Question

1. Assume several processes are running concurrently on a single processor system. Assume also that at time 2, P1 is running, no system resources (other than the CPU and memory) are being used, and that no process is in a blocked state waiting for an event to occur. Consider the following events:
   • At time 3: P1's time slice expires
   • At time 6: P2 is dispatched and given the CPU
   • At time 7: P2 executes a command to read from disk unit 1
   • At time 11: P2 is swapped out to disk
   • At time 15: P3 is dispatched and given the CPU
   • At time 18: An interrupt occurs from disk unit 1: P2's read is complete

   Assuming a process model that includes blocked, suspend ready, and suspend waiting states:

   1. At time 3, what state does P1 enter?
   2. At time 6, what state does P2 enter?
   3. At time 7, what state does P2 enter?
   4. At time 11, what state does P2 enter?
   5. At time 15, what state does P3 enter?
   6. At time 18, what state does P2 enter?

Answer 1

This question follows the 7 state process diagram.

a)

When the time slice for P1 expires, the process goes from RUNNING to READY state.

b)

At time 6, P2 goes from READY to RUNNING state.

c)

At time 7, P2 goes from RUNNING to WAITING state.

d)

At time 11, P2 goes from WAITING to WAITING SUSPEND state.

e)

At time 15, P3 goes from READY to RUNNING state.

f)

At time 18, P2 goes from WAITING SUSPEND to WAITING READY state.