Recent questions tagged semaphore / GATE Overflow for GATE CSE

1 votes

1 answer

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

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...

Rahul_Rathod_

1.6k views

Rahul_Rathod_ asked Dec 12, 2018

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. $7$ $8$ $13$ $12$

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 v...

Arjun

967 views

Arjun asked Dec 7, 2018

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

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 o...

Pavan Shetty

906 views

Pavan Shetty asked Nov 22, 2018

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)

I think that statement iii is false , deadlock can arise in both semaphore as well as monitor (mutex)

Magma

721 views

Magma asked Nov 19, 2018

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);

The first known correct software solution to the critical-section problemfor two processes was developed by Dekker. The two processes, P0 andP1, share the following varia...

Chetan Warke

3.1k views

Chetan Warke asked Nov 17, 2018

0 votes

1 answer

66

Testbook test series- how can P2 block P1?

Markzuck

318 views

Markzuck asked Nov 16, 2018

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?

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...

Shaijal Tripathi

1.0k views

Shaijal Tripathi asked Nov 7, 2018

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??

Let X is an Binary Semaphore with waiting Queue in FIFO order.P1P2repeat forever V(X); Compute ; P(X); repea...

jatin khachane 1

691 views

jatin khachane 1 asked Oct 29, 2018

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?

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

233 views

asharani97 asked Oct 27, 2018

0 votes

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

after execution of 15p and 18 v operations semaphore value is same as execution of A. 3P C.12P&15VB.3V ...

Divyanshum29

476 views

Divyanshum29 asked Oct 20, 2018

1 votes

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);

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

1.1k views

srestha asked Oct 4, 2018

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 ?

Semaphore Implementationtypedef struct {int value;struct process *list;} semaphore;Each semaphore has an integer value and a list of processes list. Whena process must wa...

Prince Sindhiya

487 views

Prince Sindhiya asked Aug 6, 2018

1 votes

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)?

Say there are some processes $P_{i},i=1,2....$ work likeP(mutex) {Critical section} V(mutex)And one process $P_{i},i=5$ work likeV(mutex) {Critical section} V(mutex)My qu...

srestha

1.1k views

srestha asked Jul 31, 2018

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)

Given two semaphore n and sNow given 2 situationSituation 1) The producer will be able to add an item to the buffer, but consumer can never consume itSituation 2) Consume...

srestha

669 views

srestha asked Jul 26, 2018

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!

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 ...

iarnav

518 views

iarnav asked Jul 22, 2018

0 votes

1 answer

76

Semaphores Usage

Na462

565 views

Na462 asked Jul 19, 2018

0 votes

1 answer

77

Semaphores

Na462

707 views

Na462 asked Jul 14, 2018

0 votes

0 answers

78

Semaphores

Na462

362 views

Na462 asked Jul 12, 2018

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?

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]); ......

srestha

5.5k views

srestha asked Jul 9, 2018

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....

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 plea...

Na462

182 views

Na462 asked Jul 9, 2018

1 votes

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.

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...

Anwesha Kashyap

2.0k views

Anwesha Kashyap asked Jun 19, 2018

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

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 ho...

shivanisrivarshini

1.6k views

shivanisrivarshini asked May 13, 2018

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?

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

1.2k views

Akash Kumar Roy asked Mar 24, 2018

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

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 usua...

Madhi Varman

529 views

Madhi Varman asked Feb 2, 2018

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$.$

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...

saxena0612

339 views

saxena0612 asked Jan 16, 2018

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.

wait(S);Critical sectionwait(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 situ...

MiNiPanda

1.1k views

MiNiPanda asked Jan 13, 2018

0 votes

2 answers

87

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

Suppose 2 process P1 and P2 are as follows:

Mk Utkarsh

504 views

Mk Utkarsh asked Dec 30, 2017

1 votes

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?

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

Mk Utkarsh

341 views

Mk Utkarsh asked Dec 30, 2017

0 votes

1 answer

89

Subject Topic- Operating systems- Semaphore

VIDYADHAR SHELKE 1

717 views

VIDYADHAR SHELKE 1 asked Dec 25, 2017

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

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 in...

rahul sharma 5

2.6k views

rahul sharma 5 asked Dec 18, 2017

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