Assume that at time 5 no system resources are being used except for the processo

Question

Assume that at time 5 no system resources are being used except for the processor and memory. Now consider the following events:

At time 5: P1 executes a command to read from disk unit 3.

At time 15: P5’s time slice expires.

At time 18: P7 executes a command to write to disk unit 3.

At time 20: P3 executes a command to read from disk unit 2.

At time 24: P5 executes a command to write to disk unit 3.

At time 28: P5 is swapped out.

At time 33: An interrupt occurs from disk unit 2: P3’s read is complete.

At time 36: An interrupt occurs from disk unit 3: P1’s read is complete.

At time 38: P8 terminates.

At time 40: An interrupt occurs from disk unit 3: P5’s write is complete.

At time 44: P5 is swapped back in.

At time 48: An interrupt occurs from disk unit 3: P7’s write is complete.

For time 37, identify which state each process is in. If a process is blocked, further identify the event on which it is blocked.

Explanation / Answer

T = 22: P5, P8 ready/running
P1, P3, P7: blocked for I/O
T = 37: P1, P3, P8: ready/running
P5: blocked suspend (swapped out)
P7: blocked for I/O
T = 47: P1, P3, P5 ready/running
P7: blocked for I/O
P8: exit

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