Recent questions and answers in Operating System

28 votes

2 answers

1

GATE CSE 1994 | Question: 1.13
A memory page containing a heavily used variable that was initialized very early and is in constant use is removed then LRU page replacement algorithm is used FIFO page replacement algorithm is used LFU page replacement algorithm is used None of the above

Subbu. answered in Operating System 3 hours ago

by Subbu.

7.7k views

0 votes

1 answer

2

paging question
If the page table is 2MB, frame size is 1KB and each entry in page table has 16 bits then, does each entry of the page table occupy 1KB in main memory?

Vishal_kumar98 answered in Operating System 2 days ago

by Vishal_kumar98

43 views

0 votes

1 answer

3

Applied Roots Topic Test
Which of the following are true ? Deadlock detection in single instance resource type is guaranteed. Deadlock detection in multi instance resource type is guaranteed. My answer : Both A and B because deadlock detection in single instance resource type can be done using ... or will enter deadlock from the current state. Given answer : Only A. Can't get why option B is false.

Vishal_kumar98 answered in Operating System 2 days ago

by Vishal_kumar98

49 views

66 votes

9 answers

4

GATE CSE 2013 | Question: 29
Consider a hard disk with $16$ recording surfaces $(0-15)$ having $16384$ cylinders $(0-16383)$ and each cylinder contains $64$ sectors $(0-63)$. Data storage capacity in each sector is $512$ bytes. Data are organized cylinder-wise and the addressing ... cylinder number of the last sector of the file, if it is stored in a contiguous manner? $1281$ $1282$ $1283$ $1284$

krazyNinja answered in Operating System 3 days ago

17.6k views

0 votes

0 answers

5

It is homework
Consider the following code fragment executed by a process of PID=1055. int main() { int a=5; if (fork() == 0) { a = a + 5; b= getppid(); printf(“%d, %d \n”, a, b); } else { c = a - 5; d= getpid(); printf (“%d, %d \n”, c, d); } return 0; } Write the output of a, b, c, d?

Piyush1232001 asked in Operating System 4 days ago

by Piyush1232001

24 views

0 votes

0 answers

6

applied gate test series
Variable X starts at zero and is a shared variable. Variables A and B are not shared variables. If Processes P1 and P2 execute only once at any speed, the largest possible value of X is ____.

jugnu1337 asked in Operating System Sep 21

33 views

21 votes

4 answers

7

GATE CSE 1992 | Question: 02,x, ISRO2015-35
At a particular time of computation, the value of a counting semaphore is $7$. Then $20$ $P$ operations and $15$ $V$ operations were completed on this semaphore. The resulting value of the semaphore is : $42$ $2$ $7$ $12$

imkeshav answered in Operating System Sep 19

9.7k views

0 votes

0 answers

8

Pearson Crack The Gate Series Unit 7 Chapter 2 Practice Problems I Question 11
Consider two process P, and P, which share the following variables: boolean flag [2]; /*initially false*/ int turn; These two processes, Pi(i = 0 or 1), Pj (j = 1 or 0) execute the following code: do { flag [i] = TRUE; while (flag ... (iii) Bounded Waiting (i) , (ii) only (ii), (iii) only (i), (iii) only (I), (ii), (iii)

AzaX asked in Operating System Sep 18

by AzaX

23 views

1 vote

1 answer

9

Is P.K Biswas sir OS playlist Complete or Has extra videos ?
Has anyone followed prof. P.K Biswas sir lectures on OS from this playlist https://www.youtube.com/playlist?list=PLLDC70psjvq5hIT0kfr1sirNuees0NIbG ? Is it complete or have extra videos which i can ignore as per the syllabus? ( ... resources for them. ) Will it be sufficient to follow these lectures + exercise questions from Galvin + PYQ?

nostradamus answered in Operating System Sep 16

66 views

75 votes

13 answers

10

GATE IT 2007 | Question: 83
The head of a hard disk serves requests following the shortest seek time first (SSTF) policy. What is the maximum cardinality of the request set, so that the head changes its direction after servicing every request if the total number of tracks are $2048$ and the head can start from any track? $9$ $10$ $11$ $12$

KunuSwavik answered in Operating System Sep 15

14.5k views

0 votes

0 answers

11

CacheMemory Problem
A computer system contains a main memory of 32KB. It also has a 4KB cache divided into four-lines/set with 64B per line. Assume that the cache is initially empty. The processor fetches words from locations 0, 1, 2, . . ., 4351 in that order. ... the improvement resulting from the use of the cache. Assume an LRU policy for block replacement. Show the state of cache at the end closed

Anisul Mahmud asked in Operating System Sep 13

by Anisul Mahmud

59 views

4 votes

5 answers

12

GATE CSE 1998 | Question: 25b
Consider a disk with $c$ cylinders, $t$ tracks per cylinder, $s$ sectors per track and a sector length $s_l$. A logical file $d_l$ with fixed record length $r_l$ is stored continuously on this disk starting at location $(c_L, t_L, s_L)$, where ... the formula to calculate the disk address (i.e. cylinder, track and sector) of a logical record n assuming that $r_l=s_l$.

Jyotish Ranjan answered in Operating System Sep 11

by Jyotish Ranjan

1.5k views

0 votes

1 answer

13

Zeal Test Series 2019: Operating System - Context Switch

anwesha-me answered in Operating System Sep 5

279 views

0 votes

1 answer

14

madeeasytestseries
Consider the following segment: int count = 0; void tally( ) { for(int i=1;i<=5;i++) count=count+1; } main() { parbegin tally(); tally(); parend } Note: Assume the count = count + 1; will execute in 3' different instructions. ... can occur while executing the above instructions. After completion of both functions of tally( ), The minimum final values of count is.....?

Muquim answered in Operating System Aug 23

by Muquim

327 views

6 votes

4 answers

15

OS:- Round Robin scheduling
If we have only one process in ready queue with burst time "m", then how many context switching will happen using round robing scheduling with time quantum q ,where q<m.Assume that dispatching the process first time is not counted as a context switch.

Varn Gupta answered in Operating System Aug 21

2.2k views

0 votes

2 answers

16

Round Robin
In case of Round robin algorithm with time quantum = 2s, and process P1 starting at t=0 and have processes P2, P3 in queue If a process P4 arrives at t =2s, but at the same time t=2s, P1 which was executing is preempted since the quantum expires. Which process will be ... mean the waiting queue will have the order P2, P3, P4, P1 or P2, P3, P1, P4 because there is race between P4 and P1.

Varn Gupta answered in Operating System Aug 21

810 views

13 votes

4 answers

17

ISRO2017-51
Wha is the output of the following program? main() { int a = 10; if(fork()) == 0)) a++; printf("%d\n",a); } 10 and 11 10 11 11 and 11

Nagasaikanmatha answered in Operating System Aug 20

by Nagasaikanmatha

5.8k views

57 votes

8 answers

18

GATE IT 2005 | Question: 41
Given below is a program which when executed spawns two concurrent processes : semaphore $X : = 0 ;$ /* Process now forks into concurrent processes $P1$ & $P2$ */ $\begin{array}{|l|l|}\hline \text{$P1$} & \text{$ ... (II) are true. (I) is true but (II) is false. (II) is true but (I) is false Both (I) and (II) are false

Dharmesh Dubey answered in Operating System Aug 18

by Dharmesh Dubey

13.9k views

48 votes

7 answers

19

GATE CSE 1990 | Question: 7-b
In a two-level virtual memory, the memory access time for main memory, $t_{M}=10^{-8}$ sec, and the memory access time for the secondary memory, $t_D=10^{-3}$ sec. What must be the hit ratio, $H$ such that the access efficiency is within $80$ percent of its maximum value?

sarthak_07 answered in Operating System Aug 8

11.2k views

27 votes

4 answers

20

GATE CSE 1995 | Question: 1.15
Which scheduling policy is most suitable for a time shared operating system? Shortest Job First Round Robin First Come First Serve Elevator

Dharmesh Dubey answered in Operating System Aug 4

by Dharmesh Dubey

8.9k views

2 votes

1 answer

21

MadeEasy Subject Test: Operating System - Resource Allocation
i m calculating again n again but getting same ans.. what m i missing here pls varify once...

Lakshya herau answered in Operating System Jul 28

by Lakshya herau

268 views

1 vote

1 answer

22

NIELIT 2017 DEC Scientific Assistant A - Section B: 48
The process of loading the operating system into memory is called : Booting Spooling Thrashing Formatting

Adarsh Rai answered in Operating System Jul 27

393 views

0 votes

2 answers

23

Andrew S. Tanenbaum (OS) Edition 4 Exercise 1 Question 15 (Page No. 82)
Consider a computer system that has cache memory, main memory (RAM) and disk, and an operating system that uses virtual memory. It takes $1$ nsec to access a word from the cache, $10$ nsec to access a word from the RAM, and ... and main memory hit rate (after a cache miss) is $99\%$, what is the average time to access a word?

sridhar15399 answered in Operating System Jul 18

by sridhar15399

280 views

0 votes

2 answers

24

Process Management
The Process which are in Blocked Suspended State or In Ready Suspended State, where that Process lies, in Main Memory or Disk ?

asqwer answered in Operating System Jul 18

by asqwer

228 views

0 votes

1 answer

25

Galvin Edition 9 Exercise 1 Question 22 (Page No. 51)
Many SMP(Symmetric Multiprocessing) systems have different levels of caches; one level is local to each processing core, and another level is shared among all processing cores. Why are caching systems designed this way ?

asqwer answered in Operating System Jul 16

by asqwer

223 views

0 votes

1 answer

26

Galvin Edition 9 Exercise 1 Question 21 (Page No. 51)
Some computer systems do not provide a privileged mode of operation in hardware. Is it possible to construct a secure operating system for these computer systems ? Give arguments both that it is and that it is not possible.

kamii answered in Operating System Jul 15

by kamii

148 views

15 votes

2 answers

27

GATE CSE 1990 | Question: 9b
Assuming the current disk cylinder to be $50$ and the sequence for the cylinders to be $1, 36, 49, 65, 53, 12, 3, 20, 55, 16, 65$ and $78$ find the sequence of servicing using Shortest seek time first (SSTF) and Elevator disk scheduling policies.

adad20 answered in Operating System Jul 9

by adad20

2.7k views

1 vote

1 answer

28

process synchronization
I have some doubts : 1. If progress property is satisfied as per the statement (If process does not want to enter the critical section , it should not block others from entering) but there is a possibility of Deadlock as well , then also ... 6. Does freedom from starvation implies bounded wait? I am getting confused , please clarify above doubts with explanation. Thank you.

asqwer answered in Operating System Jul 9

by asqwer

401 views

23 votes

3 answers

29

TIFR2013-B-14
Assume a demand paged memory system where ONLY THREE pages can reside in the memory at a time. The following sequence gives the order in which the program references the pages. $1, 3, 1, 3, 4, 2, 2, 4$ Assume that least frequently used page is replaced when ... respectively $1,1,1,2$ times, respectively $1,1,1,1$ times, respectively $2,1,2,2$ times, respectively None of the above

Yawar Rmir answered in Operating System Jul 1

1.5k views

2 votes

3 answers

30

GATE CSE 2021 Set 1 | Question: 11
In the context of operating systems, which of the following statements is/are correct with respect to paging? Paging helps solve the issue of external fragmentation Page size has no impact on internal fragmentation Paging incurs memory overheads Multi-level paging is necessary to support pages of different sizes

Arjun answered in Operating System Jun 13

by Arjun

2.4k views

3 votes

2 answers

31

GATE CSE 2021 Set 2 | Question: 14
Which of the following statement(s) is/are correct in the context of $\text{CPU}$ scheduling? Turnaround time includes waiting time The goal is to only maximize $\text{CPU}$ utilization and minimize throughput Round-robin policy ... $\text{CPU}$ time required by each of the processes is not known apriori Implementing preemptive scheduling needs hardware support

Arjun answered in Operating System Jun 13

by Arjun

1.9k views

4 votes

2 answers

32

GATE CSE 2021 Set 2 | Question: 43
Consider a computer system with multiple shared resource types, with one instance per resource type. Each instance can be owned by only one process at a time. Owning and freeing of resources are done by holding a global lock $(L)$. ... not occur The scheme may lead to live-lock The scheme may lead to starvation The scheme violates the mutual exclusion property

Arjun answered in Operating System Jun 13

by Arjun

1.6k views

5 votes

3 answers

33

2 level paging
consider a system using 2 level paging applicable page table is divided into 2K pages each of size 4 KB. if pas is 64 MB which is divided into 16K frames memory is byte addressable . page tabke entry size is 2 bytes in both the levels calculate the length of logical and physical address. total number of entry at second level

prkshprasad1 answered in Operating System Jun 13

by prkshprasad1

4.1k views

0 votes

2 answers

34

Magnetic Disk
Ans. 52 msec

i_am_SiddhanT answered in Operating System Jun 11

by i_am_SiddhanT

465 views

37 votes

6 answers

35

GATE IT 2005 | Question: 19, UGCNET-June2012-III: 57
A user level process in Unix traps the signal sent on a Ctrl-C input, and has a signal handling routine that saves appropriate files before terminating the process. When a Ctrl-C input is given to this process, what is the mode in which the signal handling routine executes? User mode Kernel mode Superuser mode Privileged mode

HitechGa answered in Operating System Jun 11

6.8k views

2 votes

2 answers

36

ACE Model Grand Test 2003 Operating System
The state of a process during context switching is 1. May be busy 2. May be idle 3. Always idle 4. always busy

endurance1 answered in Operating System Jun 8

539 views

0 votes

1 answer

37

GeeksforGeeks
Suppose that the running time for each process in milliseconds is an exponential random variable with parameter λ=1/20. If process P1 arrives immediately ahead of the process P2 in the running state, then the probability that process P2 will have to wait more than 20 milliseconds is ... . A 0.274 B 0.324 C 0.428 D 0.368 How to approach this. even not able to understand the question.

Pavankumar07 answered in Operating System Jun 2

by Pavankumar07

224 views

0 votes

1 answer

38

Read system call
The read system call to fetch data from a file always blocks the invoking process.[True / False] [blocking means context switching to another process]

afroze answered in Operating System May 24

by afroze

96 views

1 vote

1 answer

39

NIELIT 2017 July Scientist B (IT) - Section B: 44
Consider three processes (process id $0,1,2$ respectively) with compute time bursts $2,4$ and $8$ time units. All processes arrive at time zero. Consider the Longest Remaining Time First (LRTF) scheduling algorithm. In LRTF ties are broken by ... with the lowest process id. The average turn around time is $13$ units $14$ units $15$ units $16$ units

gateankit answered in Operating System May 24

769 views

6 votes

3 answers

40

GATE CSE 2021 Set 1 | Question: 46
Consider the following pseudocode, where $\textsf{S}$ is a semaphore initialized to $5$ in line $\#2$ and $\textsf{counter}$ is a shared variable initialized to $0$ in line $\#1$. Assume that the increment operation in line $\#7$ ... is $0$ after all the threads successfully complete the execution of $\textsf{parop}$ There is a deadlock involving all the threads

sanbaner answered in Operating System May 23

2.7k views

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