1. Cache Replacement in Modern Processors
Prepared By:
Paul Kosinski and Bridget Johnston

2. Introduction
The replacement policy specifies which disk block should be removed when a new block must be entered into an already full cache, and should be chosen so as to ensure that blocks likely to be referenced in the near future are retained in the cache.

3. Common Cache Replacement Policies Used
Least Recently Used (LRU)
First In First Out (FIFO)
Last In First Out (LIFO)
Random (Rand)

4. Least Recently Used
Replaces the block in the cache which has not been used for the longest period of time
Advantage: simplicity
Drawback: does not consider file sizes & latency

5. First In First Out Last In First Out
Determines the oldest block rather than the least recently used.
Advantage: Easier to calculate
Last In First Out
Uses the newest block

6. Random Candidate blocks are randomly selected.
All disk blocks are accessed with equal probability
Used as a benchmark

7. Problem Statement
We will show the Cache Replacement Policy used by the Pentium III and Pentium IV processors and propose why each policy was used. We will use a simple matrix multiplication program and Vtune to determine our results.

8. Experimental Setup Matrix Multiplication program Vtune
Intel Pentium III machine
Intel Pentium IV machine

9. Experimental Process
Ran matrix multiplication program on Pentium III & IV with the following inputs as the dimensions of an n x n matrix:
128
256
512
1024
2048
4098
8192
160
320
640
1280
2560
5120
10240

10. Intel Pentium III results

11. Intel Pentium III results

12. Intel Pentium III results

13. Intel Pentium III results

14. Intel Pentium IV results

15. Intel Pentium IV results

16. Conclusion Results Don’t Mean Anything
Simple Hardware Required due to Timing Constraints
This Means Only Simple Algorithms Should be Used
LRU
FIFO