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Dependable Component Based Software for CE Devices

This tutorial at ICCE 2006 focuses on the development of dependable component-based software for CE devices using Robocop and Space4U. It covers topics such as fault management, trading, deployment, terminal management, and performance prediction.

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Dependable Component Based Software for CE Devices

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  1. Dependable Component Based Softwarefor CE Devices Robocop & Space4U Experiences Tutorial at ICCE 2006

  2. Fault Management Trading &Deployment Terminal Management Download Analysis&Integration Robocop Component Resource Model Simulation Model Service … Resource Management Functional Model logic other Middleman logic Executable Component Service Component Model logic Outline Introduction Architecture Component Model Resource Management Fault Management Real-Time Prediction Wrap-Up Robocop & Space4U Tutorial ICCE – 2006 page 2 of ???

  3. Performance Prediction Frameworkjoint work with M.R.V.Chaudron Objectives: • At the design phase • Graphically compose an assembly from components • Predict performance properties of an assembly • Task latencies • Number of missed deadlines • Processor, bus, memory load • Note: without even buying the constituent components! Robocop & Space4U Tutorial ICCE – 2006 page 3 of ???

  4. Stimulus Response Video decoder example: Is Response Time within TMin and TMax? Decoder VLD Inverse Quantizer Inverse DCT …011010101… bit-stream of a frame reconstructed frame Decoding task latency < 40 ms Real-time Property PredictionAbstract example: CompA CompB CompC CompD Robocop & Space4U Tutorial ICCE – 2006 page 4 of ???

  5. Application Domains • Hard real-time systems • Task lateness leads to catastrophic results • anti-lock braking system • air-bag controller • Firm real-time systems • No catastrophic consequences, but value of the function = 0 • car navigation • surveillance camera • Soft real-time systems • Task lateness reduces a value of the function • multimedia, video and audio codecs • electronic game Robocop & Space4U Tutorial ICCE – 2006 page 5 of ???

  6. Given • Remote repository with various components and services Reader Reader Reader Reader FIFO Buffer Reader MPEG4 Decoder Renderer Case Study: MPEG Decoder • Requirements • MPEG4 decoder functionality • Rate of skipped frames <= 1% • Refreshment frequency is 25 frames/sec • Missing deadline for decoding task <= once per 4 sec • Goal: without even buying the components • Assess the performance and timeliness of a designed assembly Robocop & Space4U Tutorial ICCE – 2006 page 6 of ???

  7. Performance Prediction Approach (1/2) The approach is a four-step strategy: • The component developer specifies • behaviour model of a component • resource model of a component • Application developer: • composes selected components/services and • selects scenario of interest & models this scenario (application scenario model) • These three models are compiled together • into a model of the execution architecture (incl. concurrent tasks) • For each scenario the tasks execution is simulated • execution timeline of tasks Robocop & Space4U Tutorial ICCE – 2006 page 7 of ???

  8. Select ! Models Component Resource model Component Resource model has ! Real-time aware components Real-time aware components Component Behaviour model has Component Behaviour model Design (assemble) ! Construct Application Scenario model Real-time application Application Scenario model Compile models / reconstruct tasks Validate predicted for Execution architecture (tasks) Simulate task execution Analyze Real-time and performance properties Task execution timeline Performance Prediction Approach (2/2) Input Application requirements Robocop & Space4U Tutorial ICCE – 2006 page 8 of ???

  9. Characteristics of Models • Reflect the implementation at higher abstraction level • Behaviour model • for each operation specifies a sequence of invocations of operations of other interfaces • Resource model • contains processing, bandwidth and memory usage of each component operation • Application Scenario model: • assembly structure, specific for this scenario • environmental events or system interrupts (task triggers) • Resource, Behaviour and Scenario models are composable • composed model represents an execution architecture (task pool) of a whole application Robocop & Space4U Tutorial ICCE – 2006 page 9 of ???

  10. Behaviour and Resource Models BehavourModel_MPEG4Decoder_Component behaviour operation IDecode.decodeFrame() calls IBufferAccess.getElement() passedBits = 0 returnedBits = 1024 synchronous = TRUE numberOfIterations = 1 calls IBufferAccess.storeElement() passedBits = 1024 returnedBits = 1 synchronous = TRUE numberOfIterations = 1 ResourceModel_MPEG4Decoder_Component resource use operation IDecode.decodeFrame() cpu claim max = 1E7 cycles (reference processor) aver = 1E5 cycles (reference processor) min = 1E4 cycles (reference processor) mem claim = 10 KB mem release = 3 KB IDecode IBufferAccess getElement() decodeFrame() storeElement() Robocop & Space4U Tutorial ICCE – 2006 page 10 of ???

  11. Composing MPEG4 Decoder AssemblyOut of selected services IWrite IRead IDecode vRenderer: Renderer vReader: Reader vDecoder: MPEG4Decoder IBufferAccess IBufferAccess IBufferAccess IBufferAccess IBufferAccess wBuffer: FIFO Buffer rBuffer: FIFO Buffer Robocop & Space4U Tutorial ICCE – 2006 page 11 of ???

  12. Task Trigger Invokes IRead.readFrame() every 40 ms Invokes IWrite.renderFrame() every 40 ms Invokes IDecode.decodeFrame() every 40 ms Task Trigger – can be implemented in glue code as a POSIX thread with periodic events Specifying Scenario Model Processing Node: MIPS 130 IWrite IRead IDecode vRenderer: Renderer vReader: Reader vDecoder: MPEG4Decoder IBufferAccess IBufferAccess IBufferAccess IBufferAccess IBufferAccess wBuffer: FIFO Buffer rBuffer: FIFO Buffer Robocop & Space4U Tutorial ICCE – 2006 page 12 of ???

  13. Models Component Resource model Component Resource model Input has Application requirements Component Behaviour model has Component Behaviour model Design (assemble) Construct Application Scenario model Real-time application Application Scenario model Compile models / reconstruct tasks Validate predicted for Pool of tasks in application Simulate task execution Analyze Real-time and performance properties Task execution timeline Composing the Models (1/3) Robocop & Space4U Tutorial ICCE – 2006 page 13 of ???

  14. TaskTrigger invoke InterfaceX.OperationA period 40 ms offset 0 ms deadline 40 ms Application Scenario Component Behavior Model: Model: OperationA() calls InterfaceZ.OperationB() nmbIterations = 1 InterfaceY.OperationC() Service_B Service_C Service_D Service_F nmbIterations = 1 Task Trigger (period 40 ms) Operation_B Operation_D Operation_E Component Resource Model: Operation_E Operation_E 3ms CPU claim = 30ms Operation_E Operation_C Operation_F Composing the Models (2/3) The generated task specifies • sequence of constituent method invocations • period, deadline, priority, synchronization constraints Service_A Operation_A Robocop & Space4U Tutorial ICCE – 2006 page 14 of ???

  15. Invokes IRead.readFrame() every 40 ms Invokes IWrite.renderFrame() every 40 ms Invokes IDecode.decodeFrame() every 40 ms Composing the Models (3/3) Task Trigger IWrite IRead IDecode vRenderer: Renderer vReader: Reader vDecoder: MPEG4Decoder IBufferAccess IBufferAccess IBufferAccess IBufferAccess IBufferAccess wBuffer: FIFO Buffer rBuffer: FIFO Buffer Robocop & Space4U Tutorial ICCE – 2006 page 15 of ???

  16. Models Component Resource model Component Resource model Input has Application requirements Component Behaviour model has Component Behaviour model Design (assemble) Construct Application Scenario model Real-time application Application Scenario model Compile models / reconstruct tasks Validate predicted for Pool of tasks in application Simulate task execution Analyze Real-time and performance properties Task execution timeline Simulation and Analysis (1/2) Robocop & Space4U Tutorial ICCE – 2006 page 16 of ???

  17. Simulation and Analysis (2/2) • Simulation or Schedulability analysis are performed with scheduling algorithms deployed on the target OS (RMA, EDF, CBS) • Simulation results in task latencies, number of missed deadlines, CPU, memory and bus utilization Simulation time Bus load Mem load Simulation time Simulation time Robocop & Space4U Tutorial ICCE – 2006 page 17 of ???

  18. Validation against Requirements Video Decoding Task: Related REQ: “Skipped frames rate < 1%” • Decision on acceptance of the composed assembly • If “not accept”: try different component configurations, or other components • If “accept”: buy the components, implement application-level glue code, test and deploy Robocop & Space4U Tutorial ICCE – 2006 page 18 of ???

  19. Not mentioned Facilities and Benefits • Modelling of parameter-dependent behaviour and resource usage • Multiple-platform resource models • Task synchronization aspects can be modeled • Component mapping on multiprocessor architecture • Multidimensional design space exploration • robusteness vs cost, memory_load vs cpu_load, etc Robocop & Space4U Tutorial ICCE – 2006 page 19 of ???

  20. Framework Deployment Issues • We have developed a tool chain supporting the design activities • We have validated the prediction approach by MPEG4 Decoder case study: • prediction accuracy of general performance is > 90% • prediction accuracy on task latencies is > 70% Real-Time Prediction Framework Robocop & Space4U Tutorial ICCE – 2006 page 20 of ???

  21. RTIE Graphical Composer Robocop & Space4U Tutorial ICCE – 2006 page 21 of ???

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