1. Gabor Madl (gabe@ics.uci.edu) Nikil Dutt (dutt@ics.uci.edu)
Domain-specific Modeling of Power Aware Distributed Real-time Embedded Systems
Gabor Madl
Nikil Dutt
Embedded Computer Systems: Architectures, Modeling, and Simulation (SAMOS) 2006 Workshop
November 12, 2018

2. Outline Motivation Proposed analysis framework
Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
Outline
Motivation
Proposed analysis framework
The open-source DREAM tool
The ALDERIS language
Specification by meta-modeling
XML representation of ALDERIS
Helicopter autopilot case study
Analysis results
Conclusion
November 12, 2018

3. Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
DRE systems are often reactive, and event-driven
Better latencies than synchronous or time-triggered models
Easy implementation
In DRE systems classic scheduling methods may result in scheduling anomalies
Hard to analyze real-time properties
We need a method that can capture the behavior of DRE systems
Continuous time
Multiple QoS properties
November 12, 2018

4. Proposed analysis framework
Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
Proposed analysis framework
ALDERIS model GME tool
Open-source DREAM Tool
Simulations
Random testing
Schedulability optimizations
Automatic timed automata model generation for the UPPAAL and Verimag IF tools
Simulation-based model checking
Verimag IF model checker
Focus of my presentation
ALDERIS model XML representation
UPPAAL model checker
November 12, 2018

5. Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
The ALDERIS language
ALDERIS is a modeling language with both a visual and a textual XML-based syntax
ALDERIS specifies two aspects of a DRE system
The dependency aspect
Based on an abstract task model
Explicitly captures dependencies between tasks
Each task is attributed by a [bcet, wcet] execution interval, and a sub-priority
The platform aspect
Threads schedule tasks non-preemptively, have priorities
Between threads preemptive scheduling within CPUs
November 12, 2018

6. Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
The ALDERIS language
Timers generate events periodically
Sensors sampled at a given rate
Event channel model
Provides buffering
May specify delays using an interval
ALDERIS seems to be a good fit to analyze the real-time properties of globally asynchronous locally synchronous (GALS) systems.
November 12, 2018

7. Specification by meta-modeling
Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
Specification by meta-modeling
ALDERIS is specified using meta-modeling (GME tool)
We use domain-specific modeling languages (DSMLs) instead of generic modeling languages such as UML
Meta-modeling defines
Abstract syntax
Concrete syntax
But not semantics
November 12, 2018

8. XML representation of ALDERIS
Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
XML representation of ALDERIS
<?xml version="1.0" encoding="UTF-8"?>
<DRESystem xmlns:xsi="
xsi:noNamespaceSchemaLocation="alderis.xsd" name="helicopter autopilot" version="1.0">
<DependencyAspect>
<Node>
<Task name="Gyro" bcet=“2” deadline=“5" subpriority="1" wcet=“3"/>
...<Channel name="Gyro Channel" buffersize="2"/>
...<Timer name="Gyro Rate" period="5"/>
</Node>
<Hierarchy>
<Component name="INS">
<TaskContainment task="INS Task"/>
</Component>
...</Hierarchy>
<Dependency>
<TimerToTask timer="Gyro Rate" task="Gyro"/>
...<TaskToChannel task="Gyro" channel="Gyro Channel"/>
...<ChannelToTask channel="Gyro Channel" task="Tail Servo"/>
...</Dependency>
</DependencyAspect>
<PlatformAspect>
<Thread name="Control Thread" priority="1" queueingpolicy="FixedPriority">
<TimerMapping timer="INS Rate"/>
<ComponentMapping component="INS"/>
...</Thread>
<CPU name="Main CPU" schedulingpolicy="FixedPriority">
<QoSLevel speed="2" power="4"/>
...<ThreadMapping thread="Control Thread"/>
...</CPU>
<CPU name="NonConcurrentManager" schedulingpolicy="NonConcurrent">
<ThreadMapping thread="NonConcurrent"/>
</CPU>
</PlatformAspect>
</DRESystem>
November 12, 2018

9. Helicopter autopilot case study
Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
Helicopter autopilot case study
Several problems in helicopters
Internal navigation system
Cyclic/collective pitch
Mechanical
Aerodynamic
ALDERIS can be used to
Formally verify real-time properties
Synthesize a task-level power management policy
November 12, 2018

10. Helicopter autopilot case study
Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
Helicopter autopilot case study
Based on a UAV design from the CoSMIC toolset from Vanderbilt University
Dependency and platform aspects are shown
Components express hierarchy
Components are not active objects
Encapsulate methods that provide similar functionality
November 12, 2018

11. (Figure from the UPPAAL model checker)
Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
Real-time Analysis
(Figure from the UPPAAL model checker)
November 12, 2018

12. Power Management Task-level power management method
Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
Power Management
Task-level power management method
For real-time systems
Captures voltage scaling
We assume that power = constant*voltage2.
Power level can only be changed at discrete time steps
This allows the use of timed automata models
Decidable power management policy synthesis problem
Based on formal model checking methods we were able to show a potential 24% energy savings
November 12, 2018

13. Outline Motivation DREAM framework ALDERIS Case study Results Conclusion
We have presented the ALDERIS MoC
Formally defined semantics
Captures real-time properties and voltage-scaling in a common semantic domain
We have shown how meta-modeling has been used to define ALDERIS
Can be composed with formal MoCs such as timed automata, hybrid automata, dataflow or Petri-nets
ALDERIS provides a formal approach to analyze and verify DRE systems.
November 12, 2018

14. Questions? Please visit http://dre.sourceforge.net
The open-source DREAM tool and its documentation
Medium to large-scale examples of real-time CORBA applications based on the Boeing Bold Stroke execution framework.
Please visit
GME meta-model of the ALDERIS DSML
Case studies
November 12, 2018