Exercise Set 2

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Exercise Set 2

• Methods of Design for Embedded Systems

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Exercise 1

• Explain what is the tradeoff between optimality
  and predictability in a RTS

The goal in RTS is to make them as predictable as
possible. However, making the system highly
predictable may require an excessive amount of
computation. On the other hand, we can make the
system response more optimal (lower mean
tardiness) at the expense of being less
predictable.
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Exercise 2

• A) Show a utility function of a hard RT, which
  produces catastrophic consequences when a
  deadline is not met.

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-1
4
Exercise 2

• B) Show the utility function of a soft RTS where
  the early completion of an action is
  counterproductive and after missing the deadline
  the action be somewhat useful.

1
-1
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Exercise 3

• Use the rate monotonic scheduling analysis to
  determine if the following system of tasks Ji is
  schedulable. (Ciexecution time, Tiperiod). All
  tasks are available for executon at t0. Show the
  schedule and indicate change to make it
  schedulable

U1/42/52/7(355640)/140131/140.93 L3(21/3-
1)0.78 therefore LltU and system is not
schedulable
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Exercise 3

• Use the rate monotonic scheduling analysis to
  determine if the following system of tasks Ji is
  schedulable. (Ciexecution time, Tiperiod). All
  tasks are available for executon at t0. Show the
  schedule and indicate changes to make it
  schedulable

If T38 U1/42/52/8(101610)/4036/400.9.
Still L lt U but schedule
Missed deadline
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Exercise 4

• Use EDF algorithm to find the schedule for Ji
  tasks (aistarting time, Ciexecution time,
  dideadline). Assume all tasks have a period of
  10. Determine if it is schedulable.

Its schedulable, because all deadlines are met