Real-Time Scheduling Author: Peter van der Stok CTT-DRTS-WS - - PowerPoint PPT Presentation

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Real-Time Scheduling Author: Peter van der Stok CTT-DRTS-WS - - PowerPoint PPT Presentation

1 Real-Time Scheduling Real-Time Scheduling Author: Peter van der Stok CTT-DRTS-WS Scheduling dd 5-1-2001 Phi l i ps Res ear ch 2 Real-Time Scheduling Overview Three examples water vessel avionics multimedia


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Phi l i ps Res ear ch

1 Real-Time Scheduling

CTT-DRTS-WS Scheduling dd 5-1-2001

Real-Time Scheduling

Author: Peter van der Stok

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2 Real-Time Scheduling

Overview

  • Three examples

– water vessel – avionics – multimedia streaming

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3 Real-Time Scheduling

Example of RT system: Problem

  • Water vessel problem

– Requirements

  • Water should not overflow
  • Pump should not run dry

– Properties:

  • Positive but limited influx of water when pump is off
  • Positive but limited outflux of water when pump is on
  • Sensors are placed ∆ h from critical levels
  • d time units needed for level change ∆ h

pump water high sensor -- o water low sensor --o ∆ h ∆ h

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4 Real-Time Scheduling

Example of RT system: Solution

– Critical conditions should not exist longer than d without response

  • critical conditions C: water above/below sensor

– Periodic task is released with period T and satisfy deadline D within this period.

  • If water at low sensor: Task stops pump
  • If water at high sensor: Task starts pump

– Schedulability conditions: T + D < d

  • If the task finishes within the period (D = T ) :

2.T < d

T D d ¬ C C t

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5 Real-Time Scheduling

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6 Real-Time Scheduling

Avionics functions

  • Control and check airplane

– Navigation – Communication – Recording – Steering

  • Specific requirements for IMA

– auto check – maintenance checks

  • cost effective !!

– reliable

  • one hour < 10-9
  • last fault to maintenance > 200h
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7 Real-Time Scheduling

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8 Real-Time Scheduling

  • LRM: line replacable modules
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9 Real-Time Scheduling

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10 Real-Time Scheduling

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12 Real-Time Scheduling

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13 Real-Time Scheduling

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Video streaming over network into terminal

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Terminology Stream Composite stream Task Buffer User application Terminal application

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17 Real-Time Scheduling

enc. hw scaler enc. disk : non-scalable dmux audio dec. dec. sharp enh. main: scalabale DVD mixer mixer : non-scalable scaler digitizer: non-scalable digit audio rend read writer dec enc. scalable task task hierarchical task connection to HW IO buffer data transfer pip: scalable

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Application mode Mode parameters Stream modes Application graph

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Load changes in MPEG decoding

time load structural load running average temporal load

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20 Real-Time Scheduling

Control architecture in terminal

1a 1b 2a 2b 3a 3b 4a 4b 5a 5b 5c 6 Set up session Monitor / Alarm / Notify event Select and Set mode Monitor / Alarm / Notify event Set mode and quality level Monitor / Alarm / Notify event Set local parameters Monitor Alarm / Notify event Select and Set resource contract Monitor resource usage Monitor resource usage Resource usage Application Manager RCE control RCE operation Quality Manager Contract-based Resource Manager 1a 3a 2a 4a 1b 2b 5b 3b 5a 4b 5c Mode Manager

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Layered view of Integrated framework Network and terminal

Application Manager Mode Manager Terminal QM Subnet QM Terminal RM RCE Subnet RM NCE Terminal Subnet

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Terminal T1

Application A2

RCE A2 dmux audio dec. dec. sharp enh. mixer audio rend tuner

Subnet S1 Terminal T2

rend scaler digit RCE A3

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23 Real-Time Scheduling

Terminal T2 Subnet S1 Terminal T1

RCE A2 dmux audio dec. dec. sharp enh. mixer audio rend tuner router digit RCE A3,1 RCE A3, 1 router scaler

Stream transfer

NCE A3