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VEST: Virginia Embedded Systems Toolkit*

VEST: Virginia Embedded Systems Toolkit*. Professor Jack Stankovic Department of Computer Science University of Virginia October 2001. Supported, in part, by the Darpa PCES program. Outline. Motivation/The Problem Overview of the VEST Tool (A Few) Research Questions

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VEST: Virginia Embedded Systems Toolkit*

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  1. VEST: Virginia Embedded Systems Toolkit* Professor Jack Stankovic Department of Computer Science University of Virginia October 2001 • Supported, in part, by the Darpa PCES program.

  2. Outline • Motivation/The Problem • Overview of the VEST Tool • (A Few) Research Questions • What this tool is NOT! • Summary/Status

  3. Engine control Wristwatch Modems Mobile phone Internet appliances Process Control Air Traffic Control 60 Processors in Limo Smart Spaces Sensor/Actuator/CPU clouds with movable entities Smart dust Embedded Systems

  4. Smart Spaces • Pervasive • Global Connectivity Smart School Smart Classroom Smart City Smart Factory

  5. Key Issue • Enormous numbers of devices and amounts of software needed • flexible and tailored (off-line for some systems; on-line for others) • interaction with physical/distributed environment (of greater heterogeneity - not just cpus) • many constraints • power, mobility, real-time, cost, memory size, ft, etc. • How do we develop, tailor, optimize software for such systems in a cost effective manner?

  6. Solution • domain specific program composition • take embedded systems software from libraries • map to HW (sensors, actuators, CPUs, etc.) • tailor and optimize HW/SW • automate analysis and dependency checks • address hidden dependencies (cross-cutting concerns - aspects)

  7. Program Composition • Goal: building a tool that enables component-based construction and analysis of embedded systems • flexible • tailored • considers • power, mobility, distribution, heterogeneity, wireless, sensors, actuators, scale, performance

  8. What is a Component? • High level components (Corba, DCOM, Java Beans) • reusable, reliable, tailor, dynamic, written by domain experts, … • slow, unpredictable, weak on non-functional properties (performance (real-time), dependability, …), hard to modify • Need - Embedded System Components

  9. How is it different? • Performance concerns such as meeting deadlines; dependability concerns • Physical environment linkage is paramount • Global analysis needed • Not necessarily third party • careful control over library • Domain specific • avionics, smart hospital, ... • Hypothesis: Significant amounts of attached reflective information (dependencies) are needed

  10. Perspective/Design Tools Requirements Design/Design Analysis Synthesis/(Components with Analysis) VEST

  11. VEST Configuration Tool Components Micro-components Infrastructures Configuration Tool Analysis Tools Reflective Infor. Dependencies ASPECTS Dependency Checks Analysis Composition • Factual • Inter-component • Aspects • General • Real- Time • Reliability • Infrastructure • Embedded System

  12. Configuration Tool • Base Libraries • SW • OS • Middleware • Aspects • Domain Code • HW • Infrastructures • Configuration Tool • Browse • Compose • Check • Analysis Tools Product Library Dependency Checks Composition Map to Process Map to HW Analysis • Factual • Inter-component • Aspects • General • Real- Time • Reliability Dependency Checks Dependency Checks

  13. VEST Workspace

  14. Reflection Methodology • Identify the reflective information (semantics) • Retain the information in tools/on disk • Perform dependency checks and analysis based on that information • Retain the information at runtime (flexibility) • Expose the information to the application code

  15. Factual ComponentID Flag: SW/HW HW Power speed reliability size cost accuracy sensitivity range Bus, memory, processors, cache, D/A, A/D, sensor, actuator, co-processor, DSP, Networks Code WCET Memory/Size Data Bandwidth Importance Deadline Security Jitter Power

  16. Inter-component Dependencies Interfaces (parameters and types) Call graph Precedence Requirements Waits for Exclusion requirements Version compatibility Included in

  17. ASPECTS • If it can not be cleanly encapsulated in a generalized procedure • affect the performance or semantics of components • Examples (categories) • end-to-end real-time performance • dependability • security • concurrency and synchronization • optimizations

  18. Examples of Aspects • Logging in Apache Web server • Pre-fetching in OS • Simple embedded system, then add kill primitive • Periodic tasks only, then add aperiodics • Change system to use spin locks • Sizing Message Buffers • Many examples with Concurrency and RT performance

  19. Dependency Checks • From the simple to the complex • Ex. 1: Is there sufficient memory? (factual) • Ex. 2: Are the input parameters of the correct number and type? (inter-component) • Ex. 3: Are interrupts disabled/enabled properly? (aspect) • Ex 4: Is the end-to-end real-time constraint being met? (analysis)

  20. Example: RT Analysis Components/Tasks Platform Components Speed Bandwidth Network protocols WCET D Resources Precedence Composed (Distr) System Mapping Workload Analysis - H() Reflective Information

  21. Research Questions • What are language independent aspects? • Modular constraints (Vanderbilt) • Instructions on how to change or test components • What are the hidden dependencies that exist in real-time and embedded systems; how do we make these dependencies visible • produces an effective methodology? • How to integrate component composition with design time tools

  22. What this tool is NOT • A complete requirements/specification/design tool • rather it concentrates on improving composition of components from embedded systems libraries • No proofs of correctness • avoids common errors, avoids insidious cross cutting errors that can crop up when composing library based components

  23. Summary • Status: • first version of tool is operational • second version to include: • support for objects, events • mapping to active processes and HW • additional aspect checks • being migrated to GME

  24. Reflection - Example PCB - not reflective PCB Reflective registers registers ptr to stack ptr to stack priority priority deadline What it takes to execute! FT requirements part of group

  25. Reflection in RTOS • Enhances visibility of information between levels(off-line to on-line) • FT and RT information • Individual module and system-wide policies Simple Examples 1 1 FT 3 exec. vs 2 2 3 3 Node 1 Node 2 Node 3 T1 = P1; T2 = P2; T3 = P3; System does not know they are related Lost information

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