Test: Process Synchronization- 1 - Computer Science Engineering (CSE) MCQ
15 Questions MCQ Test - Test: Process Synchronization- 1
Consider the following code fragment:
if (fork() == 0)
{ a = a + 5; printf("%d,%dn", a, &a); }
else { a = a –5; printf("%d, %dn", a, &a); }
Let u, v be the values printed by the parent process, and x, y be the values printed by the child process. Which one of the following is TRUE?
if (fork() == 0)
{ a = a + 5; printf("%d,%dn", a, &a); }
else { a = a –5; printf("%d, %dn", a, &a); }
Three concurrent processes X, Y, and Z execute three different code segments that access and update certain shared variables. Process X executes the P operation (i.e., wait) on semaphores a, b and c; process Y executes the P operation on semaphores b, c and d; process Z executes the P operation on semaphores c, d, and a before entering the respective code segments. After completing the execution of its code segment, each process invokes the V operation (i.e., signal) on its three semaphores. All semaphores are binary semaphores initialized to one. Which one of the following represents a deadlockfree order of invoking the P operations by the processes?
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The atomic fetch-and-set x, y instruction unconditionally sets the memory location x to 1 and fetches the old value of x in y without allowing any intervening access to the memory location x. consider the following implementation of P and V functions on a binary semaphore .
void P (binary_semaphore *s) {
unsigned y;
unsigned *x = &(s->value);
do {
fetch-and-set x, y;
} while (y);
}
void V (binary_semaphore *s) {
S->value = 0;
}
Which one of the following is true?
unsigned y;
unsigned *x = &(s->value);
do {
fetch-and-set x, y;
} while (y);
}
S->value = 0;
}
A shared variable x, initialized to zero, is operated on by four concurrent processes W, X, Y, Z as follows. Each of the processes W and X reads x from memory, increments by one, stores it to memory, and then terminates. Each of the processes Y and Z reads x from memory, decrements by two, stores it to memory, and then terminates. Each process before reading x invokes the P operation (i.e., wait) on a counting semaphore S and invokes the V operation (i.e., signal) on the semaphore S after storing x to memory. Semaphore S is initialized to two. What is the maximum possible value of x after all processes complete execution?
At a particular time of computation, the value of a counting semaphore is 7. Then 20 P operation and x V operations were completed on this semaphore. If the final value of the semaphore is 5, x will be
Three processes arrive at time zero with CPU bursts of 16, 20 and 10 milliseconds. If the scheduler has prior knowledge about the length of the CPU bursts, the minimum achievable average waiting time for these three processes in a non-preemptive scheduler (rounded to nearest integer) is _____________ milliseconds.
What is the name of the technique in which the operating system of a computer executes several programs concurrently by switching back and forth between them?
On a system using non-preemptive scheduling, processes with expected run times of 5, 18, 9 and 12 are in the ready queue. In what order should they be run to minimize wait time?
Which of the following conditions does not hold good for a solution to a critical section problem ?
In a dot matrix printer the time to print a character is 6 m.sec., time to space in between characters is 2 m.sec., and the number of characters in a line are 200. The printing speed of the dot matrix printer in characters per second and the time to print a character line are given by which of the following options?
For switching from a CPU user mode to the supervisor mode following type of interrupt is most appropriate
The following C program
main()
{
fork() ; fork() ; printf ("yes");
}
If we execute this core segment, how many times the string yes will be printed ?
Which of the following need not necessarily be saved on a context switch between processes?
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