A certain computation generates two arrays a and b such that a[i]=f(i) for 0?i

Question

A certain computation generates two arrays a and b such that a[i]=f(i) for 0?i<n and b[i]=g(a[i]) for 0?i<n. It is decomposed into two concurrent processes X and Y: X computes a and Y computes b. They employ two binary semaphores R and S, both initialized to zero. Array a is shared. The process structures are:

```text
Process X:                         Process Y:
private i;                         private i;
for (i = 0; i < n; i++) {          for (i = 0; i < n; i++) {
    a[i] = f(i);                       EntryY(R, S);
    ExitX(R, S);                       b[i] = g(a[i]);
}                                  }
```

Which one of the following represents the CORRECT implementations of ExitX and EntryY?

Accepted Answer

C. ExitX(R,S) { P(S); V(R); }
EntryY(R,S) { V(S); P(R); }

Related Operating Systems PYQs

Turn practice into measurable progress