1 Fundamentals of Computer Design (cont.)
The main factors affecting costs: time (learning curve), yield, extent of commercialization (competition, etc.). Experience formula: COST OF DIE = F (DIE Area ^ 4). (Andy: Data is more early, take alpha = 3.0, third editions Alpha = 4.0, as if the 2001 data) Only the execution time of the real program is a measurement indicator for machine performance and reliable. Pay attention to the difference between the passage time and the CPU time during measurement, and generally measurement is always carried out on the operating system. (ANDY: You can refer to the classification of the evaluation procedure for time measurement in "in-depth understanding of computer systems":
REAL Program Kernels Toy Benchmarks Synthetic Benchmarks Guidelines: Reproducibility Performance Evaluation and Compare Aspects:
The program selection experimental environmental measurement indicator (how to define a quick slow) Data Table Method After the execution time, the geometric mean should be used to use geometric mean, which will not be subject to different impacts by the reference. Problem of geometric mean: Reflecting the evaluation score calculated by the geometric mean calculation of the execution time, can be improved by improving the performance of the most optimized program. As the following two optimizations are the same, the score is the same:
Procedure 1, execution time is reduced from 2 seconds to 1 second;
Program 2, execution time is reduced from 10,000 seconds to 5000 seconds.
Ideally: Measure the actual workload, assign the weights to each program reflect the weight of the actual execution frequency.
If you can't get the weight, the normalization is made, and all the programs are tongue;
If you want to make specifications, it is best to take a total of weights and then regulate.
(Andy: It is also the weight, defeat the weight! There is no appropriate weight allocation, which will result in the result of the wrong!)
Guidelines for computer design quantization methods: make the common case fast / amdahl's law.
Speedup = Original Execution Time / Enhanced Execution Time
Speedup = 1 / (1 - Enhanced Fraction Enhanced Fraction / Enhanced Speedup <1 / (1 - Enhanced Fraction)
CPU Time = IC * CPI * Cycle Time
Evaluate the factors of the CPU time:
Clock Time: It is difficult to estimate, especially in the design. Generally, the target frequency is set, and the effect of evaluating critical paths is evaluated. Need experience.
IC: The compiler is critical. It is important to develop compilers as soon as possible for new ISA. Getting data:
Simulator: Speed is a problem. Factors affecting speeds: the structure of the program quality, the target, and the host machine (ANDY:
Why? ).
Execution-based Monitoring: Typical Instrument, execution time is 1.1-1.2 times. (Andy: I didn't pay attention before,
Learn about it)
CPI: and Organization. CPI = PIPELINE CPI Memory System CPI. Partiality: about 10% of the instructions account for 90% of the total execution time.
