Recent questions tagged process-synchronization / GATE Overflow for GATE CSE

6 votes

4 answers

361

semaphores
Consider a schedule with 3 processes A,B and C, binary semaphores are S =1 , T=0 , Z=0 initially ; Process A { while(1) { P(S) printf("*"); V(T) } } Process B { P(T) V(Z) } Process C { P(Z) V(S) } What is the maximum number of times * is printed?

Consider a schedule with 3 processes A,B and C, binary semaphores are S =1 , T=0 , Z=0 initially ;Process A { while(1) { P(S) printf("*"); V(T) } } Process B { P(T) V(Z) ...

Akriti sood

1.8k views

Akriti sood asked Sep 26, 2016

4 votes

1 answer

362

MadeEasy Test Series: Operating System - Process Synchronization

thor

958 views

thor asked Sep 25, 2016

1 votes

1 answer

363

Mutual exclusion :
Can Mutual exclusion can be enforced with a general semaphore initial value is greater than 1 ? I think yes. Consider a semaphore $S = 2$, and following code segment for both processes. P(S); P(S); <Critical Section> V(S); V(S);

Can Mutual exclusion can be enforced with a general semaphore initial value is greater than 1 ?I think yes. Consider a semaphore $S = 2$, and following code segment for b...

thor

1.2k views

thor asked Sep 25, 2016

6 votes

1 answer

364

Synchronization | Self-Doubt
1. Does starvation freedom imply bounded- waiting ? 2. Does bounded- waiting imply starvation freedom ? Explain with example.

1. Does starvation freedom imply bounded- waiting ?2. Does bounded- waiting imply starvation freedom ?Explain with example.

vijaycs

2.1k views

vijaycs asked Sep 19, 2016

0 votes

2 answers

365

GATE Overflow | Operating Systems | Test 1 | Question: 19
The E_CS() and L_CS() functions to implement critical section of a process are realized using Test-and-Set instruction as stated below: void E_CS(X) { while(Test-and-Set(X); } void L_CS(X) { X=0; } In above code snippet, X is a ... into CS in FIFO order more than 1 process can enter into CS at same time i only i and ii ii and iii iv only

The E_CS() and L_CS() functions to implement critical section of a process are realized using Test-and-Set instruction as stated below:void E_CS(X) { while(Test-and-Set(X...

Bikram

493 views

Bikram asked Sep 3, 2016

1 votes

2 answers

366

GATE Overflow | Operating Systems | Test 1 | Question: 15
At a particular time of computation, the value of a counting semaphore is $7$ , then $20$ $P$ operations and 'x' $V$ operations were completed on this semaphore. If the final value of the semaphore is $5$, the value of $x$ should be ____

At a particular time of computation, the value of a counting semaphore is $7$ , then $20$ $P$ operations and 'x' $V$ operations were completed on this semaphore. If the f...

Bikram

295 views

Bikram asked Sep 3, 2016

6 votes

5 answers

367

GATE Overflow | Operating Systems | Test 1 | Question: 9
Each process $P_i$, where $i= 1$ to $9$ is coded as follows repeat P (mutex) {critical section } V (mutex) forever The code for $P_{10}$ is identical except that it uses $V$ (mutex) instead of $P$ (mutex) and vice ... number of processes that can be inside the critical section at any moment if initial value of the semaphore is 1? 1 2 3 none

Each process $P_i$, where $i= 1$ to $9$ is coded as follows repeat P (mutex) {critical section } V (mutex) foreverThe code for $P_{10}$ is identical except that it uses ...

Bikram

897 views

Bikram asked Sep 3, 2016

1 votes

1 answer

368

GATE Overflow | Operating Systems | Test 1 | Question: 5
Two concurrent processes P1 and P2 want to use 2 resources J1 and J2 in a Mutually Exclusive way. Assume that initially J1 and J2 are both free. The programs executed by these two processes are as below : ... deadlock would not occur Mutual Exclusion is guaranteed, deadlock might occur Mutual Exclusion is not guaranteed, deadlock might occur

Two concurrent processes P1 and P2 want to use 2 resources J1 and J2 in a Mutually Exclusive way. Assume that initially J1 and J2 are both free. The programs executed by ...

Bikram

560 views

Bikram asked Sep 3, 2016

4 votes

0 answers

369

GATE Overflow | Operating Systems | Test 1 | Question: 2
Consider Peterson's algorithm for Mutual Exclusion between two concurrent processes $w$ and $f$. The program executed by the processeses are shown below: Process w Process f repeat flag[w]=true; turn=f; while(P) do no-operation; Enter critical ... and turn = w flag[f]=true and turn=f flag[w]=true and turn=f flag[w]=true and turn=w

Consider Peterson's algorithm for Mutual Exclusion between two concurrent processes $w$ and $f$. The program executed by the processeses are shown below:Process wProcess ...

Bikram

491 views

Bikram asked Sep 3, 2016

1 votes

1 answer

370

Is bounded waiting and progress ensured in this code using exchange instruction?
Consider the atomic exchange instruction defined as follows: void exchange (int *a, int *b) { int temp; temp = *b; *b = *a; *a = temp; } Now consider the solution to critical section problem based on ... ..., P(n)); 20 } Does the above code meets bounded waiting and progress requirements of critical section problem?

Consider the atomic exchange instruction defined as follows:void exchange (int *a, int *b) { int temp; temp = *b; *b = *a; *a = temp; }Now consider the soluti...

GateAspirant999

583 views

GateAspirant999 asked Jul 21, 2016

8 votes

3 answers

371

ISRO2016-45
At a particular time of computation the value of a counting semaphore is 7. Then 20 $P$ operations and $x$ $V$ operations were completed on this semaphore. If the new value of semaphore is $5$, $x$ will be 18 22 15 13

At a particular time of computation the value of a counting semaphore is 7. Then 20 $P$ operations and $x$ $V$ operations were completed on this semaphore. If the new val...

Arjun

10.8k views

Arjun asked Jul 6, 2016

6 votes

1 answer

372

ISRO2011-77
In a system using single processor, a new process arrives at the rate of six processes per minute and each such process requires seven seconds of service time. What is the CPU utilization? 70% 30% 60% 64%

In a system using single processor, a new process arrives at the rate of six processes per minute and each such process requires seven seconds of service time. What is th...

go_editor

5.6k views

go_editor asked Jun 24, 2016

12 votes

6 answers

373

ISRO2011-10
Below is the precedence graph for a set of tasks to be executed on a parallel processing system $S$. What is the efficiency of this precedence graph on $S$ if each of the tasks $T_1, \dots, T_8$ takes the same time and the system $S$ has five processors? $25\%$ $40\%$ $50\%$ $90\%$

Below is the precedence graph for a set of tasks to be executed on a parallel processing system $S$.What is the efficiency of this precedence graph on $S$ if each of the ...

go_editor

6.9k views

go_editor asked Jun 21, 2016

12 votes

1 answer

374

ISRO2007-42, UGCNET-June2010-II: 37
Semaphores synchronize critical resources to prevent deadlock synchronize critical resources to prevent contention are used to do I/O are used for memory management

Semaphoressynchronize critical resources to prevent deadlocksynchronize critical resources to prevent contentionare used to do I/Oare used for memory management

go_editor

6.7k views

go_editor asked Jun 10, 2016

15 votes

2 answers

375

ISI2011-PCB-CS-5c
One of your classmates has suggested the following modified version of a standard scheme for solving the $2$-process critical section problem (CSP). shared char want[2] = {0,0}; shared int turn = 0; 1. P_i() 2. { while (1) { 3. turn = j; ... instructions executed by two processes $P_0$ and $P_1$. Modify the above scheme so that it becomes a correct solution to the $2$-process CSP.

One of your classmates has suggested the following modified version of a standard scheme for solving the $2$-process critical section problem (CSP).shared char want = {0...

go_editor

1.2k views

go_editor asked Jun 3, 2016

1 votes

1 answer

376

ISI2012-PCB-CS-1b
Two processes $P_1$ and $P_2$ have a common shared variable count. While $P_1$ increments it, $P_2$ decrements it. Given that $R_0$ is a register, the corresponding assembly language codes are: $P_1$ count++ $P_2$ count-- MOV $count$ $R_0$ ... $P_1$ and $P_2$ are executed simultaneously.

Two processes $P_1$ and $P_2$ have a common shared variable count. While $P_1$ increments it, $P_2$ decrements it. Given that $R_0$ is a register, the corresponding assem...

go_editor

588 views

go_editor asked Jun 2, 2016

10 votes

3 answers

377

ISI2013-PCB-CS-5a
Suppose that an operating system provides two functions, $block()$ which puts the calling process on the blocked queue, and $wakeup(P)$ which moves process $P$ to the runnable queue if it is currently on the blocked queue (otherwise, its behaviour is unpredictable). Consider ... the initialisation of the semaphore(s), and the calls to $wait()$ and $signal()$ made by $A$ and $B$.

Suppose that an operating system provides two functions, $block()$ which puts the calling process on the blocked queue, and $wakeup(P)$ which moves process $P$ to the run...

go_editor

1.1k views

go_editor asked Jun 1, 2016

3 votes

2 answers

378

True False on TSL(Test Set Lock)
Which of the following is true/false Explain it. 1) TSL solution method is deadlock free. 2)TSL solution method is starvation free. 3)TSL solution method process enter into fcfs order.

Which of the following is true/false Explain it.1) TSL solution method is deadlock free.2)TSL solution method is starvation free.3)TSL solution method process enter into...

Nils

2.5k views

Nils asked May 25, 2016

16 votes

2 answers

379

CMI2012-A-10
Consider the following functions $f$ and $g$. f(){ x = x-50; y = y+50; } g( ) { a = a+x; a = a+y; } Suppose we start with initial values of $100$ for $x, 200$ for $y$, and $0$ for $a$, and then execute $f$ and $g$ in parallel - that ... either execute one statement from $f$ or one statement from $g$. Which of the following is not a possible final value of $a$? $300$ $250$ $350$ $200$

Consider the following functions $f$ and $g$. f(){ x = x-50; y = y+50; }g( ) { a = a+x; a = a+y; }Suppose we start with initial values of $100$ for $x, 200$ for $y$, and ...

go_editor

1.3k views

go_editor asked May 22, 2016

55 votes

7 answers

380

GATE CSE 2003 | Question: 81
Suppose we want to synchronize two concurrent processes $P$ and $Q$ using binary semaphores $S$ and $T$. The code for the processes $P$ and $Q$ ... $1$ $V(S)$ at $W, V(T)$ at $X, P(S)$ at $Y, P(T)$ at $Z, S$ and $T$ initially $1$

Suppose we want to synchronize two concurrent processes $P$ and $Q$ using binary semaphores $S$ and $T$. The code for the processes $P$ and $Q$ is shown below.$$\begin{ar...

go_editor

15.0k views

go_editor asked Apr 24, 2016

42 votes

4 answers

381

GATE CSE 2006 | Question: 79
Barrier is a synchronization construct where a set of processes synchronizes globally i.e., each process in the set arrives at the barrier and waits for all others to arrive and then all processes leave the barrier. Let the number of processes ... at the beginning of the barrier and re-enabled at the end. The variable process_left is made private instead of shared

Barrier is a synchronization construct where a set of processes synchronizes globally i.e., each process in the set arrives at the barrier and waits for all others to arr...

go_editor

8.4k views

go_editor asked Apr 24, 2016

8 votes

2 answers

382

GATE CSE 1991 | Question: 11,b
Consider the following scheme for implementing a critical section in a situation with three processes $P_i, P_j$ and $P_k$. Pi; repeat flag[i] := true; while flag [j] or flag[k] do case turn of j: if flag [j] then begin flag ... in which a waiting process can never enter the critical section? If so, explain and suggest modifications to the code to solve this problem

Consider the following scheme for implementing a critical section in a situation with three processes $P_i, P_j$ and $P_k$.Pi;repeat flag[i] := true; while flag [j] or fl...

go_editor

2.1k views

go_editor asked Apr 18, 2016

2 votes

2 answers

383

MadeEasy Test Series: Operating System - Process Synchronization
Description of Peterson's Algorithm & also for which problem it is used to solve (1) deadlock (2) mutual exclusion (3) Thrashing (4) Paging.

Description of Peterson's Algorithm & also for which problem it is used to solve(1) deadlock(2) mutual exclusion(3) Thrashing(4) Paging.

Jitendra Verma

3.1k views

Jitendra Verma asked Mar 11, 2016

112 votes

7 answers

384

GATE CSE 2016 Set 1 | Question: 50
Consider the following proposed solution for the critical section problem. There are $n$ processes : $P_0....P_{n-1}$. In the code, function $\text{pmax}$ ... in the critical section at any time The bounded wait condition is satisfied The progress condition is satisfied It cannot cause a deadlock

Consider the following proposed solution for the critical section problem. There are $n$ processes : $P_0....P_{n-1}$. In the code, function $\text{pmax}$ returns an inte...

Sandeep Singh

47.5k views

Sandeep Singh asked Feb 12, 2016

42 votes

8 answers

385

GATE CSE 2016 Set 2 | Question: 48
Consider the following two-process synchronization solution. ... synchronization solution. This solution violates mutual exclusion requirement. This solution violates progress requirement. This solution violates bounded wait requirement.

Consider the following two-process synchronization solution.$$\begin{array}{l|l}\hline \text{PROCESS 0 } & \text{Process 1 }\\ \\ \text{Entry: loop while (turn == 1);...

Akash Kanase

15.1k views

Akash Kanase asked Feb 12, 2016

9 votes

2 answers

386

Does Deadlock imply no Bounded waiting Or no Progress or BOTH of These?
Does Deadlock imply no Bounded waiting Or no Progress or BOTH of These?Also provide explanation in support

Does Deadlock imply no Bounded waiting Or no Progress or BOTH of These?Also provide explanation in support

Anurag_s

6.8k views

Anurag_s asked Jan 30, 2016

5 votes

3 answers

387

Synchronization of two processes using Binary Semaphore_2n_EDITION_HARRIS
Suppose we want to synchronize two concurrent processes P and Q using binary semaphores S, T and U: Process P: Process Q: P(S) W: P(T) X: P(U) Y: Print ‘a’ Print ‘a’; Print ‘b’ Print &lsquo ... above problem? (a) P(S), P(T) (b) P(T), P(U) (c) P(S), P(U) (d) None

Suppose we want to synchronize two concurrent processes P and Q using binary semaphores S, T and U:Process P: Process Q:P(S) ...

Purple

1.8k views

Purple asked Jan 29, 2016

3 votes

3 answers

388

Progress guaranteed/Mutual Exclusion/Deadlock or not?
var occupied var blocked Enter Region: { If (occupied) { then blocked= blocked +1 sleep ( ); } else occupied= 1; } Exit Region: { occupied= 0 If (blocked) { then wakeup (process); blocked= blocked – 1; } } True/False (1) Mutual Exclusion is guaranteed? (2) Deadlock free Algorithm? (3) Progress is guaranteed?

var occupiedvar blockedEnter Region:{If (occupied) {then blocked= blocked +1sleep ( );}else occupied= 1;}Exit Region:{occupied= 0If (blocked) {then wakeup (process);block...

Purple

2.3k views

Purple asked Jan 29, 2016

1 votes

3 answers

389

Deadlock vs. Mutual Xclusion
S1. All synchronisation mechanisms that Do not Prevent Deadlock, guarantee mutual exclusion. S2. All synchronisation mechanisms that guarantee mutual exclusion and prevent deadlock will prevent starvation. a) s1 is only correct statement b) s2 is only correct statement c) both are correct d) none of these

S1. All synchronisation mechanisms that Do not Prevent Deadlock, guarantee mutual exclusion.S2. All synchronisation mechanisms that guarantee mutual exclusion and prevent...

Aspi R Osa

518 views

Aspi R Osa asked Jan 21, 2016

0 votes

2 answers

390

synchronisation
The above synchronisation procedure satisfies 1. Mutual exclusion is guranteed 2.Progress is not guranteed 3.Bounded wait is not guranteed 4Deadlock may occur I am getting all of the above. Is it correct?

The above synchronisation procedure satisfies 1. Mutual exclusion is guranteed2.Progress is not guranteed3.Bounded wait is not guranteed4Deadlock may occur I am getting a...

chat28

699 views

chat28 asked Jan 15, 2016

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