Consider the following policies for preventing deadlock in a system with mutually exclusive resources.

$$\,\,\,\,\,\,\,{\rm I}.$$ $$\,\,\,\,\,\,$$ Processes should acquire all their resources at the beginning of execution. If
$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ any resource is not available, all resources acquired so far are released
$$\,\,\,\,\,{\rm II}.$$ $$\,\,\,\,\,\,$$ The resources are numbered uniquely, and processes are allowed to request
$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ for resources only in increasing resource numbers
$$\,\,\,{\rm III}.$$ $$\,\,\,\,\,\,$$ The resources are numbered uniquely, and processes are allowed to request
$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ for resources only in decreasing resource numbers
$$\,\,\,{\rm IV}.$$ $$\,\,\,\,\,\,$$ The resources are numbered uniquely. A process is allowed to request only
$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ for a resource with resource number larger than its currently held resources

Which of the above policies can be used for preventing deadlock?

Consider the procedure below for the Producer-Consumer problem which uses semaphores:

semaphore n = 0;
semaphore s = 1;
void producer()
{
    while(true)
    {
     produce();
     semWait(s);
     addToBuffer();
     semSignal(s);
     semSignal(n);
    }
}

void consumer()
{
   while(true)
   {
    semWait(s);
    semWait(n);
    removeFromBuffer();
    semSignal(s);
    consume();
   }
}

Which one of the following is TRUE?

An operating system uses the Banker’s algorithm for deadlock avoidance when managing the allocation of three resource types X, Y, and Z to three processes P0, P1, and P2. The table given below presents the current system state. Here, the Allocation matrix shows the current number of resources of each type allocated to each process and the Max matrix shows the maximum number of resources of each type required by each process during its execution. There are 3 units of type X, 2 units of type Y and 2 units of type Z still available. The system is currently in a safe state. Consider the following independent requests for additional resources in the current state:

REQ1: P0 requests 0 units of X, 0 units of Y and 2 units of Z
REQ2: P1 requests 2 units of X, 0 units of Y and 0 units of Z

Which one of the following is TRUE?

A system has n resources R₀,.....,R_n-1, and k processes P₀,.....,P_k-1. The implementation of the resource request logic of each process P_i, is as follows:

if (i%2==0) {
  if (i < n) request Ri;
  if (i+2 < n) request Ri+2 ;
}
else {
  if (i < n) request Rn-i;
  if (i+2 < n) request Rn-i-2;
}

In which one of the following situations is a deadlock possible?