Understanding Software Dynamics

Chapter 3

Measuring Memory

In the previous chapter, we explored measuring CPU performance, the first of the four fundamental hardware resources.

The second fundamental resource to measure is memory access latency—how long do real computer reads and writes take, for each level of the memory hierarchy? A simple measurement of the latency of a single data load is even more subtle than the measurement of arithmetic instructions. The goal in this chapter is to measure the size and organization of the typical four-level memory subsystem in modern machines.

3.1 Memory Timing

This is the most complex topic in Part I. We will examine several design layers, each with its own concepts and constraints. Because main memory is so much slower than CPUs, modern ...