EEL5708/Bölöni Lec 1.1 8/27/03 August 25, 2004 Lotzi Bölöni Fall 2004 EEL 5708 High Performance...

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August 25, 2004Lotzi Bölöni

Fall 2004

EEL 5708High Performance Computer Architecture

Lecture 1

Introduction

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Acknowledgements

• All the lecture slides were adopted from the slides of David Patterson (1998, 2001) and David E. Culler (2001), Copyright 1998-2002, University of California Berkeley

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Case 1: VIA KT266 chipset for the Athlon processors

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Take 1: April 4, 2001

• Tom’s Hardware ( www.tomshardware.com). Web site for hardware entusiasts.

• Review of the VIA Apollo KT266 chipset. • http://www17.tomshardware.com/mainboard/

01q2/010409/kt266-10.html• The website’s conclusion: KT266 is still way too slow to challenge or even replace AMD's 760 chipset.

As a conclusion, I could maybe say the typical words always used in early reviews "let's hope VIA will finally improve KT266". However, I have my doubts if this will happen any time soon. My advice to you is to either forget about DDR altogether for the time being, or to go for Athlon plus AMD760 and NOTHING ELSE.

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Take 2: One week later…

• Article title: “VIA Apollo KT266 revisited: Much Ado About Nothing” (http://www17.tomshardware.com/mainboard/01q2/010416/index.html)

• Another website (www.anandtech.com) obtains different results.

• An additional resistor (!) mounted on the motherboard and a different BIOS.

• Tom’s Hardware concludes that there are indeed improvements, but they are not significant enough to change the conclusion.

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Take 3: Five months later (September 2001)

• VIA KT266A is launched• Tom’s Hardware: “’A’ stands for vastly improved

performance” (http://www17.tomshardware.com/mainboard/01q3/010902/index.html)

• Changes: “improvements” to the memory controller.

• Processor frequency, bus frequency, etc. stay the same. Pin-by-pin compatible with the predecessors!

• Conclusion: “The performance of Apollo KT266A is nothing short of impressive.”

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Synthetic benchmarks:

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Real world benchmarks

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Some conclusions• “Architecture” matters.• Real world benchmarks less improvement

than synthetic ones: Amdahl’s Law• Which benchmark do I care about? (this time

at least, they were consistent…)• …

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Case 2: Video compression performance in Intel Pentium 4 vs.

AMD Athlon

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Take 1 (11/20/00): First impressions

• Intel Pentium 4 is launched. • The initial measurements show that it

greatly overperforms the AMD Athlon for MPEG 4 video compression.

• http://www6.tomshardware.com/cpu/00q4/001120/index.html

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Take 1 (11/20/00): First impressions (cont’d)

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Take 2: New results force new conclusions

• Concerns are raised about the fact that the measurement was done with a low quality setting (MMX arithmetics)

• Repeating the measurements with floating point arithmetics, the relative performance was reversed.

• http://www6.tomshardware.com/cpu/00q4/001122/index.html

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Take 2 : New results force new conclusions (cont’d)

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Take 3: Intel engineers create an optimized version of the

software

• As a response, Intel engineers created a modified version of the software:

-recompiled it with higher optimizations. -rewritten parts of the code to use the new instruction

set extensions (SSE2)• The higher optimizations benefited both Intel

and AMD processors (but Intel more)• The SSE2 options reversed the performance

ranking again. • OBS: AMD engineers created an AMD

optimized version, too, with significant improvements, but this did not change the rankings.

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Take 3: Intel engineers create an optimized version of the

software

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Take 3 (cont’d)

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Case 2: Conclusions

• Real world benchmark, huge differences– Why?

• Software solution to a hardware problem?– Optimizing for the architecture– So, what if it is not open source?– Software development cycles…

• Picking the right architecture + understanding the architecture we have

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Coping with EEL 5708• Students with too varied background?

– This class assumes that you know» basic computer architecture» assembly language programming

• Review: “Computer Organization and Design (COD)2/e”

– Chapters 1 to 8 of COD if never took prerequisite– If took a class, be sure COD Chapters 2, 6, 7 are

familiar• We will do a fast review of Pipelining,

Performance, Caches, and Virtual Memory

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EEL 5708 Administrivia• All lectures will be available via WWW page:

http://www.cs.ucf.edu/~lboloni/Teaching/EEL5708_2004/index.html

• Text: Computer Architecture: A Quantitative Approach, Third edition

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Grading• 20% Homeworks• 30% Midterm• 50% Final Exam