Massachusetts Institute of Technology 6.375 Complex Digital Systems 2010 Spring Advanced Processor Design Group III Michael Eskowitz James Haupt Advisor: Muralidaran Vijayaraghavan Eskowitz, Haupt Page | 1 Table of Contents 1. Abstract ................................................................................................................................................. 3 2. Introdu ction .......................................................................................................................................... 4 3. Basic CPU Design ................................................................................................................................... 4 4. Advanced Processor Implementation ................................................................................................... 6 4.1. PCGen ............................................................................................................................................ 8 4.2. InstCounter ................................................................................................................................... 8 4.3. Branch Predictor ........................................................................................................................... 9 4.4. Decode ........................................................................................................................................ 13 4.5. Scoreboard .................................................................................................................................. 14 4.6. Exec ............................................................................................................................................. 15 4.7. BExec ........................................................................................................................................... 17 4.8. MExec .......................................................................................................................................... 18 4.9. Counter4 ..................................................................................................................................... 18 4.10. Writeback Stage ...................................................................................................................... 19 4.11. Multi‐Write Register File Implementa tion .............................................................................. 20 5. Results ................................................................................................................................................. 21 6. Conclusion ........................................................................................................................................... 23 7. Future Work ........................................................................................................................................ 24 7.1. Scheduling Algorithm Details ...................................................................................................... 24 7.2. Scheduling Algorithm Analysis .................................................................................................... 27 7.3. Application of Scheduling System for 3 Exec Modules ............................................................... 28 7.4. Hardware Details......................................................................................................................... 30 8. Bibliography ........................................................................................................................................ 32 Eskowitz, Haupt Page | 2 Table of Figures Figure 3‐1 Lab5 SMIPS Processor .................................................................................................................. 5 Figure 3‐2 Lab 5 Performance Metrics .......................................................................................................... 5 Figure 4‐1 Superscalar Processor Implementation ....................................................................................... 6 Figure 4‐2 Branch Instruction Life‐cycle ..................................................................................................... 10 Figure 4‐3 1‐bit Branch Predictor Accuracy ................................................................................................ 10 Figure 4‐4 1‐bit Branch Predictor State Transition Diagram ....................................................................... 11 Figure 4‐5 2‐bit Branch Predictor State Transition Diagram ....................................................................... 11 Figure 4‐6 2‐bit Branch Predictor Accuracy ................................................................................................ 12 Figure 4‐7 Tournament 2‐bit Branch Predictor State Transition Diagram .................................................. 12 Figure 4‐8 Tournament 2‐bit Branch Predictor Accuracy ........................................................................... 13 Figure 4‐9 Conceptual Representation of Decode Permutation Stage ....................................................... 13 Figure 4‐10 Intra‐Module Result Sharing Architecture ............................................................................... 14 Figure 5‐1 Summary of Benchmark IPCs ..................................................................................................... 21 Figure 5‐2 Comparison between issuing 2 or 1 instructions at a tim e ....................................................... 22 Figure 5‐3 Resource Utilization ................................................................................................................... 22 Figure 7‐1 Expanding Execution Network ................................................................................................... 25 Figure 7‐2 Probability of being able to schedule an instruction with two registers current in system ...... 27 Figure 7‐3 Potential Future Design Revision ............................................................................................... 30 Figure 7‐4 Long‐Term Architectural Goal .................................................................................................... 31 Eskowitz, Haupt Page | 3 1. Abstract In this project, we
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