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Recent questions tagged semaphore

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61

semaphore
a) s1-wait(p) , s2-wait(q) , s3-wait(q) , s4-wait(p) b) s1-wait(p) , s2-wait(q) , s3-wait(p) , s4-wait(q) c) s1-wait(q) , s2-wait(p) , s3-wait(p) , s4-wait(q) d) none of above

Rahul_Rathod_ asked in Operating System Dec 12, 2018

by Rahul_Rathod_

1.5k views

0 votes

1 answer

62

NIELIT 2018-57
In a system, counting semaphore was initialized to $10$, then $6P$(wait) operations and $4V$ (signal) operations were completed on this semaphore. So _____ is the final value of the semaphore. $7$ $8$ $13$ $12$

Arjun asked in Operating System Dec 7, 2018

by Arjun

955 views

2 votes

1 answer

63

Simple Doubt in counting semaphore
Consider a non-negative counting semaphore S. During an execution, 16P (wait) operations, and 4V (signal) operations are issued in some order. The largest initial value of S for which at least three up operations will remain blocked is ___________ Can someone explain me the solution

Pavan Shetty asked in Operating System Nov 22, 2018

by Pavan Shetty

892 views

0 votes

0 answers

64

Ace Test Series: Operating System - Process Synchronization And Semaphore
I think that statement iii is false , deadlock can arise in both semaphore as well as monitor (mutex)

Magma asked in Operating System Nov 19, 2018

by Magma

717 views

0 votes

1 answer

65

Abraham Silberasch Galvin operating system Book chapter 5 process synchronization
The first known correct software solution to the critical-section problem for two processes was developed by Dekker. The two processes, P0 and P1, share the following variables: boolean flag[2]; /* initially false */ int turn; ... critical section */ turn = j; flag[i] = false; /* remainder section */ } while (true);

Chetan Warke asked in Operating System Nov 17, 2018

by Chetan Warke

3.1k views

0 votes

1 answer

66

Testbook test series- how can P2 block P1?

Markzuck asked in Operating System Nov 16, 2018

319 views

0 votes

1 answer

67

Doubt Counting Semaphore
Assume Counting Semaphore N=8. On performing 10 down() operations by 10 different processes , first 8 will be successful and last two processes will be suspended. Does this mean that the first 8 processes can enter in the CS at the same time? In other words, does counting semaphore can let multiple processes access the CS at the same time?

Shaijal Tripathi asked in Operating System Nov 7, 2018

by Shaijal Tripathi

1.0k views

0 votes

0 answers

68

Self Doubt
Let X is an Binary Semaphore with waiting Queue in FIFO order. P1 P2 repeat forever V(X); Compute ; P(X); repeat forever P(X); Compute ; V(X); P1 P2 repeat forever V(X); Compute ; V(X); repeat forever P(X); Compute ; V(X); In which case Starvation for P2 is possible??

jatin khachane 1 asked in Operating System Oct 29, 2018

by jatin khachane 1

696 views

0 votes

1 answer

69

Self Doubt
How to decide in which question process will run completely and where preemption needs to be taken while solving semaphore questions? Is there any predefined method?

asharani97 asked in Operating System Oct 27, 2018

229 views

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1 answer

70

test series
after execution of 15p and 18 v operations semaphore value is same as execution of A. 3P C.12P&15V B.3V C. Both B&C what is the solution

Divyanshum29 asked in Operating System Oct 20, 2018

by Divyanshum29

478 views

1 vote

0 answers

71

Semaphore
Will it causing deadlock? How do we fixed it? P1: P2: Wait(S); Wait(Q); Wait(Q); Wait(S); ........ ............. Signal(S); Signal(Q); Signal(Q); Signal(S);

srestha asked in Operating System Oct 4, 2018

1.1k views

0 votes

0 answers

72

self doubt _counting semaphore
Semaphore Implementation typedef struct { int value; struct process *list; } semaphore; Each semaphore has an integer value and a list of processes list. When a process must wait on a semaphore, it is added to the list of processes. A signal() ... again $P_4$ comes out of critical section then again such thing will happen, please tell me where i am making mistake ?

Prince Sindhiya asked in Operating System Aug 6, 2018

by Prince Sindhiya

475 views

1 vote

1 answer

73

Semaphore
Say there are some processes $P_{i},i=1,2....$ work like P(mutex) {Critical section} V(mutex) And one process $P_{i},i=5$ work like V(mutex) {Critical section} V(mutex) My question is for same C.S., how two process work differently?(One start with coded up and other one start with coded down)?

srestha asked in Operating System Jul 31, 2018

1.1k views

0 votes

1 answer

74

Semaphore
Given two semaphore n and s Now given 2 situation Situation 1) The producer will be able to add an item to the buffer, but consumer can never consume it Situation 2) Consumer succeeds in acquiring semaphore s, when buffer is empty What will be initial value of n and s to fulfill these two condition separately? (U can describe the situation with few words)

srestha asked in Operating System Jul 26, 2018

674 views

0 votes

0 answers

75

#OS #Semaphores Producer Consumer Problem Self Doubt.
I know, that both P and C can go and fall into sleeping state in case of preemption and this can be solved via Semaphores. Now, my doubt is that integer bit that will be set by the P and being sent to C and C will see the semaphore bit ... ? Basically, both P and C can send this integer bit or only P can send this to C to wake him up? Thank you!

iarnav asked in Operating System Jul 22, 2018

by iarnav

522 views

0 votes

1 answer

76

Semaphores Usage

Na462 asked in Operating System Jul 19, 2018

by Na462

560 views

0 votes

1 answer

77

Na462 asked in Operating System Jul 14, 2018

by Na462

701 views

0 votes

0 answers

78

Na462 asked in Operating System Jul 12, 2018

by Na462

355 views

2 votes

1 answer

79

Semaphore
Let m[0]....m[4] be mutexes (binary semaphores) and P[0].......P[4] be processes. Suppose each process P[i] executes the following: wait (m[i]; wait (m(i+1) mode 3]); ........... release (m[i]); release (m(i+1) mod 3]); Will it cause Starvation and deadlock? If the ... (m(i+1) mode 5]); ........... release (m[i]); release (m(i+1) mod 5]); Is there any change in answer in this question?

srestha asked in Operating System Jul 9, 2018

5.5k views

0 votes

0 answers

80

Semaphores Uasge
Here A is the Option i get it. But i cant understand how Counting Semaphores can be implemented using Binary Semaphores and Machine instructions. Some light over here please....

Na462 asked in Operating System Jul 9, 2018

by Na462

172 views

1 vote

2 answers

81

Interview: ISI mtech CS
Provide a synchronizing mechanism using semaphores such that a tiger and an elephant are not allowed to drink water from a pond simultaneously whereas more than one tiger or more than one elephant can.

Anwesha Kashyap asked in Operating System Jun 19, 2018

by Anwesha Kashyap

2.0k views

0 votes

2 answers

82

final value of semaphore
There are Three processesP1,P2,P3 sharing a semaphore for synchronizing a variable, Initial value of semaphore is one. Assume that negative value of semaphore tells us how many processes are waiting in queue. Processes access the semphore in following order a. P2 needs to access ... e. P1 exits critical section The final value of semaphore will be 1. 0 2. 1 3. -1 4. -2

shivanisrivarshini asked in Operating System May 13, 2018

by shivanisrivarshini

1.5k views

0 votes

3 answers

83

My personal doubt
if s is a binary semaphore and the initial value of s is 1 then can 'signal' be performed on s ? what will happen if signal(s) is performed?

Akash Kumar Roy asked in Operating System Mar 24, 2018

by Akash Kumar Roy

1.2k views

2 votes

0 answers

84

Semaphores
If two processes R1 and R2 accessing the shared variables A and B protected by two binary semaphores SA and SB respectively, both initialized to 1. R and Q denote the usual semaphore operators, where R decrements the semaphore value, and Q increments the semaphore value. The pseudo code of R1 and R2 is as ... ) R(SA ),R(SB ),R(SA ),R(SB ) R(SA ),R(SB ),R(SB ),R(SA ) None of the above

Madhi Varman asked in Operating System Feb 2, 2018

by Madhi Varman

532 views

2 votes

1 answer

85

Semaphores_Implemenation
Consider this implementation of semaphores b/w these $2$ processes : PROCESS-1 : V(s) CS P(S) PROCESS-2: P(s) CS V(S) Assume that semaphore "s" is intialized to $0$ at initial stage . Comment on these statments : Process -$1$ can starve$.$ Process=$2$ can starve$.$

saxena0612 asked in Operating System Jan 16, 2018

340 views

3 votes

0 answers

86

Semaphore doubt
wait(S); Critical section wait(S); S is a binary semaphore initialised to 1. Suppose there are n processes competing for the CS. Only one can enter into it. Is this the situation of deadlock or starvation? I think it's deadlock because other ... one process is getting executed so it's not deadlock as in case of deadlock none of the processes can proceed. Please clarify.

MiNiPanda asked in Operating System Jan 13, 2018

1.0k views

0 votes

2 answers

87

Gateforum Test series
Suppose 2 process P1 and P2 are as follows:

Mk Utkarsh asked in Operating System Dec 30, 2017

508 views

1 vote

0 answers

88

Personal doubt
(i) What is Load/Store? (ii) Explain fetch-and-set. is there any relation between these two or any basis of comparision?

Mk Utkarsh asked in Operating System Dec 30, 2017

340 views

0 votes

1 answer

89

Subject Topic- Operating systems- Semaphore

VIDYADHAR SHELKE 1 asked in Operating System Dec 25, 2017

by VIDYADHAR SHELKE 1

742 views

3 votes

3 answers

90

MadeEasy Test Series: Operating System - Semaphore
Consider program for P1 and P2: Here, m and n are binary semaphore variables whose values are initially initialized to 1. x and y are shared resources whose values are initialized to 0. Which of the following holds by above processes ... B :-Deadlock and race condition C :-No deadlocks and no race condition D:- Race condition and no deadlock

rahul sharma 5 asked in Operating System Dec 18, 2017

by rahul sharma 5

2.6k views

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Recent questions tagged semaphore