An Analysis of SIMD Instructions in the Pentium III Microprocessor

By Alexander J. Aved

<aaved@cs.bsu.edu>

05 DEC 2000

CS689

Ball State University

Muncie, Indiana

TOC

•Problem Description•Problem Statement•Research Objectives•Literature Review•Importance•Research Design•Data Analysis•Schedule•Facilities•Deliverables•Summary

Problem Description

The Intel Pentium III microprocessor has 70 new instructions, many of which are SIMD instructions, among other enhancements over the Pentium II.

The cost of producing a new microprocessor is very high, and if the benefits of using the latest processor are marginal, Intel will need a way to get people to buy it.

Problem Statement

In my research I will determine if the Pentium III’s SIMD instructions offer a performance increase that is noticeable to the typical home computer user, or if the functionality provided by the SIMD instructions are of little benefit to the typical home computer user.

Problem Statement(Cont)

Sub-problems

•What software is included in a home computer?

•Which software benefits from SIMD instructions?

Problem Statement(Cont)

Delimitations

•Limit software to pre-installed software from computer vender

•I will choose 15 computers to analyze (10 desktops and 5 laptops), $2,000-$2,500 price range

•All will be configured with Windows 98 Second Edition

Research Objectives

The objective of my research is to determine if the SIMD instructions in the Pentium III microprocessor actually facilitate an increase in performance that is relevant to the average home computer user, or are the performance gains provided by the SIMD instructions insubstantial.

Literature Review

•Overview of Intel 32-bit ISA

•Overview of SIMD instructions in Pentium III

•Some applications of SIMD instructions

•Some “non” applications of SIMD instructions

•Current research trends in this area

Literature Review(Cont)

32-bit Dynamic Execution Architecture

•Out-of-order execution

•Superscalar

•Pipelined

•Branch Prediction

Literature Review(Cont)

SIMD Instructions in the Pentium III

•MMX – Multi-Media eXtensions (57 Instructions, 1997)

•Mapped 64-bit MMX registers onto 80-bit floating-point registers

•Streaming SIMD Extensions (SSE)

•8 new 128-bit registers added

•I use the term SIMD to include SSE and MMX instructions

Literature Review(Cont)

Applications of SIMD

•DSP

•Fast Fourier- and Inverse Discrete Cosine transformations (used in MPEG and JPEG, respectively)

•Many more (fluid dynamics, weather modeling, VLSI circuit routing, etc.)

Literature Review(Cont)

Non-Applications/problems with SIMD Instructions

•A high degree of data parallelism is needed

•CPU-intensive applications

•Integer SIMD/floating point problem

•OS support needed (context switch)

Literature Review(Cont)

Current trends in this area

Current trends may be grouped into three major categories

1) Make SIMD machines behave like MIMD machines

2) Scientific applications of SIMD (fluid dynamics, computer vision, etc.)

3) Investigation of SIMD instructions in non-SIMD microprocessors with respect DSP and image compression

My research is a totally new approach

Importance

The goal of this research is to show that the SIMD instructions in the Pentium III, by themselves, do not significantly enhance the computing experience of home computer users.

With the results of this research someone in the market for a home computer can make a more educated decision as to whether or not they need a computer with a microprocessor that includes SSE in its ISA.

Research Design

The software will be categorized by type:

•Word Processing/Page Layout (PageMaker)

•Data Entry (MS Money)

•Data Lookup (an encyclopedia)

•Spreadsheet (Excel)

•Web Browsers (Netscape)

•Educational/Tutorial

•Media Players (Real Audio player)

•Other/Miscelaneous

Research Design(Cont)

The software will be subcategorized based upon inherent data parallelism, dependence on connection speed to other computers, or if the CPU is a bottleneck for the performance of the software.

Of the software that has data that exhibits significant parallelism to warrant the use of SIMD instructions, the VTune Performance Analyzer will be used to determine if the product actually uses any SIMD instructions.

TOC

•Problem Description•Problem Statement•Research Objectives•Literature Review•Importance•Research Design•Data Analysis•Schedule•Facilities•Deliverables•Summary

Data Analysis

This research is a qualitative analysis of the benefits of the SIMD instructions to home computer users. My data analysis section will consist of a table showing which software products have data that exhibit significant parallelism to benefit from SIMD instructions, the software that currently uses SIMD instructions and the software that would has no need for SIMD instructions due to the asynchronous nature of its data.

Schedule

Planned project duration: 11 months

Month 1: obtain computer equipment and software

Months 2 through 9: perform analysis as previously described

Month 10: create final report

Month 11: present findings

Facilities

•An Internet connection (56.6K would be adequate)

•VTune Version 4.0 (from Intel)

•Fifteen computers (10 desktop, 5 laptop) (including software)

Deliverables

Research Report

Summary

I plan to show that the Intel Pentium III microprocessor incorporates SIMD instructions that are very useful for scientific applications, but are of limited use in the home computing environment.

References available at: http://www.cs.bsu.edu/~aaved/Research_Proposal.doc

Presentation available at: http://www.cs.bsu.edu/~aaved/Presentation.ppt

Questions?Questions?