Real Time Systems - Old Questions

3. A system contains nine non preemptable jobs named J_i, for i = 1,2,...9. The execution times are 4, 3, 3, 3, 5, 5, 5, 5, and 10, respectively, their release times are equal to 0, and their deadlines are 10.J1 is the immediate predecessor of J₉, and J₄ is the immediate predecessor of J₅, J₆, J₇, and J₈. There are no other precedence constraints. For all the jobs, J₁ has a higher priority than J_k if i < k.

a) Draw the precedence graph of the jobs.

b) Can the jobs meet their deadlines if they are scheduled  on three processors?

c) Can the jobs meet their dead lines if made preemptable and schedule them preemptively.