ExecutionTimeConstraint : public class
Created: 2010-02-01 16:34:33
Modified: 2010-04-30 09:56:25
Project:
Advanced:
<p>ExecutionTimeConstraint expresses the execution time of a function under the assumption of a nominal CPU that executes 1 "function second" per second. Function allocation will decide the actual execution time by multiplication with the relative speed of the host CPU.<br/></p><p><br/></p><p>Example:<br/></p><p><br/></p><p>The ECU is 20% faster than a standard ECU (e.g. in a certain context, execution times are given assuming a nominal speed of 100 MHz; Our CPU is then 120 MHz)<br/></p><p><br/></p><p>The function is activated by a time trigger or a port trigger. The function starts execution some time after activation, depending on e.g. interference and/or blocking from other functions on the same resource.<br/></p><p><br/></p><p>Immediately on start, the function reads input data on all ports. Functions write data at the latest when the execution time has elapsed (which is after the execution time plus any blocking and interference time). <br/></p><p><br/></p><p><br/></p><p>Constraints:<br/></p><p>[1] An ExecutionTimeConstraint either identifies a FunctionType or a FunctionPrototype as its target function.<br/></p><p>[2] variation shall be a value between 0 and upper-lower.<br/></p><p><br/></p><p>Semantics:<br/></p><p>lower (from TimingConstraint) denotes the minimal best case execution time.<br/></p><p>upper (from TimingConstraint) denotes the maximal worst case execution time.<br/></p><p>variation denotes the allowed variation in execution time, i.e. maximal minimal execution time.<br/></p><p><br/></p><p>Example:<br/></p><p>lower=5<br/></p><p>upper=10<br/></p><p>variation=2<br/></p><p>best case execution time of 6 and worst case of 7 is within this constraint<br/></p><p>best case execution time of 6 and worst case of 9 violates this constraint<br/></p><p><br/></p><p>If a measured value is characterized, variation is not used, as it is always upper-lower, e.g. lower=6 and upper=9 above. In this example, the ExecutionTimeConstraint would be a Realization of a VVActualOutcome.<br/></p><p><br/></p>
Element Source Role Target Role Details
Mode
Class  
Name:  
 
Name: mode
 
 
DesignFunctionPrototype
Class  
Name:  
 
Name: targetDesignFunctionPrototype
Identifies the DesignFunctionPrototype with this execution time, and may be used when the constraint applies to a prototype.
 
DesignFunctionType
Class  
Name:  
 
Name: targetDesignFunction
Identifies the DesignFunction with this execution time.
 
Element Source Role Target Role Details
TimeDuration
Class  
Name: variation
Denotes the allowed variation in execution time, i.e. between minimal and maximal execution time.
Name:  
 
 
Object Type Connection Notes
TimeDuration Class Strong