11

Reading and Writing Assignments, Discussion Topics
COS/ELE 375

for class on Monday Oct. 25, 2010

Please read Section 1.4 of the text, and then skim the remaining portions of chapter 1 that touch on performance, notably Figure 1.16, the discussion of the SPEC benchmark idea in Section 1.7, and Section 1.8.

In honor of Midterm Week, there will be no written assignment for today's class.

But nevertheless please be prepared to discuss the following in class:

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);
• technology (gate speed and chip density);
• code optimization by compilers;
• hardware organization (for example, chapter 4's single-cycle MIPS design versus the multi-cycle alternative of last week);

• choice of algorithm.