)

the memory space is contiguous

d)

None of the above

Q1.7

If the size of logical address space is 2 to the power of $ m $, and a page size is 2 to the power of $ n $ addressing units, then the high order ___ bits of a logical address designate the page number, and the ___ low order bits designate the page offset.

a)

$m, n$

b)

$n, m$

c)

$m-n, m$

d)

$m-n, n$

Q1.8

If the wait for graph contains a cycle, then

a)

a deadlock does not exist

b)

a deadlock exists

c)

the system is in a safe state

d)

either deadlock exists or system is in a safe state

Q1.9

When the event for which a thread is blocked occurs?

a)

Thread moves to the ready queue

b)

Thread remains blocked

c)

Thread completes

d)

A new thread is provided

Q1.10

An I/O port typically consists of four registers status, control, ___ and ___ registers.

a)

system in, system out

b)

data in, data out

c)

flow in, flow out

d)

input, output

Q.2 Solve both questions :

Q2.1

What is the purpose of interrupts? What are the differences between a trap and an interrupt? Can traps be generated intentionally by a user program? If so, for what purpose?

Q2.2

Answer the following with full justifications:
Does swapping improve or degrade the efficiency of system utilization?
Can swapping be used in a multiprogramming system?

Q.3 Solve both questions :

Q3.1

Including the initial parent process, how many processes are created by the program shown below?
#include<stdio.h>
#include<unistd.h>
int main()
{
/* fork a child process */
fork();
/* fork another child process */
fork();
/* and fork another */
fork();
return 0;
}

Q3.2

Describe the differences among short-term, medium-term, and long-term scheduling.

Q.4 Solve both questions :

Q4.1

An airline reservation system, using a centralized database service, user requests concurrently. Is it preferable to use threads rather than processes in this system? Give reasons for your answer.

Q4.2

Consider a system running ten I/O-bound tasks and one CPU-bound task. Assume that the I/O-bound tasks issue an I/O operation once for every millisecond of CPU computing and that each I/O operation takes 10 milliseconds to complete. Also assume that the context-switching overhead is 0.1 millisecond and that all processes are long-running tasks. Describe the CPU utilization for a round-robin scheduler when-
(i) the time quantum is 1 millisecond;
(ii) the time quantum is 10 milliseconds.

Q.5 Solve both questions :

Q5.1

Clearly justify why deadlocks cannot arise in a bounded buffer producers-consumers system.

Q5.2

Consider a system consisting of four resources of the same type that are shared by three processes, each of which needs at most two resources. Show that the system is deadlock-free.

Q.6 Solve this question :

Q6.1

Five batch jobs, A through E, arrive at a computer center at essentially the same time. They have an estimated running time of 15, 9, 3, 6 and 12 minutes, respectively. Their (externally defined) priorities are 6, 3, 1, 4 and 2, respectively, with a lower value corresponding to a higher priority. For each of the following scheduling algorithms, determine the waiting time for each process and the average waiting for all jobs. Ignore process switching overhead. Explain how you arrived at your answers. In the last three cases, assume that only one job at a time runs until it finishes and that all jobs are completely processor bound:
(a) Priority scheduling
(b) FCFS (run in order 15, 9, 3, 6 and 12)
(c) Shortest job first

Q.7 Solve this question :

Q7.1

A bridge on a busy highway is damaged by a flood. One-way traffic is to be instituted on the bridge by permitting vehicles traveling in opposite directions to use the bridge alternately. The following rules are formulated for use of the bridge:
(a) At any time, the bridge is used by vehicle(s) traveling in one direction only.
(b) If vehicles are waiting to cross the bridge at both ends, only one vehicle from one end is allowed to cross the bridge before a vehicle from the other end starts crossing the bridge.
(c) If no vehicles are waiting at one end, then any numbers of vehicles from the other end are permitted to cross the bridge.
Develop a concurrent system to implement these rules.

Q.8 Solve both questions :

Q8.1

Consider a simple paging system with the following parameters:
• $ 232 $ bytes of physical memory
• Page size of $ 210 $ bytes
• $ 216 $ pages of logical address space
(i) How many bits are in a logical address?
(ii) How many bytes are in a frame?
(iii) How many bits in the physical address specify the frame?
(iv) How many entries are in the page table?

Q8.2

Given five memory partitions of 100 KB, 500 KB, 200 KB, 300 KB and 600 KB (in order). How would the first-fit, best-fit, and worst-fit algorithms place processes of 212 KB, 417 KB, 112 KB and 426 KB (in order)? Which algorithm makes the most efficient use of memory?

Q.9 Solve both questions :

Q9.1

Consider a demand paging system with a paging disk that has an average access and transfer time of 20 milliseconds. Addresses are translated through a page table in main memory, with an access time of 1 microsecond. Thus, each memory reference through the page table takes two accesses. To improve this time, we have added an associative memory that reduces access time to one memory reference if the page-table entry is in the associative memory. Assume that 80 percent of the accesses are in the associative memory and that of those remaining 10 percent (or 2 percent of the total) cause page faults. What is the effective memory access time?

Q9.2

The open file table is used to maintain information about files that are currently open. Should the operating system maintain a separate table for each user or just maintain one table that contains references to files that are currently being accessed by all users? If the same file is being accessed by two different programs or users, should there be separate entries in the open-file table?

2019 061503

B.Tech 5th Semester Exam., 2019

Time 3 hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are NINE questions in this paper.
Attempt FIVE questions in all.
Question No. 1 is compulsory.

Choose the correct answer from any seven of the following :

Q1.a

What is operating system?

a)

Collection of programs that manages hardware resources

b)

System service provider to the application programs

c)

Interface between user and hardware

d)

All of the above

Q1.g

The processes that are residing in main memory and are ready and waiting to execute are kept on a list called

a)

job queue

b)

ready queue

c)

execution queue

d)

process queue

Q1.h

Which of the following conditions is required for deadlock to be possible?

a)

Mutual exclusion

b)

A process may hold allocated resources while awaiting assignment of other resources

c)

No resource can be forcibly removed from a process holding it

d)

All of the above

Q1.i

Which one of the following is the deadlock avoidance algorithm?

a)

Banker's algorithm

b)

Round-robin algorithm

c)

Elevator algorithm

d)

Karn's algorithm

Q1.j

Physical memory is broken into fixed-sized blocks called

a)

frames

b)

pages

c)

backing store

d)

None of the above

Q.2

Q2

What is process control block? Explain it. Discuss the difference among short-term, medium-term and long-term scheduling.

Q.3

Q3

Consider the following process :

Process	Arrival Time	Burst Time
P1	0.0	7
P2	2.0	4
P3	4.0	1
P4	5.0	4

Considering non-preemptive and preemptive SJF algorithm, find out average waiting time and average turnaround time in both cases.

Q.4

Q4

What do you understand by race condition? Give few example of arising of race condition in concurrent processing.

Q.5

Q5.a

Define semaphore. Give a scheme for implementation of semaphore primitives.

Q5.b

What do you mean by critical section problem? What is the solution to the critical section problem?

Q.6

Q6.a

What is a thread?

Q6.b

How is thread different from a process?

Q6.c

What resources are used when a thread is created?

Q.7

Q7

How many page faults would occur for the following reference string for four page frames and three page frames using LRU and FIFO algorithms :

1, 2, 3, 4, 5, 5, 3, 4, 1, 6, 7, 8, 7, 8, 9, 7, 8, 9, 5, 4, 5, 4, 2.

Q.8

Q8

Define deadlock. List four necessary conditions for occurrence of deadlock. A system contains six units of resource, and $n$ processes that use the resource. What is the maximum value of $n$ for which the system will be deadlock free if the maximum requirement of each process is 3?

Q.9

Q9

Explain shortest-seek-time-first (SSTF) disk scheduling. Why SSTF scheduling tends to favour middle cylinders over the innermost and outermost cylinders?

2018 061503

B.Tech Examination, 2018

Time 3 hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are NINE questions in this paper.
Attempt FIVE questions in all.
Question No. 1 is compulsory.

Questions

Q1

Choose the correct option (any seven) :

a)

In which type of operating system, the response time is very crucial?

a)

Unix operating system

b)

Real-time operating system

c)

Network operating system

d)

Batch operating system

b)

A process is

a)

a program in high-level language kept on disk

b)

a contents of main memory

c)

a program in execution

d)

a job in secondary memory

c)

The strategy of temporarily suspending a process that is logically runnable is called

a)

preemptive scheduling

b)

non-preemptive scheduling

c)

shortest job first

d)

first come, first serve

d)

To avoid the race condition, the number of processes that may be simultaneously inside their critical section is

a)

8

b)

1

c)

2

d)

4

e)

Fork is used to

a)

dispatch a task

b)

create a new job

c)

create a new process

d)

increase the priority of a task

f)

The principle of locality of reference justifies the use of

a)

secondary memory

b)

critical section

c)

virtual memory

d)

cache memory

g)

The memory allocation scheme subject to "external" fragmentation is

a)

segmentation

b)

swapping

c)

pure demand paging

d)

multiple continuous fixed partition

h)

The piece of code that only one thread should execute at a time is called

a)

mutual exclusion

b)

critical section

c)

synchronization

d)

None of the above

i)

Which memory allocation policy allocates the largest hole to the process?

a)

Best fit

b)

Worst fit

c)

First fit

d)

None of the above

j)

When there is enough memory to fit a process in memory, but the space is not continuous, then which of the following is required?

a)

Internal fragmentation

b)

Virtual fragmentation

c)

External fragmentation

d)

None of the above

Q2

Answer the following:

a)

What is an operating system? Enumerate the basic functions of the operating system and explain each in brief.

b)

What is meant by process control block? Explain the different fields of PCB with the help of a diagram. Discuss the concept Context Switch by giving an example.

Q3

Answer the following:

a)

Explain the following scheduling algorithms with the help of an example: (i) SJF (ii) Round robin

b)

Differentiate between preemptive scheduling and non-preemptive scheduling.

Q4

Answer the following:

a)

What is meant by deadlock? Explain with example. Elaborate upon the conditions necessary for a deadlock situation to arise.

b)

Discuss the various mechanisms for deadlock recovery.

Q5

Answer the following:

a)

Illustrate the concept of demand paging with the help of a diagram.

b)

What are the various memory allocation schemes?

Q6

Answer the following:

a)

Consider the following reference string: 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1 Calculate the number of page faults that would occur for the following page replacement algorithms with frame size of 4: (i) FIFO (ii) LRU

b)

Explain the concept of semaphores with the help of an example.

Q7

Answer the following:

a)

Discuss the performance criteria of CPU scheduling.

b)

Compare and contrast between linked and indexed disk allocation strategies.

Q8

Answer the following:

a)

Illustrate with examples the following disk scheduling algorithms: (i) SSTF (ii) C-Look

b)

Explain the memory hierarchy of the operating system.

Q9

Write short notes on the following :

a)

Segmentation

b)

Real-time systems

c)

Critical section

2017 061503

B.Tech Examination, 2017

Time 3 hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are NINE questions in this paper.
Attempt FIVE questions in all.
Question No. 1 is compulsory.

Questions

Q1

Choose the correct answer (any seven) :

a)

The operating system manages

a)

memory

b)

processes

c)

disks and I/O devices

d)

All of the above

b)

When a computer is turned on or restarted, a special type of absolute loader called _______ is executed.

a)

compile and go loader

b)

boot loader

c)

bootstrap loader

d)

relating loader

c)

In which type of operating systems, the response time is very crucial?

a)

Unix Operating System

b)

Real-time Operating System

c)

Batch Operating System

d)

Network Operating System

d)

Bringing a page into the memory only when it is needed is called

a)

deadlock

b)

page fault

c)

dormant paging

d)

demand paging

e)

A page fault occurs when

a)

deadlock happens

b)

segmentation starts

c)

page is found in the memory

d)

page is not found in the memory

f)

A program in execution is called

a)

paging

b)

process

c)

virtual memory

d)

demand page

g)

Copying a process from memory to disk to allow space for other processes is called

a)

swapping

b)

deadlock

c)

demand paging

d)

page fault

h)

What does Belady's anomaly relate to?

a)

Page Replacement Algorithm

b)

Memory Management Algorithm

c)

Deadlock Prevention Algorithm

d)

Disk Scheduling Algorithm

i)

The piece of code that only one thread should execute at a time is called

a)

mutual exclusion

b)

critical section

c)

synchronization

d)

None of the above

j)

When a process waits indefinitely for some resources which are being used by other processes, it is called

a)

Starvation

b)

Demand Paging

c)

Segmentation

d)

None of the above

Q2

Answer the following:

a)

Explain the layered structure of an operating system with the help of a diagram. Discuss the various functions performed by the operating system.

b)

Explain the concept of a process. With the help of a state transition diagram, discuss the various process states.

Q3

Consider the following set of processes with the length of CPU burst time in milliseconds : Process | Burst Time (ms) | Priority P1 | 10 | 3 P2 | 1 | 1 P3 | 2 | 3 P4 | 1 | 4 P5 | 5 | 2 The processes are assumed to have arrived in the order P1, P2, P3, P4, P5 and all at time 0.

a)

Draw Gantt chart, illustrating the execution of these processes using FCFS, SJF, and Round Robin (quantum = 1) scheduling.

b)

What is turnaround time of each process for each of the above scheduling algorithms in part (a)?

c)

What is the waiting time for each process for each of the scheduling algorithms in part (a)?

d)

Which of the schedules in part (a) results in the overall minimal average waiting time?

Q4

Answer the following:

a)

Explain the critical section problem with the help of an example. Discuss the requirements that need to be satisfied for a solution of the critical section problem.

b)

Elaborate upon the conditions necessary for a deadlock situation to arise.

Q5

Answer the following:

a)

With the help of a labelled diagram, explain how logical address is translated into physical address using paging mechanism.

b)

What are the various memory allocation schemes?

Q6

Answer the following:

a)

Discuss with examples the following page replacement algorithms : (i) FIFO (ii) LRU

b)

Differentiate between external and internal fragmentations.

Q7

Answer the following:

a)

Explain the usage of Resource Allocation Graph for Deadlock Avoidance.

b)

What is meant by directory? Briefly discuss the various structures of a directory.

Q8

Suppose that a disk drive has 5000 cylinders, numbered 0 to 4999. The drive is currently serving a request at cylinder 143, and the previous request was at cylinder 125. The queue of pending requests, in FIFO order, is : 86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130 Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests for each of the following disk-scheduling algorithms?

a)

FCFS

b)

SSTF

c)

SCAN

Q9

Answer the following:

a)

Process control block

b)

Schedulers

c)

Semaphores

2014 061503

B.Tech Examination, 2014

Time 3 hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are NINE questions in this paper.
Attempt FIVE questions in all.
Question No. 1 is compulsory.

Questions

Q1

Choose the correct answer (any seven) :

a)

Which of the following is a real-time system?

a)

On-line railway reservation system

b)

Process control system

c)

Aircraft control system

d)

Payroll processing system

b)

A process is a

a)

program in high-level language kept on disk

b)

content of main memory

c)

program in execution

d)

job in secondary memory

c)

The strategy of allowing processes that are logically runnable to be temporarily suspended is

a)

preemptive scheduling

b)

non-preemptive scheduling

c)

shortest job first

d)

first come first served

d)

_______ is a technique of improving the priority of process waiting in queue for CPU allocation.

a)

Starvation

b)

Ageing

c)

Revocation

d)

Relocation

e)

Dijkstra's banker algorithm is an operating system to solve the problem of

a)

deadlock avoidance

b)

deadlock recovery

c)

mutual exclusion

d)

context sustaining

f)

Interval between the time of submission and first response to the job is called

a)

waiting time

b)

turnaround time

c)

throughput

d)

response time

g)

Virtual memory can be implemented with

a)

segmentation

b)

paging

c)

Both of the above

d)

None of the above

h)

In which of the following page replacement policies Balady's anomaly occurs?

a)

FIFO

b)

LRU

c)

LFU

d)

NRU

i)

Which of the following approaches does not require knowledge of the system state?

a)

Deadlock detection

b)

Deadlock prevention

c)

Deadlock avoidance

d)

None of the above

j)

Memory management scheme having no internal fragmentation is called

a)

paging

b)

segmentation

c)

Both of the above

d)

None of the above

Q2

Answer the following:

a)

Explain the important properties of the following operating systems : (i) Real-time systems (ii) Time-sharing systems

b)

What is an interrupt? Describe the basic interrupt mechanism.

Q3

Answer the following:

a)

How is a process different from a program? Explain the process state transition with the help of a diagram.

b)

What is a thread? Explain the benefits of using threads.

Q4

Answer the following:

a)

Justify the statement "Operating System works like a resource manager" with an example.

b)

Explain the concept of implementing interprocess communication through shared memory mechanism using suitable example.

Q5

Answer the following:

a)

Explain the concept of critical section with suitable example.

b)

Explain the importance of semaphores.

Q6

Answer the following:

a)

Explain the importance of resource allocation graph.

b)

Explain Banker's algorithm.

Q7

Answer the following:

a)

Differentiate between a file and a directory. Justify for the need of file system.

b)

Explain the main features of general-graph directory structure.

Q8

Answer the following:

a)

Differentiate between preemptive and non-preemptive scheduling.

b)

Consider the following memory references from a 460-word program : 10, 11, 104, 170, 73, 309, 185, 245, 246, 434, 450, 364 (i) Give the reference string assuming page size of 100 words. (ii) Find the number of page faults using the LRU algorithm for a memory of 3 frames.

Q9

Answer the following:

a)

What do you understand by demand paging? Explain the steps in handling a page fault.

b)

How is segmentation different from paging?

2013 061503

B.Tech 5th Semester Exam., 2013

Time 3 hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are NINE questions in this paper.
Attempt FIVE questions in all.
Question No. 1 is compulsory.

Choose the correct option (any seven) :

Q1.a

An operating system is a type of —— software.

a)

application

b)

system

c)

utility

d)

All of the above

Q1.b

A process is

a)

a program in high-level language kept on disk

b)

contents of main memory

c)

a program in execution

d)

a job in secondary memory

Q1.c

An operating system having rigid time requirements is known as

a)

batch processing system

b)

multiprogramming system

c)

real-time system

d)

multitasking system

Q1.d

—— is a technique of improving the priority of process waiting in queue for CPU allocation.

a)

Starvation

b)

Ageing

c)

Revocation

d)

Relocation

Q1.e

Kernel mode of operation is also called

a)

supervisor mode

b)

privileged mode

c)

Both

d)

None of the above

Q1.f

Interval between the time of submission and completion of the job is called

a)

waiting time

b)

turnaround time

c)

throughput

d)

response time

Q1.g

A software generated interrupt is called

a)

trap

b)

software interrupt

c)

soft interrupt

d)

hard interrupt

Q1.h

In which of the following page replacement policies Belady's anomaly occurs?

a)

FIFO

b)

LRU

c)

LFU

d)

NRU

Q1.i

LRU page replacement algorithm stands for

a)

Last Recently Used algorithm

b)

Least Recently Used algorithm

c)

Latest Recently Used algorithm

d)

Lowest Recently Used algorithm

Q1.j

Memory management scheme having no external fragmentation is called

a)

paging

b)

segmentation

c)

Both

d)

None of the above

Q.2

Q2.a

Explain the duties of operating system.

Q2.b

How is a process different from a program? Explain the importance and need for process control block.

Q.3

Q3.a

Explain the use of resource allocation graph.

Q3.b

What is thread? Explain the benefits of using thread.

Q.4

Q4.a

What do you understand by deadlock? Discuss the methods to avoid deadlock.

Q4.b

What is thrashing? How can it be controlled?

Q.5

Q5.a

Explain the various address binding schemes.

Q5.b

Explain the segmentation technique with the help of a diagram.

Q.6

Q6.a

Explain the following terms :
(i) Turnaround time
(ii) Waiting time
(iii) Response time
(iv) Throughput

Q6.b

Consider the following page replacement string :
0, 7, 1, 2, 0, 3, 7, 4, 2, 3, 0, 3, 2, 1, 0, 7, 1, 7, 0, 1
Find the number of page faults using the following algorithms for a memory of 4 frames :
(i) FIFO algorithm
(ii) Optimal algorithm

Q.7

Q7.a

Explain the use of TLB in paging hardware and its benefits.

Q7.b

Explain the role of different types of scheduler.

Q.8

Q8.a

What is Belady's anomaly? Explain the steps for page replacement.

Q8.b

Explain the options for allocation of frames among various processes.

Q.9

Q9.a

Explain the working of LOOK and C-LOOK scheduling algorithms.

Q9.b

Explain Dining-Philosophers problem.

2013 105314

Examination 2013

Time 3 hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are TEN questions in this paper.
Attempt any FIVE questions.

Q.1 Solve all questions :

Q1.1

Define operating system. What are the duties performed by an operating system?

Q1.2

What are the main advantages of time sharing systems?

Q1.3

What are system calls? Explain their importance.

Q.2 Solve both questions :

Q2.1

Differentiate between a file and a Directory. Justify for the need of file system.

Q2.2

Explain the main features of general graph directory structure.

Q.3 Solve both questions :

Q3.1

What do you understand by deadlock? Discuss the methods to avoid deadlock in an operating system.

Q3.2

Explain the working of resource allocation graph.

Q.4 Solve both questions :

Q4.1

What is the difference between physical and logical address space?

Q4.2

What are semaphores? How can they be used to handle the process synchronization problem?

Q.5 Solve both questions :

Q5.1

What are the benefits of segmentation?

Q5.2

Explain the segmentation technique with the help of a diagram.

Q.6 Solve both questions :

Q6.1

Explain the following terms:
(i) Turnaround time
(ii) Waiting time
(iii) Response time
(iv) Throughput

Q6.2

Consider the following page replacement string: 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1
Find the number of page faults using the following algorithms for a memory of three frames:
(i) FIFO algorithm
(ii) LRU algorithm

Q.7 Solve both questions :

Q7.1

What do you understand by fragmentation? Explain the difference between external and internal fragmentations.

Q7.2

What is a thread? Explain the benefits of using threads.

Q.8 Solve both questions :

Q8.1

What do you understand by address binding? Explain the various address binding schemes.

Q8.2

Explain the importance of virtual memory.

Q.9 Solve both questions :

Q9.1

What do you understand by disk scheduling? Describe seek time and rotational latency.

Q9.2

Describe SCAN scheduling. How is C-SCAN different from SCAN?

Q.10 Write short notes on (any three):

Q10.1

Micro kernel

Q10.2

Bankers Algorithm

Q10.3

Process control block

Q10.4

Paging

Q10.5

Indexed allocation

2013 V4 105314

Examination 2013

Time 3 hours

Full Marks 70

Instructions:

The marks are indicated in the right-hand margin.
There are TEN questions in this paper.
Attempt any FIVE questions.

Q.1 Solve all questions :

Q1.1

Define operating system. What are the duties performed by an operating system?

Q1.2

What are the main advantages of time sharing systems?

Q1.3

What are system calls? Explain their importance.

Q.2 Solve both questions :

Q2.1

Differentiate between a file and a Directory. Justify for the need of file system.

Q2.2

Explain the main features of general graph directory structure.

Q.3 Solve both questions :

Q3.1

What do you understand by deadlock? Discuss the methods to avoid deadlock in an operating system.

Q3.2

Explain the working of resource allocation graph.

Q.4 Solve both questions :

Q4.1

What is the difference between physical and logical address space?

Q4.2

What are semaphores? How can they be used to handle the process synchronization problem?

Q.5 Solve both questions :

Q5.1

What are the benefits of segmentation?

Q5.2

Explain the segmentation technique with the help of a diagram.

Q.6 Solve both questions :

Q6.1

Explain the following terms:
(i) Turnaround time
(ii) Waiting time
(iii) Response time
(iv) Throughput

Q6.2

Consider the following page replacement string: 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1
Find the number of page faults using the following algorithms for a memory of three frames:
(i) FIFO algorithm
(ii) LRU algorithm

Q.7 Solve both questions :

Q7.1

What do you understand by fragmentation? Explain the difference between external and internal fragmentations.

Q7.2

What is a thread? Explain the benefits of using threads.

Q.8 Solve both questions :

Q8.1

What do you understand by address binding? Explain the various address binding schemes.

Q8.2

Explain the importance of virtual memory.

Q.9 Solve both questions :

Q9.1

What do you understand by disk scheduling? Describe seek time and rotational latency.

Q9.2

Describe SCAN scheduling. How is C-SCAN different from SCAN?

Q.10 Write short notes on (any three):

Q10.1

Micro kernel

Q10.2

Bankers Algorithm

Q10.3

Process control block

Q10.4

Paging

Q10.5

Indexed allocation