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Dependable Component Based Software for CE Devices. Robocop & Space4U Experiences Tutorial at ICCE 2006. Fault Management. Trading & Deployment. Terminal Management. Download. Analysis & Integration. Robocop Component. Resource Model. Simulation Model. Service. ….

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Dependable Component Based Software for CE Devices

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Dependable component based software for ce devices

Dependable Component Based Softwarefor CE Devices

Robocop & Space4U Experiences

Tutorial at ICCE 2006


Outline

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 TutorialICCE – 2006page 2 of ???


Performance prediction framework joint work with m r v chaudron

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 TutorialICCE – 2006page 3 of ???


Real time property prediction abstract example

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 TutorialICCE – 2006page 4 of ???


Application domains

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 TutorialICCE – 2006page 5 of ???


Case study mpeg decoder

  • 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 TutorialICCE – 2006page 6 of ???


Performance prediction approach 1 2

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 TutorialICCE – 2006page 7 of ???


Performance prediction approach 2 2

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 TutorialICCE – 2006page 8 of ???


Characteristics of models

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 TutorialICCE – 2006page 9 of ???


Behaviour and resource models

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 TutorialICCE – 2006page 10 of ???


Composing mpeg4 decoder assembly out of selected services

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 TutorialICCE – 2006page 11 of ???


Specifying scenario model

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 TutorialICCE – 2006page 12 of ???


Composing the models 1 3

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 TutorialICCE – 2006page 13 of ???


Composing the models 2 3

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 TutorialICCE – 2006page 14 of ???


Composing the models 3 3

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 TutorialICCE – 2006page 15 of ???


Simulation and analysis 1 2

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 TutorialICCE – 2006page 16 of ???


Simulation and analysis 2 2

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 TutorialICCE – 2006page 17 of ???


Validation against requirements

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 TutorialICCE – 2006page 18 of ???


Not mentioned facilities and benefits

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 TutorialICCE – 2006page 19 of ???


Framework deployment issues

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 TutorialICCE – 2006page 20 of ???


Rtie graphical composer

RTIE Graphical Composer

Robocop & Space4U TutorialICCE – 2006page 21 of ???


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