NET 424: REAL-TIME SYSTEMS (Practical Part) Networks and Communication Department Tutorial 8: on lecture 6

Question 1 Consider the Priority Ceiling Protocol. Using this protocol, give a picture describing a run of three tasks on one processor: _ Task 1 has the highest priority. Task 1 arrives at time t=6. Task 1 consists of normal computation for 2 time units, followed by critical section 1 for 2 time units, followed by normal computation for 1 time unit. _ Task 2 has lower priority than Task 1. Task 2 arrives at time t=2. Task 2 consists of normal computation for 1 time unit, followed by critical section 2 for 3 time units, followed by normal computation for 1 time unit, followed by critical section 3 for 1 time unit, followed by normal computation for 1 time unit. . Networks and Communication Department

Question 1 _ Task 3 has the lowest priority. Task 3 arrives at time t=0. Task 3 consists of normal computation for 1 time unit, followed by critical section 3 for 2 time units, followed by normal computation for 1 time unit. Your picture should depict which task is executed (and the type of computation: either normal or the critical section the task is in) in the processor at which point in time, covering the interval from time t=0 until all work is done. You should also explicitly give any changes in the priority of the Tasks Networks and Communication Department

Answer R1 R1 T1 R2 R2 R2 R3 T2 R3 R3 T3 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Networks and Communication Department

Question 2 Basic inheritance protocol Ri ei Resource requirements   Ri ei Resource requirements J1 7 3 [R1; 1] J2 5 3 [R2; 1] J3 4 2 J4 2 6 [R1; 4 [R2; 1.5]] J5 0 6 [R2; 4] T=1  J5  R2 T=3  J4  R1 T=11 J4  R2 T=11 J1 R1 T= 13 J2 R2 Networks and Communication Department

Answer R1 J1 R2 J2 J3 R1 R1 R1 R1 R2 J4 R2 R2 R2 R2 J5 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Networks and Communication Department

The End Any Questions ? Networks and Communication Department