11

Reading Assignment and Discussion Topics
Computer Science 471

for class on Thursday Oct. 19, 2000

Please read Chapter 2 of the Patterson & Hennessy text, and be prepared to discuss the following issue:

The expression of execution time as the product of number of instructions, average CPI, and cycle time is fundamental to the correct analysis and understanding of uniprocessor performance. It would be great if the various contributors to performance (like architectural features, technology, and so on) only affected one term in this product. But usually they affect two terms, sometimes increasing or decreasing both, but often making one go up and another down. Trade-offs result. What things affect what terms in which way? Consider:

• instruction-set architecture (for example, complex or powerful instructions versus simple ones, or MIPS' register scheme versus SPARC's);
• technology (gate speed and chip density);
• code optimization by the compilers;
• hardware organization (for example, chapter 5's single-cycle versus multi-cycle MIPS designs);

• choice of algorithm.