Part I

1. Explain what memory-mapped I/O is and how it works.
2. Explain what DMA is and how it works.
3. Consider the following set of processes, with the length of the CPU-burst time given in milliseconds:

Process Burst Time Priority

P₁ 8 4

P₂ 1 1

P₃ 2 3

P₄ 1 5

P₅ 6 2

The processes are assumed to have arrived in the order P₁, P₂, P₃, P₄, P₅, all at time 0.

• Draw four Gantt charts illustrating the execution of these processes using FCFS, SJF, a nonpreemptive priority (a smaller priority number implies a higher priority), and RR (quantum = 1) scheduling.
• What is the turnaround time of each process for each of the scheduling algorithms in part 3a?
• What is the waiting time of each process for each of the scheduling algorithms in part 3a?
• Which of the schedulers in part 3a results in the minimal waiting time (over all processes)?

4. A UNIX process has two partsthe user part and the kernel part. Is the kernel part like a subroutine and a coroutine? Why?

Part II

Write a monitor in C++ to simulate the dining philosopher problem mentioned in the textbook using the conditional variables provided by the Pthreads API. Make sure that your implementation is able to handle 5 philosophers and is free of the race condition.