### Modeling Example "Purely Periodic without Communication"

This system architecture pattern consists of a task set, where each task is activated periodically and no data accesses are performed. The execution time for each task is determined by the called runnable entities as specified in the table below. All tasks contain just one runnable except of T7, which calls at first R7,1 and after that R7,2.

The table below gives a detailed specification of the tasks and their parameters. The tasks are scheduled according fixed-priority, preemptive scheduling and if not indicated otherwise, all events are active in order to get a detailed insight into the system’s behavior.

Task | Priority | Preemption | Multiple Task Activation Limit | Activation | Execution Time
--- | --- | --- | --- | --- | ---
T1 | 7 | FULL | 1 | Periodic | R1 | Uniform
Offset = 0 | Min = 9.95
Recurrence = 80 | Max = 10
T2 | 6 | FULL | 1 | Periodic | R2 | Uniform
Offset = 0 | Min = 29.95
Recurrence = 120 | Max = 30
T3 | 5 | FULL | 1 | Periodic | R3 | Uniform
Offset = 0 | Min = 19.95
Recurrence = 160 | Max = 20
T4 | 4 | FULL | 1 | Periodic | R4 | Uniform
Offset = 0 | Min = 14.95
Recurrence = 180 | Max = 15
T5 | 3 | FULL | 1 | Periodic | R5 | Uniform
Offset = 0 | Min = 29.95
Recurrence = 200 | Max = 30
T6 | 2 | FULL | 1 | Periodic | R6 | Uniform
Offset = 0 | Min = 39.95
Recurrence = 300 | Max = 40
T7 | 1 | FULL | 1 |  | R7,1 | Uniform
Min = 59.95
Periodic | Max = 60
Offset = 0 | R7,2 | Uniform
Recurrence = 1000 | Min = 19.95
| Max = 20

In order to show the impact of changes to the model, the following consecutive variations are made to the model:

1) Initial Task Set
  For this variation, the Tasks T4, T5, T6, and T7 of the table above are active.

2) Increase of Task Set Size I
  For this variation, the Tasks T3, T4, T5, T6, and T7 are active. That way the utilization of the system is increased.

3) Increase of Task Set Size II
  For this variation, the Tasks T1, T3, T4, T5, T6, and T7 are active. That way the utilization of the system is increased.

4) Increase of Task Set Size III
  As from this variation on, all tasks (T1 - T7) are active. That way the utilization of the system is increased.

5) Accuracy in Logging
  For this variation, just task events are active. That way, only a limited insight into the system’s runtime behavior is available.

6) Schedule
  As from this variation on, T7 is set to non-preemptive. That way, the timing behavior is changed, which results in extinct activations (see red mark in the figure below).

7) Activation
  As from this variation on, the maximum number of queued activation requests for all tasks is set to 2. That way, the problem with extinct activations resulting from the previous variation is solved.

8) Schedule Point
  For this variation, a schedule point is added to T7 between the calls of R7,1 and R7,2. That way, the timing behavior is changed in particular.

9) Scheduling Algorithm
  For this variation, the scheduling algorithm is set to Earliest Deadline First. That way, the timing behavior is changed completely.