Hints for Building Self Systems Vijay K. Garg The University of Texas at Austin Austin, TX 78712 ema

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Hints for Building Self- SystemsVijay K.
GargThe University of Texas at AustinAustin, TX
78712email garg_at_ece.utexas.edu
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Talk Outline

• Overview
• Hints for Self- Systems
• Specify Know your goals
• Observe Know your state
• Keep choices Know multiple ways
• Plan Know your strategy
• Control reconfigure, reset, reorganize, adapt
• Paradise

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Goal

• Identify research tasks for self- systems
• Identify current (mis)practices
• Publicize research at PDSLAB, UT Austin

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Specify Know your goals

• Biological Systems goals at multiple levels
• Survival, happiness, money, job
• Computer Systems are not aware of their goals
• At best, we have specs of the programs
• Need
• Specs at multiple levels
• Using Specs for Runtime Verification
• Adapting to the environment

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Observe Know your state

• Self-awareness is the state consistent with
  goals?
• Monitoring for system properties
• Stable Properties e.g. Chandy,Lamport 85
• Unstable Properties
• Single State based e.g. Linear Predicates Chase,
  Garg 95, Relational Predicates Tomlinson, Garg
  96
• Temporal Logic based e.g. Regular CTL Sen, Garg
  04
• Need
• Integration with runtime environments

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Choices Know multiple ways

• Determinism considered dangerous
• Nondeterminism allows the system to deal with
• Faults
• Uncertainty
• Changing environment
• Need
• Nondeterministic choice in general prog.
  Languages (e.g. Dijkstras Guarded Command
  Language)
• Support for selective communication (e.g. CSP)
• Support for family of modules

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Plan Know your strategy

• Know your state space
• Exploit what computers are good at
• View program as two parts
• Finite state part computer analyzable
• Infinite part trust humans
• Lookahead Execution
• Computation slicing Garg, Mittal 2001
• Need
• Support for systems with lookahead
• Support for on-the-fly model checking

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Control Controlled Execution

• Use nondeterminism to your advantage
• Try different order of message processing
• Impose additional synchronization Tarafdar, Garg
  04
• Supervisory Control of Discrete Event Systems
  Ramadge and Wonham 89, Kumar and Garg 95
• Tunable parameters (adaptive control)
• Need
• execution environments with control
• Programming languages that support feedback

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Paradise Project

• Key Abstraction Global Properties
• Model Checking and Verification Check global
  properties against model of the program (Promela)
• Simulation and Debugging Global breakpoints,
  Trace analysis
• Fault-Tolerance Monitoring for global
  properties, Controlled Re-execution

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Paradise Environment
Control
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Paradise Tools

• Trace Cover SPIN (Model Checker) alleviating
  state explosion
• Visual Dashboard
• Partial Order Trace Analysis (POTA) slicing
• Paradise Library tracking dependency, global
  snapshot, global properties
• Paradise Execution Engine control

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Conclusions

• Current execution engines are too primitive to
  build self- systems
• Need more knowledge
• Goals, multiple choices, current state
• Research at PDSLAB
• www.ece.utexas.edu/garg/pubs.html