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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">

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	<title>System Schedules</title>
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<h2><u><font color="#336699">System Schedule</font></u></h2>

<p>A <i>System Schedule</i> collects the schedules for all involved resources in the associated
<i><a href="allocations.html">Allocation</a></i> that defines the mapping of the elements
of a <i><a href="task_architecture.html">Task Architecture</a></i>
to the underlying hardware <i><a href="platform_architecture.html">Platform Architecture</a></i>).
An important attribute of a system schedule is its Major Frame (MAF) that is defined as the period of time to be
considered when computing the task allocation and scheduling. The MAF of a <i>System Schedule</i>
is normally equal to the least-common multiple (LCM) of the periods of all
<i>ResourceSchedule</i>s, but can be less than this value under certain conditions such
as harmonicity or geometricity of periods.</p>

<p>The schedule of each individual resource is described using a <i>Resource Schedule</i>.
The allocation of a share of the resource referenced by a <i>Resource Schedule</i> is
expressed using a <i>Resource Allocation</i>.</p>

<p>The AutoFOCUS3 schedule model enables to describe hierarchical schedules. The share of a resource
described by a <i>Resource Allocation</i> allocated in a <i>Resource Schedule</i> can be
further sub-divided by declaring a <i>Sub Schedule</i> for it. <i>Sub Schedule</i>s apply the
concept recursively, i.e., they also contain <i>Resource Allocation</i>s that reference a
<i>SchedulableEntity</i> and a <i>Trigger</i>. A <i>Sub-Schedule</i> does however not
reference a platform resource, since it refines another <i>Resource Allocation</i>. <i>Trigger</i>s
 specify the temporal activation pattern of <i>Resource Allocation</i>s.</p>

<p>The figure below shows the Gantt chart of an exemplary schedule.</p>

<img src="pictures/System.Schedule.Example.png" />

<p>Due to the inherent complexity of the problem, (real-time) schedules are typically not defined manually,
but are <a href="../dse/schedule_synthesis.html">synthesized automatically</a>. To enable comfortable
testing, the modeling perspective of AutoFOCUS3 provides a minimal schedule editor that is based on
the model navigator and the properties section. This means that <i>system schedules</i> can be created using
the context menu of the project, <i>resource schedules</i> can be added in the context
menu of a <i>system schedule</i>, etc.</p>

<img src="pictures/System.Schedule.Edit.Manually.png" />

<p>To view a Gantt chart of a system schedule in the modeling perspective, the </i>Schedule View</i>
needs to be activated from the dialog that is shown by hitting <tt>ALT+SHIFT+Q</tt> followed by <tt>Q</tt>.
The view will render the system schedule that has been selected last in the model navigator.</p>

<img src="pictures/System.Schedule.Show.View.png" />
  
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