Cache Memory

11/9/98


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Table of Contents

Cache Memory

Administrivia

Outline of Today’s Lecture

The Big Picture: Where are We Now?

The Motivation for Caches

Levels of the Memory Hierarchy

The Principle of Locality

Memory Hierarchy: Principles of Operation

Memory Hierarchy: Terminology

Direct Mapped Cache

The Simplest Cache: Direct Mapped Cache

Direct Mapped Cache (Cont.)

Example: 1-KB Cache with 32B blocks:

Example: 1KB Direct Mapped Cache with 32B Blocks

Example: 1K Direct Mapped Cache

Example: 1K Direct Mapped Cache

Example: 1K Direct Mapped Cache

Example: 1K Direct Mapped Cache

Example: 1K Direct Mapped Cache

Block Size Tradeoff

A N-way Set Associative Cache

Advantages of Set associative cache

Disadvantage of Set Associative Cache

And yet Another Extreme Example: Fully Associative cache

Sources of Cache Misses

Sources of Cache Misses

The Need to Make a Decision!

Cache Block Replacement Policy

Cache Write Policy: Write Through versus Write Back

Write Buffer for Write Through

Write Buffer Saturation

Write Allocate versus Not Allocate

Four Questions for Memory Hierarchy Designers

What is a Sub-block?

Email: alvy@cs.duke.edu

Home Page: http://www.cs.duke.edu/~alvy