Consider a system that uses a state model including suspend ready and suspend waiting states. Assume that at time 1 no system resources are being used except for the processor and memory. Now consider the following events:

At time 2: P1 executes a command to read from disk unit 3

At time 5: P3's time slice expires

At time 8: P4 executes a command to write to disk unit 3

At time 10: P2 executes a command to read from disk unit 2

At time 14: P3 executes a command to write to disk unit 3

At time 18: P3 is swapped out to disk

At time 20: An interrupt occurs from disk unit 2: P2's read is complete

At time 22: An interrupt occurs from disk unit 3: P1's read is complete

At time 26: An interrupt occurs from disk unit 3: P3's write is complete

At time 28: P3 is swapped back in

At time 30: An interrupt occurs from disk unit 3: P4's write is complete

a. At time 12, what are the possible states that P1 could be in? What are the possible states that P2 could be in? P3? P4?

b. At time 23, what are the possible states for each of the processes P1, P2, P3, and P4?

c. At time 27, what are the possible states for each of the processes P1, P2, P3, and P4?

New Activate Dispatch. Release Ready/ Suspend Running Exit Suspend Timeout Activate Blocked/ Suspend Blocked Suspend (b) With Two Suspend States Figure 3.9 Process State Transition Diagram with Suspend States