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

Question 1 A system contains two periodic tasks. They are (10,3) & (15,4). The task system also contains a sporadic server whose period is 8 and budget =2 The sporadic server is scheduled with the periodic tasks rate-monotonically. 1)Suppose that two aperiodic tasks A1 arrives at 2 and has execution time 2 and A2 arrives at 7 and has execution time 2. Find a feasible schedule. Networks and Communication Department

Answer Networks and Communication Department

Question 2 Assume the following periodic tasks: Task Period Deferrable server (7,1). Can we schedule the above tasks using RMS (rate monotonic scheduling)? Task Period Execution time 1 4 2 3 8 0.5 5 Networks and Communication Department

Answer Using : Networks and Communication Department

Answer Testing for T1: 𝟏 𝟒 + 𝟏 𝟕 + 𝟏 𝟒 =𝟎.𝟔𝟒𝟐 < U , So we can schedule T1 𝑼=𝒏 𝟐 𝟏 𝒏 − 𝟏 =𝟔 𝟐 𝟏 𝟔 −𝟏 = 𝟎.𝟕𝟑𝟔 ///n the total number of tasks including the server T2, T3 can also be scheduled because they have the same value for the period and the execution time . Testing for T4: 𝟏 𝟒 + 𝟎.𝟓 𝟖 + 𝟏 𝟕 + 𝟏 𝟖 =0.58 < U so both T4 and T5 can be scheduled Networks and Communication Department

Question 3 Execution time Period Task Assume the following periodic tasks: And a deferrable server (40,10). Can we schedule the above tasks using RMS (rate monotonic scheduling) or EDF (earliest deadline first)? Execution time Period Task 10 50 1 20 60 2 Networks and Communication Department

Answer Using : RMS EDF Networks and Communication Department

Answer 1) RMS Testing for T1: 𝟏𝟎 𝟓𝟎 + 𝟏𝟎 𝟒𝟎 + 𝟏𝟎 𝟓𝟎 =𝟎.𝟔𝟓 < U , So we can schedule T1 𝑼=𝒏 𝟐 𝟏 𝒏 − 𝟏 =𝟑 𝟐 𝟏 𝟑 −𝟏 = 𝟎.𝟕𝟕 ///n the total number of tasks including the server Testing for T2: 𝟏𝟎 𝟓𝟎 + 𝟐𝟎 𝟔𝟎 + 𝟏𝟎 𝟒𝟎 + 𝟏𝟎 𝟔𝟎 =0.95 > U T2 can NOT be scheduled. We can NOT schedule the tasks using RMS. Networks and Communication Department

Answer 2) EDF Calculate T1: 𝟏𝟎 𝟓𝟎 + 𝟐𝟎 𝟔𝟎 + 𝟏𝟎 𝟒𝟎 (𝟏+ 𝟒𝟎−𝟏𝟎 𝟓𝟎 )=0.93<1, So we can schedule T1 Calculate T2: 𝟐𝟎 𝟔𝟎 + 𝟏𝟎 𝟓𝟎 + 𝟏𝟎 𝟒𝟎 (𝟏+ 𝟒𝟎−𝟏𝟎 𝟔𝟎 )=0.905 <1, So we can schedule T2 The tasks can be scheduled using EDF. Networks and Communication Department

The End Any Questions ? Networks and Communication Department