Sogang University Advanced Computing System Chap 2. Processor Technology Hyuk-Jun Lee, PhD Dept. of Computer Science and Engineering Sogang University Seoul, Korea

Sogang University Contents Single cycle processr Pipelined processor Deeply pipelined processor Wide or superscalar processor Out-of-order execution processor

Sogang University Why do we study different processor types?  Different processor architectures provide different performance and power consumption for given applications.  High performance processor with high clock frequency consumes more power than low performance processor for the same performance. Performance and power of big and little processor for web page loading [Zhu et al, HPCA ‘13]

Sogang University 4 Picture of processor  Area is translated into cost and performance  There is a trade-off between cost and performance

Sogang University 5 Single cycle processor design

Sogang University Pipelining Analogy Pipelined laundry: overlapping execution – Parallelism improves performance Four loads: Speedup = 8/3.5 = 2.3 Non-stop: Speedup = 2n/0.5n ≈ 4 = number of stages

Sogang University MIPS Pipeline Five stages, one step per stage 1.IF: Instruction fetch from memory 2.ID: Instruction decode & register read 3.EX: Execute operation or calculate address 4.MEM: Access memory operand 5.WB: Write result back to register

Sogang University 8 Pipelined processor design

Sogang University 9 Processor performance

Sogang University 10 5 stage pipelined processors

Sogang University 11 Improving the 5-stage pipeline performance

Sogang University 12 Deeper pipelines

Sogang University 13 Deeper pipeline review

Sogang University 14 Wide or superscalar pipelines

Sogang University 15 Superscalar pipelines review

Sogang University 16 Diversified pipelines

Sogang University 17 Modern superscalar out-of-order processor

Sogang University 18 Memory Hierarchy in Modern Processors

Sogang University 19 Challenges for Superscalar Processors