Search results for semaphore / GATE Overflow for GATE CSE

18 votes

2 answers

1

GATE CSE 2023 | Question: 28
Consider the two functions $\textsf{incr}$ and $\textsf{decr}$ shown below. incr(){ decr(){ wait(s); wait(s); X = X+1; X = X-1; signal(s); signal(s); } } There are $5$ threads each invoking $\textsf{incr}$ once, and $3$ threads each ... of the following choices corresponds to the minimum possible values of $\text{V1, V2},$ respectively? $15,7$ $7,7$ $12,7$ $12,8$

Consider the two functions $\textsf{incr}$ and $\textsf{decr}$ shown below. incr(){ decr(){ wait(s); wait(s); X = X+1; X = X-1; signal(s); signal(s); } }There are $5$ thr...

admin

12.4k views

admin asked Feb 15, 2023

26 votes

5 answers

2

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 : $42$ $2$ $7$ $12$

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 resu...

Kathleen

24.0k views

Kathleen asked Sep 12, 2014

68 votes

8 answers

3

GATE CSE 2008 | Question: 63
The $P$ and $V$ operations on counting semaphores, where s is a counting semaphore, are defined as follows: $P(s):$ $s=s-1;$ If $s < 0$ then wait; $V(s):$ $s=s+1;$ If $s \leq0$ then wake up process waiting on s; Assume that $P_b$ and $V_b$ the wait ... $x_b$ and $y_b$ are respectively $0$ and $0$ $0$ and $1$ $1$ and $0$ $1$ and $1$

The $P$ and $V$ operations on counting semaphores, where s is a counting semaphore, are defined as follows:$P(s):$$s=s-1;$If $s < 0$ then wait;$V(s):$$s=s+1;$If $s \leq0$...

Kathleen

23.2k views

Kathleen asked Sep 12, 2014

21 votes

4 answers

4

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

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 li...

Arjun

13.5k views

Arjun asked Feb 18, 2021

51 votes

10 answers

5

GATE CSE 2016 Set 2 | Question: 49
Consider a non-negative counting semaphore $S$. The operation $P(S)$ decrements $S$, and $V(S)$ increments $S$. During an execution, $20$ $P(S)$ operations and $12$ $V(S)$ operations are issued in some order. The largest initial value of $S$ for which at least one $P(S)$ operation will remain blocked is _______

Consider a non-negative counting semaphore $S$. The operation $P(S)$ decrements $S$, and $V(S)$ increments $S$. During an execution, $20$ $P(S)$ operations and $12$ $V(S)...

Akash Kanase

15.9k views

Akash Kanase asked Feb 12, 2016

5 votes

1 answer

6

GO Classes Test Series 2024 | Mock GATE | Test 13 | Question: 49
We want to use semaphores to implement a shared critical section (CS) among three threads $\mathrm{T} 1$, $\mathrm{T} 2$, and $\mathrm{T} 3$ ... What is the minimum number of binary semaphores we need in order to enforce this ordering?

We want to use semaphores to implement a shared critical section (CS) among three threads $\mathrm{T} 1$, $\mathrm{T} 2$, and $\mathrm{T} 3$.We want to enforce the execut...

GO Classes

482 views

GO Classes asked Jan 28

12 votes

3 answers

7

GATE CSE 2022 | Question: 9
Consider the following threads, $\text{T}_{1}, \text{T}_{2},$ and $\text{T}_{3}$ executing on a single processor, synchronized using three binary semaphore variables, $\text{S}_{1}, \text{S}_{2},$ and $\text{S}_{3},$ operated upon using standard $\textsf{wait}()$ ... $\text{S}_{1} = 0; \text{S}_{2} = 1; \text{S}_{3} = 1$

Consider the following threads, $\text{T}_{1}, \text{T}_{2},$ and $\text{T}_{3}$ executing on a single processor, synchronized using three binary semaphore variables, $\t...

Arjun

9.1k views

Arjun asked Feb 15, 2022

4 votes

2 answers

8

GO Classes Test Series 2024 | Mock GATE | Test 11 | Question: 19
Consider three concurrently executing threads in the same process using two semaphores $\text{s}1$ and $\text{s2}.$ Assume $\text{s1}$ has been initialized to $1$, while $\text{s2}$ has been initialized to $0.$ ... ); /* thread C */ P(s1); x = x+3; V(s2); V(s1); $6$ $12$ $18$ $36$

Consider three concurrently executing threads in the same process using two semaphores $\text{s}1$ and $\text{s2}.$ Assume $\text{s1}$ has been initialized to $1$, while ...

GO Classes

587 views

GO Classes asked Jan 13

0 votes

1 answer

9

Semaphores
Can a counting semaphore acquire a negative value? S = 2; 15 P operations done, should the semaphore be 0 or -13

Can a counting semaphore acquire a negative value?S = 2;15 P operations done, should the semaphore be 0 or -13

Mrityudoot

246 views

Mrityudoot asked Jan 27

0 votes

0 answers

10

Operating system binary semaphores
Find initial values of binary semaphores X and Y. P and V operation for counting semaphore b is defined as: P(b): b--; wait if b<0; V(b): b++; wakeup any waiting process in b if b<=0; Pa (wait) and Va (signal) are implemented as: P(b): Pa(Y); b--; if(b<0) { Va(Y); Pa(X); } else Va(Y); V(b): Pa(Y); b++; if(b<=0) { Va(Y); Va(X); }

Find initial values of binary semaphores X and Y. P and V operation for counting semaphore b is defined as:P(b): b ; wait if b<0;V(b): b++; wakeup any waiting process in ...

jasper

383 views

jasper asked Oct 21, 2023

19 votes

3 answers

11

GATE CSE 2020 | Question: 34
Each of a set of $n$ processes executes the following code using two semaphores $a$ and $b$ initialized to $1$ and $0$, respectively. Assume that $\text{count}$ is a shared variable initialized to $0$ ... all processes execute CODE SECTION P mutually exclusively. It ensures that at most $n-1$ processes are in CODE SECTION P at any time.

Each of a set of $n$ processes executes the following code using two semaphores $a$ and $b$ initialized to $1$ and $0$, respectively. Assume that $\text{count}$ is a shar...

Arjun

13.8k views

Arjun asked Feb 12, 2020

0 votes

1 answer

12

process synchronization
How to approach synchronization (specifically semaphore) question, there size are really intimidating and i’m unable to decode the code written? What to do??

How to approach synchronization (specifically semaphore) question, there size are really intimidating and i’m unable to decode the code written? What to do??

N3314nch41

362 views

N3314nch41 asked Sep 10, 2023

0 votes

1 answer

13

NPTEL : Synchronisation (semaphore)
In a certain application, the initial value of a counting semaphore s is 10. The following operations were completed on the semaphore in the given order 5P, 20P, 2V, 18P, 5V, 10P, 1V. The new value of counting semaphore is _____________ ?

In a certain application, the initial value of a counting semaphore s is 10. The following operations were completed on the semaphore in the given order 5P, 20P, 2V, 18P,...

roopkathaaa

1.3k views

roopkathaaa asked Aug 25, 2023

0 votes

1 answer

14

OS handout
Let m[0]…m[4] be mutexes (binary semaphores) and P[0] …. P[4] be processes. Suppose each process P[i] executes the following: P(i) { while(1) { P(m[i]); P(m[(i+1)%4]; <CS> V(m[i]); V(m[(i+1)%4]; } } What is the maximum no. Of processes that can be in<CS> .......

Let m[0]…m[4] be mutexes (binary semaphores) and P[0] …. P[4] be processes.Suppose each process P[i] executes the following:P(i){ while(1) { P(m[i]); ...

Aniket1710

446 views

Aniket1710 asked Jul 20, 2023

14 votes

11 answers

15

ISRO2015-30
Semaphores are used to solve the problem of Race Condition Process Synchronization Mutual Exclusion None of the above I and II II and III All of the above None of the above

Semaphores are used to solve the problem ofRace ConditionProcess SynchronizationMutual ExclusionNone of the aboveI and IIII and IIIAll of the aboveNone of the above

ajit

21.6k views

ajit asked Oct 12, 2015

0 votes

1 answer

16

GATE CSE 2023 | Memory Based Question: 19
incr() { wait(s) x = x+1 signal(s) } decr() { wait(s) x = x-1 signal(s) } Shared integer variable $\mathrm{x}$ initialized with $10.$ There are five threads which are calling incr() and there are three threads which are calling decr() ... $s=2$ minimum possible value of $\mathrm{x}$ is $\mathrm{V}_2$ $15,8$ $12,8$ $15,7$ $12,7$

incr(){ wait(s) x = x+1 signal(s) } decr() { wait(s) x = x–1 signal(s) }Shared integer variable $\mathrm{x}$ initialized w...

GO Classes

1.6k views

GO Classes asked Feb 5, 2023

0 votes

0 answers

17

OS Self doubt (Semaphore)
At the end of chapter 2, we studied a solution to the readers and writers problem, given below:- In this solution, as long as one reader is having the resource any new reader can get access to the resource. Thus, the writer will ... expressing interest the writer will also have to wait for all the existing resource-occupyingreader(s) to be done and release the resource.

At the end of chapter 2, we studied a solution to the readers and writers problem, given below:-In this solution, as long as one reader is having the resource any new rea...

legacy

316 views

legacy asked Nov 27, 2022

0 votes

1 answer

18

Process Synchronisation
What is the significance of infinite loop that is written in every example of process synchronisation? What would happen if there wasn't any infinite loop?

What is the significance of infinite loop that is written in every example of process synchronisation? What would happen if there wasn't any infinite loop?

ajayraho

911 views

ajayraho asked Oct 23, 2022

2 votes

1 answer

19

Binary Semaphore
Say there is a Binary semaphore R, initialized to 0. Say process X and Y are working on R. At T1 :- X has performed P(R); X gets blocked and gets added in Process Queue. At T2 :-Y has performed V(R); Will Process X get unblocked and removed from ready queue? Which process will run after Y has performed V(R)? Process Y or Process X?

Say there is a Binary semaphore R, initialized to 0. Say process X and Y are working on R.At T1 :- X has performed P(R); X gets blocked and gets added in Process Queue.At...

subhashchaganti

520 views

subhashchaganti asked Sep 21, 2022

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