Quiz 2 solutions

1. In the diagram of process states, a CPU-bound process transitions repeatedly between which states?

   CPU-bound means you are primarily switching repeatedly between ready and running. The waiting state involves waiting on an I/O operation. In the ready state, you’re waiting only for the CPU.

2. Schedule the following processes using first-come, first-served (FCFS). Use batch scheduling (no timer). Pay close attention to arrival times; a process cannot start before its arrival time.

   Process  Arrival Time  CPU Time
    P1        0             3
    P2        0             5
    P3        2             2
    P4        8             6
   
     P1    P2    P3    P4
   +-----+-----+-----+-----+
   0     3     8     10    16

3. Compute the average turn-around time of the four processes on your FCFS schedule in the previous question.

   P1:  3 - 0 = 3
   P2:  8 - 0 = 8
   P3: 10 - 2 = 8
   P4: 16 - 8 = 8  Sum = 27. Avg = 27 ÷ 4 = 6.75

4. Now schedule the same four processes using shortest job first (SJF) and compute turn-around time. You must still pay attention to the arrival time!

     P1    P3    P2    P4
   +-----+-----+-----+-----+
   0     3     5     10    16
   
   P1:  3 - 0 =  3
   P2: 10 - 0 = 10
   P3:  5 - 2 =  3
   P4: 16 - 8 =  8  Sum = 24. Avg = 24 ÷ 4 = 6