提要:
- 计算机八大思想
- 如何评价计算机的性能?——时间指标
内容:
Eight Great Ideas in Computer
- Design for Moore’s Law 摩尔定律
Integrated circuit resources double every 18–24 months.
IC上可容纳的晶体管数目,约每隔18个月便会增加一倍,性能也将提升一倍。 - Use Abstraction to Simplify Design 抽象化
high-level language program->compiler->assembly language program->assembler->binary machine language program
- Make the Common Case Fast 加速经常性事件
- Performance via Parallelism 并行
- Performance via Pipelining 流水线
- Performance via Prediction 预测
- Hierarchy of Memories 内存分层
- Dependability via Redundancy 利用冗余提高可靠性
** Performance**
CPI (Clock cycles per instruction): Average number of clock cycles per instruction for a program or program fragment.
CPU time = Instruction count * CPI * Clock cycle time
Amdahl’s Law: A rule stating that the performance enhancement possible with a given improvement is limited by the amount that the improved feature is used.
MIPS ( million instructions per second):A measurement of program execution speed based on the number of millions of instructions.
MIPS= Instruction count/ (Excecution time * 10^6) = Clock rate/ (CPI * 10^6)