Past Exams

RTS Exam WS 2014/2015

• The questions he asked maybe tricky, but the answer most of the time is simple.

• Prof. will draw a table for you. First row is properties, first column is the name of task.

• What should I know before I schedule a real-time systems?

• Hint: Number of CPU, preemptable, period, deadline, WCET, Utilisation

• What is utilisation? Explain to me.

• He will give you the period, WCET and Deadline of each task

• Calculate the utilisation of each task

• After you calculate the utilisation, he will ask you these tasks are schedulable or not?

• Hint: Single processor cannot, but multiple processors can.

• If you have 2 processor how can you schedule these tasks?

• Hint: Dispatch these tasks into different processor

• He will spilt the tasks for you, and tell him how to schedule.

• Hint: Use EDF or RM

• He will question you more details, and make sure you fully understand EDF and RM

• Hint: In RM, there is Harmonic Task, the schedule utilisation is 1

• Then he will ask you which 2 chapters you don't want to be asked.

• Most of time he will jump to hardware, then the question is about Cache Colouring (basic idea of it).

• Hint: [Youtube: Virtual Memory: 6 Address Translation ] explained the basic of cache and virtual address, it can help you to understand the cache colouring.

• Last topic for me is CAN bus. Explain the CAN bus bitwise arbitration

• Tricky question: if one node always send message, what will happen to the bus?