Page 118 - DCAP608_REAL TIME SYSTEMS

Unit 11: Application of Clock-driven Scheduling

 A reasonable way to schedule a mode-change job that has a soft deadline is to treat it just Notes
like an ordinary aperiodic job, except that it may be given the highest priority and executed
ahead of other aperiodic jobs.
 Searching for a feasible multiprocessor schedule is more complex than searching for a
uniprocessor schedule.

 Dataflow models are widely used to represent DSP applications.
 A synchronous dataflow graph (SDFG) is a finite directed graph G = ,V,E,t,d, prd, cns>, in
which V is the set of actors, modelling the functional elements of the system; E is the set of
directed edges, modelling interconnections between functional elements.

11.5 Keywords

DSP Algorithms: Digital signal processing (DSP) is the mathematical manipulation of an
information signal to modify or improve it in some way.
Iteration Period: The average computation time per iteration is called the iteration period of a
schedule.
Iteration: Execution of all the computations for the required number of times is referred to as
iteration.

Rate-optimal Schedule: A schedule whose iteration period equals the iteration bound is called
a rate-optimal schedule.
Synchronous Dataflow Graph: Data flow programs for signal processing are directed graphs
where each node represents a function and each arc represents a signal path.

11.6 Review Questions

1. Discuss the ways or methods to handle overrun.
2. What do you mean by frame overrun?

3. Explain the concept of Aperiodic Mode Change.
4. Elucidate the importance of mode changes in frame overruns.
5. Give an overview on Pros and Cons of Clock-Driven Scheduling.
6. Describe the concept of Algorithm for Constructing Static Schedules.
7. Throw light on synchronous dataflow graph.

Answers: Self Assessment

1. Software flaw 2. Overrun
3. Sporadic job 4. Periodic task
5. DSP algorithms 6. Explicit or implicit
7. HSDFG 8. Iteration period

9. Static schedule 10. False
11. False 12. True

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