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Reducing Peak Power with a Table-Driven Adaptive Processor Core

Reducing Peak Power with a Table-Driven Adaptive Processor Core. Vasileios Kontorinis (UCSD) Amirali Shayan (UCSD) Rakesh Kumar (UIUC) Dean Tullsen (UCSD). The Power Problem. $. $. $. $. Power related issues : Wall power costs Processor design constraints

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Reducing Peak Power with a Table-Driven Adaptive Processor Core

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  1. Reducing Peak Power with a Table-Driven Adaptive Processor Core VasileiosKontorinis (UCSD) AmiraliShayan (UCSD) Rakesh Kumar (UIUC) Dean Tullsen (UCSD)

  2. The Power Problem $ $ $ $ • Power related issues: • Wall power costs • Processor design constraints • Power delivery network • Thermals • Packaging • Reliability Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  3. The Power Problem $ $ $ $ • Power related issues: • Wall power costs • Processor design constraints • Power delivery network • Thermals • Packaging • Reliability Average Power Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  4. The Power Problem • Power related issues: • Wall power costs • Processor design constraints • Power delivery network • Thermals • Packaging • Reliability Peak Power Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  5. Theoretical Peak vs Execution Peak Power Time Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  6. Theoretical Peak vs Execution Peak Power Average Time Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  7. Theoretical Peak vs Execution Peak Execution Peak Power Average Time Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  8. Theoretical Peak vs Execution Peak Theoretical Peak Execution Peak Power Average Time Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  9. Our Approach • Motivation: • Most applications have few resource bottlenecks. • Ample opportunity to disable core components without hurting performance • Goal: • Partially disable core components to limit Peak Power • Method: • Each resource can be maximally configured • Not all resources maximized at the same time (centralized control mechanism). Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  10. Motivating Experiment: • We reduce 10 core resources Max config Min config Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  11. Motivating Experiment: • We reduce 10 core resources • We selectively maximize resources 10 params max 1 out of 10 parameters max Min config Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  12. Motivating Experiment: • We reduce 10 core resources • We selectively maximize resources 10 params max 2 out of 10 parameters max Min config Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  13. Motivating Experiment: • We reduce 10 core resources • We selectively maximize resources 10 params max 3 out of 10 parameters max Min config Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  14. Motivating Experiment: • We reduce 10 core resources • We selectively maximize resources • We can aggressively reduce core components and give up little performance Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  15. Outline • Introduction • Architecture • Results • Conclusions Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  16. Outline • Introduction • Architecture • Results • Conclusions Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  17. Baseline Architecture Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  18. Baseline Architecture with Average Power Management Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  19. Proposed Architecture with Peak Power Management Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  20. Proposed Architecture with Peak Power Management Holds possible core configurations Does bookkeeping and enforces configurations Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  21. Two Critical Issues • Which configurations to make available? (contents of Config ROM) • How to transition among the available configurations? (Adaptation manager policies) Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  22. Two Critical Issues • Which configurations to make available? (contents of Config ROM) • How to transition among the available configurations? (Adaptation manager policies) Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  23. Finding Appropriate Configurations Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  24. Finding Appropriate Configurations Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  25. Finding Appropriate Configurations • Consider all possible configurations 69% 71% Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  26. Finding Appropriate Configurations • Consider all possible configurations • Remove configs exceeding targeted peak power threshold 69% 71% Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  27. Finding Appropriate Configurations • Consider all possible configurations • Remove configs exceeding targeted peak power threshold 69% 68% Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  28. Finding Appropriate Configurations • Consider all possible configurations • Remove configs exceeding targeted peak power threshold • Remove redundant configs 69% 68% Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  29. Contents of the Config ROM • Manageable number of configurations • We find the best configuration faster Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  30. Implementation Overhead • Area: <1.25% increase (~0.5KB for Config ROM) • Peak Power: < 1.1% overhead • Average Power: negligible (infrequent epoch-based adaptation) • Power-gating delays of up to 650 cycles. • Verification Cost higher than non-adaptive core, less than fully-adaptive core Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  31. Outline • Introduction • Architecture • Results • Dynamic Adaptation vs Static Tuning • Realistic Adaptive Techniques • Voltage Variation and Decoupling Capacitance Benefits • Conclusions Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  32. Dynamic Adaptation vs Static Tuning 70% of core peak • Best Static Configuration: • iqs:32. fqs:32 ialu:2 falu:1 ldst:1 ics:16KB dcs:16KB ipr:64 fpr:64 rob:256 Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  33. Dynamic Adaptation vs Static Tuning 70% of core peak FP REGs needed INT ALUs needed Nothing needed • Best Static Configuration: • iqs:32. fqs:32 ialu:2 falu:1 ldst:1 ics:16KB dcs:16KB ipr:64 fpr:64 rob:256 Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  34. Two Critical Issues • Which configurations to make available? (contents of Config ROM) • How to transition among the available configurations? (Adaptation manager policies) Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  35. Realistic Adaptive Techniques Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  36. Realistic Adaptive Techniques Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  37. Realistic Adaptive Techniques Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  38. Realistic Adaptive Techniques Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  39. Realistic Adaptive Techniques e.g. INTVAD_SCORE_SAMPLE Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  40. Realistic Adaptive Techniques Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  41. Realistic Adaptive Techniques Most configs in Config ROMperform poorly Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  42. Realistic Adaptive Techniques SCORE marginally better than BEST_STATIC Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  43. Realistic Adaptive Techniques SAMPLING a big win! Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  44. Results Across Peak Power Budgetsvs Maximized Core • Reducing the configurations in Config ROM further improves performance • At 75% within 5% of maximized core • At 80% within 2.5% of maximized core Peak power constraint Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  45. So what have we gained? • Metrics • Power efficiency AP_ratio = • Decoupling Capacitance (% of total core area) • Voltage Variation (% of Vdd) Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  46. Power Efficiency Both average and peak power decrease Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  47. Power Efficiency AP_ratio: 56% 61% 63% 64% 67% Both average and peak power decrease AP_ratio improves as we constrain the peak power Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  48. Voltage variation and Decoupling Capacitance benefits Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  49. Voltage variation and Decoupling Capacitance benefits Micro'09: Kontorinis, Shayan, Kumar, Tullsen

  50. Voltage variation and Decoupling Capacitance benefits Micro'09: Kontorinis, Shayan, Kumar, Tullsen

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