Cheddar 3.3 User Guide

Lab-STICC technical report

Frank Singhoff, Hai Nam Tran, Ill-ham Atchadam, Christian Fotsing, Stéphane Rubini, Mourad Dridi

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Cheddar is a free real time scheduling framework. Cheddar is designed for checking task temporal constraints of a real time application/system. It can also help you for quick prototyping of real time schedulers. Finally, it can be used for educational purpose. Cheddar is a free software, and you are welcome to redistribute it under certain conditions; See the GNU General Public License for details. The Cheddar project was started in 2002 by Frank Singhoff, Lab-STICC Team, University of Brest. Since 2008, Ellidiss technologies also contributes to the development of Cheddar and provides industrial support.

WARNING : this user's guide supposes that you have a minimum background on real-time scheduling. If it's not your case, take a look on this link which includes some very basic articles or book references. This link also provides a description of the analytical methods implemented into Cheddar and gives some publications that show how to use Cheddar.

To completed this user guide, you also have in this technical report , a precise description of all entities used in Cheddar.

• 1. Basic features: scheduling simulation and feasibility tests for independent tasks
  • 1.1 First step : a simple scheduling simulation
  • 1.2 Other available schedulers and task arrival patterns
  • 1.3 Scheduling options
• 2. Cheddar project files (XML and AADL files)
• 3. Cheddar command line

• 4. Scheduling with dependencies

  • 4.1 Shared resources analysis tools
  • 4.2 Task precedencies
    • 4.2.1 Editing Task precedencies
    • 4.2.2 How to transform a dependent task set into an independent task set : the Chetto/Blazewicz modification rules
    • 4.2.3 Computing end to end response time : the Holistic approach
  • 4.3 Buffer analysis tools
  • 4.4 Message scheduling services

• 5. Multiprocessor scheduling services

  • 5.1 Global multiprocessor scheduling
  • 5.2 Cache interference analysis
  • 5.3 Memory interferences analysis
  • 5.4 Network-On-Chip interferences analysis
  • 5.5 Partitionning algorithms

• 6. User-defined simulation code : how to run simulations of specific systems

  • 6.1 Defining new schedulers or task activation patterns.

  • 6.2 Examples of user-defined schedulers

    • 6.2.1 Low-level statements versus High-level statements
    • 6.2.2 User-defined scheduler built with User's defined Task Parameters

  • 6.3 Scheduling with user-defined task arrival patterns

  • 6.4 Running a simulation with a user-defined scheduler
  • 6.5 Looking for user-defined properties during a scheduling simulation
  • 6.6 List of predefined variables and available statements for user-defined code

• 7. Using Cheddar within OSATE 2

  • 7.1 How to install Cheddar plugin within OSATE 2
  • 7.2 Cheddar plugins simple example of use
  • 7.3 Cheddar AADL properties

• 8. Hierarchical scheduling

  • 8.1 ARINC 653 scheduling
    • 8.1.1 How to model an ARINC 653 two-levels scheduling
    • 8.1.2 Example of an ARINC 653 scheduling
  • 8.2 Aperiodic server hierarchical scheduling

• 9. MILS and security services