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Power Modeling and Power Management Framework

Power Modeling and Power Management Framework. Dexin Li December 2002. Outline. Background Power management architecture Component-level power modeling System-level power simulation Energy optimization Preliminary results. Background .

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Power Modeling and Power Management Framework

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  1. Power Modeling and Power Management Framework Dexin Li December 2002

  2. Outline • Background • Power management architecture • Component-level power modeling • System-level power simulation • Energy optimization • Preliminary results

  3. Background • Challenges on power management in complex embedded systems • Interaction and cooperation among multiple components • Existence of inter-component dependencies • Complicated local mode transitions for a global mode change • High cost for a global mode change • Scope of the work • Purpose a software architecture dealing with power management complexity • Model components and component modes with dependency • Generate feasible sequence of mode transitions • Optimize the energy for the cost of mode changes

  4. Power Management Architecture • Separation of policy-maker and component details • Modular, retargetable, • Lessen the burden of policy-maker • Hierarchical component model • Capable of handling complex systems • Modeling of inter-component dependency • Enabling complicated mode transition optimization • Online or offline power simulation • Helpful in obtaining feasible mode transitions and optimizing system energy

  5. Execution Model of Power Management We assume this model in the rest of the presentation. Application Power manager Middle-ware Operating System Hardware device

  6. Top-Level Power Manager System spec Power Manager Power simulator Requirements Power/battery status app External policy Message to app. App. status Task constraint Message to os os OS/MW status Control command Component library Interdependency hw Device status

  7. Decoupled Power Management Architecture Diagram

  8. Policy Handler • Responsibilities • monitor system status • Make system-level power management policies • Send mode change commands • System interaction • Accept service requests from applications • Accept system requirement or environment input from middle-ware • Obtain system status from middle-ware or OS • Send mode change commands to Component Manager

  9. Component Manager • Command Interpreter • Receive system command from policy handler • Translate system command into local command • Core algorithms • Generate sequence of mode transitions • Optimize it for energy reduction • Send results to device drivers • Feed results to simulation engine

  10. Policy Handler Device driver Component Manager Diagram Component Manager System status Command Interpreter MTG 1 Mode Dependency Model MTG 2 Core Algorithms MTG n Device status

  11. tx off sb off off on on rx f1: fsm_lb f3: temp_lb tx off sb f4: temp_hb rx f2: fsm_hb Component Modeling Example: Power Amplifier System status F1.sb->f2.off F1.tx->f2.off F1.rx->f2.off F2.sb->f1.off F2.tx->f1.off F2.rx->f1.off F1.sb->f3.on F1.tx->f3.on F1.rx->f3.on F2.sb->f4.on F2.tx->f4.on F2.rx->f4.on Command Interpreter All-pair-shortest-path Algo. (Floyd-Warshall) Device status Dependency model Component manager for PA

  12. tx off sb off on rx f1: fsm_lb tx off sb f4: temp_hb rx f2: fsm_hb Component Manager Example: Power Amplifier Current state: low band transmit System command: change to high band receive State transition sequence: f1.tx -> f1.sb -> f1.off f2.off -> f2.sb -> f2.rx f4.off -> f4.on Energy: 3.88J Optimized for energy reduction: f1.tx -> f1.sb -> f1.off f4.off -> f4.on f2.off -> f2.sb -> f2.rx Energy: 1.88J

  13. System-level Mode Simulation • Responsibility • Receive sequence of mode transitions • Simulate mode transitions • Parallelize possible mode transitions • Obtain time and energy information • Send the information back to Policy Handler • Requirement • Detailed timing information for synchronization • Hierarchical component management • Parallelism among different components • Interface to other power management units

  14. Simulation Engine Diagram

  15. Energy Optimization • Objective • Optimize energy consumption for mode changes • Techniques • Shortest-path algorithm to optimize for one mode change on one component • Topological sorting to power up high power component as late as possible • Mode simulation to parallelize certain mode changes

  16. Modeling a JTRS Channel • Complex system composition • 13 power manageable components • Multiple power modes on each component • Complicated inter-component dependencies • derived from system specification and application requirements • Complicated mode changes • Involve more than one component for a mode change • Take a period of time comparable to the service time

  17. Experimental Results • Test cases: • Case 1: all power-up • Case 2: two modes: on and off • Case 3: 5 system modes without our model • Case 4: 5 system modes with our modes • Results: • Saves 50%-80% energy when service time is comparable to overhead time • Saves 20%+ energy when service time is 1000x larger than overhead time

  18. Conclusion • A new software architecture supporting efficient power management in complex systems • Component power model enabling power management in complex systems with dependency • Multiple optimization techniques reducing energy cost for global mode changes • System-level simulation providing optimized component-level details to global policy-maker

  19. End Slide

  20. Application Middle-ware Power manager Operating System Hardware device Execution Model of the Power Manager Not clear what execution model is best/feasible/practical…

  21. Device Broker System power manager System status Command receiver/ interpreter MTG 1 Mode Dependency Model MTG 2 Broker core MTG n Device status Device driver

  22. tx off stb rx Mode Transition Graph

  23. Application Power manager Middle-ware Operating System Hardware device Execution Model of the Power Manager Not clear what execution model is best/feasible/practical...

  24. Execution Model of the Power Manager Not clear what execution model is best/feasible/practical… Application Middle-ware Operating System Power manager Hardware device

  25. Execution Model of the Power Manager Not clear what execution model is best/feasible/practical… Application Power manager Middle-ware Operating System Hardware device

  26. Device model Device model Device status Device status Device driver Device driver Device broker I Device broker II More Detailed Power Manager Composition Simulation Engine Power Manager (core) Component library Sys. specification App. Requirements App/task Constraints Power management policy Sys/app status

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