Einführung

Tasks

Tasks can be aperiodic or periodic. Depending on the type a set of task parameters exists which determinate the behavior of the task.

Each task has a execution time c. The execution time is the numbers of time units which the task needs the processor for its execution.

For periodic tasks you can additionally specify a periode p. The period represents the time intervall within each job of a periodic task has to finish its execution. A constant execution time is assumpted for each job of a periodic task.

In addition to the execution time you you can specify an arrival time a and a deadline interval d for aperiodic tasks. The arrival time represents the number of time units after which the task is available. The deadline interval defines the number of time units after which the task have to finish its execution.

For task with resource access you have to assign a priority p. Also you can give a list of resource accesses specified by a resource S and the time values for the access (&Delta t P(S) and &Delta t V(S)).

Within the training module the tasks will be represented by task symbols. The task symbol displays the current parameter values of the task depending of its type. Figure 7 shows the task symbol of an aperiodic task (left hand) and the symbol of a periodic task (right hand). A task symbol of an aperiodic task with resource access is shown in figure 8.

aperiodischer und periodischer Task
Figure 7


Task mit Ressourcenzugriff
Figure 8

The next subsections give more details about the specification of task parameter and you will see how to add or remove a task within scenario editor.

 
Introduction > Tasks

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