Process	Burst Time	Priority	Arrival Time
P1	8	2	0
P2	5	3	6
P3	1	1	8
P4	2	5	9
P5	6	4	10

Problem1 (40 pts)

Consider the following set of processes, with the length of the CPU burst times given in milliseconds:

1. Draw four Gantt charts illustrating the execution of the processes using FCFS, Preemptive SJF, a non-preemptive priority, and a RR (quantum=2) scheduling. (30 pts)

Note: for the RR consider that the arriving time is 0 for all processes

2. What is the average waiting time of each process for of the above scheduling algorithms? (10 pts)

	P1	P2	P3	P4	P5	Average
FCFS
SJF
Priority
RR

Problem2 (40 pts)

Given 3 concurrent processes P1, P2 and P3, we suppose that initially the shared variable x =4.

1. List all the possible values for x. (15 pts)

2. Use one or more semaphores (use primitives signal and wait) in order to get x=13. ( 15 pts)

3. Can we use only one semaphore to get x=11? Explain your answer. (10 pts)

P1	P2	P3
; x++;	x =x-2; .	x=x*3;

Problem3 (20 pts)

In the Dining-Philosophers Problem explained in the class, one possible solution to avoid the deadlock problem is to use an asymmetric solution (An odd philosopher picks up first her left chopsticks and even philosopher picks up her right chopstick and then right).

Describe this solution using a pseudo-code algorithm assuming that a variable x represent a philosophers position (x can range from 0 to 4).