1. Chia-Yen Hsieh Laboratory for Reliable Computing Microarchitecture-Level Power Management Iyer, A. Marculescu, D., Member, IEEE IEEE Transaction on VLSI System, June 2002

2. Laboratory for Reliable Computing Chia-Yen Hsieh 2 Outline  Introduction  Hotspot detection  Energy optimal configuration  Implement  Result  Conclusion

3. Laboratory for Reliable Computing Chia-Yen Hsieh 3 Low Power Issue  Market for mobile and embedded systems is expanding at a rapid rate, battery life is important  System-level power management  Memory and cache power optimization  Low-power sleep mode  Dynamic supply voltage variation  Microarchitecture-level  Trade-off between energy and performance  Execution application program for low power using profiling

4. Laboratory for Reliable Computing Chia-Yen Hsieh 4 Execution Profile  Wide variation in resource usage from one section of an application’s code to another  Execution profile of epic benchmark

5. Laboratory for Reliable Computing Chia-Yen Hsieh 5 Energy Variation  The quantity and organization of the processor’s resources will affect the overall execution profile and the energy consumption  Energy variation of lisp benchmark

6. Laboratory for Reliable Computing Chia-Yen Hsieh 6 Motivation  Low-end configuration consume higher power  Higher CPI  High-end configuration consume higher power  Resource usage  Power of unused module  Identify the right configuration for each code region in terms of various processor resources

7. Laboratory for Reliable Computing Chia-Yen Hsieh 7 Basic Block and Hotspot  Basic block  branch  Hotspots  collection of basic blocks frequently execution

8. Laboratory for Reliable Computing Chia-Yen Hsieh 8 Hotspot Detection Hardware

9. Laboratory for Reliable Computing Chia-Yen Hsieh 9 Execution Time Spent in Hotspots  Optimal configuration for that hotspots

10. Laboratory for Reliable Computing Chia-Yen Hsieh 10 Energy-Optimal Configuration  Configuration : combination of several processor parameters under control  Optimum configuration : least energy dissipation per committed instruction  Determine approximate energy dissipation

11. Laboratory for Reliable Computing Chia-Yen Hsieh 11 Energy-Optimal Configuration  Run 14 benchmarks  Energy consumption > 70%  Relative pre-access energy consumption on hottest parts of the simplescalar processor model

12. Laboratory for Reliable Computing Chia-Yen Hsieh 12 Power-Profiling Hardware

13. Laboratory for Reliable Computing Chia-Yen Hsieh 13 Optimal the Configuration  Hotspots is detected  Estimate power dissipation for all possible configurations  Optimal configuration of the processor for current hotspot is determined  Processor is switched to optimal configuration for the whole duration of the hotspots

14. Laboratory for Reliable Computing Chia-Yen Hsieh 14 Experiments  Baseline configuration used

15. Laboratory for Reliable Computing Chia-Yen Hsieh 15 Processor Model with Profiling Hardware

16. Laboratory for Reliable Computing Chia-Yen Hsieh 16 Power Variation

17. Laboratory for Reliable Computing Chia-Yen Hsieh 17 Energy Variation

18. Laboratory for Reliable Computing Chia-Yen Hsieh 18 Instruction Window Energy Variation

19. Laboratory for Reliable Computing Chia-Yen Hsieh 19 Performance Variation

20. Laboratory for Reliable Computing Chia-Yen Hsieh 20 Result  Saving obtained using run-time resource scaling

21. Laboratory for Reliable Computing Chia-Yen Hsieh 21 Conclusion  Major execution time of most applications is spent inside hotspots  Detect hotspots  Optimize the processor’s energy consumption inside hotspots  Increase in energy-efficient of the machine  Saving more power and energy with less performance penalty