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Recent Advances in Microprocessor Design

Christian Manfred Wimmer, S0501100,

Student Computing & IT, Year3

EMT64 and started to offer products for workstations and

Abstract

--This paper will give an overview of the recent

small servers. [2]

advances in microprocessor design. It will cover 64bit processors,

Due to the lack of applications and operating systems that

specially designed mobile CPUs, and multi-core technologies

support 64bit, the technology hasn′t quite kicked off yet.

along with Hyper-Threading Technology. Finally, as glance on

Luckily AMD64/EMT64 is an extension to the 32bit software

things to come, hardware support for Virtualization will be
covered.

model and therefore 32bit software is running on this CPU

without major speed losses. Probably the biggest problem of

Index Terms

--Microprocessors, Virtual computers, Parallel

the 64bit technology is the driver support. The 64bit operating

processing

systems require new 64bit drivers and as drivers for many

operating systems, including the famous Windows, are closed

source. Unless there is a generic driver old hardware may

I. INTRODUCTION

become redundant and it might take a while until a wide

LOT has happened since the first transistor based CPUs

variety of 64bit drivers will be available.

A where sold in the late 70s. This paper will give an In the Wintel world the upcoming Windows Vista will play an

overview of the recent advances in microprocessor design.

important part in the future of 64bit CPUs as it will be

available in 64bit and will come with a many 64bit drivers.

The 64bit technology turns out to be far less effective as the

II. 64BIT PROCESSORS AND THE MASS-MARKET

marketing departments want us to believe. Unless the

In 2003 a new revolution started, that is, when you listen to the

applications you run use a ton of memory, and not a lot of

marketing department of AMD and alike. In fact 2003 marks

them do, 64bit is more or less useless at the moment for the

the introduction of 64Bit CPUs to the mass market. 64Bit

average user. However chances are high that a 64bit CPU will

wasn′t that new as it sounded because MIPS, Sparc and Alpha

be in the next PC you buy, and as it runs 32bit software

CPUs where already available for a few years and with the

without speed losses there is no harm done.

Playstation 2 this type of CPU already found its way into our

living rooms.

III. GOING MOBILE

So what is all the fuss about, you might ask? The answer is

A. Need for mobile CPUs

quite simple ­ it′s all about RAM and the addresses needed to

organize it. A normal PC can handle up to 4 GB of RAM

The power consumption of Desktop CPUs is rising

without a problem but a look at the inside shows that Windows

constantly. The heat that is produced is also a problem and the

XP for example takes around half of that memory for itself,

cooling systems needed to keep the CPUs from melting also

leaving only 2 GB for the applications. In case you ever

drain a lot of power. Electric energy however is the one thing

worked with large databases or love to render 3D pictures you

that is always short when it comes to mobile computing. No

probably know that this kind of applications can never have

one is willing to carry his Laptop or PDA around with a car

enough memory and 2 GB virtual address space suddenly

battery. Therefore power saving is a major issue in mobile

seems to be relatively tiny. [1]

computing. Mobile CPUs can be divided into two classes. [3]

Normally Intel is the company who pushes new innovations

forward, but in this case AMD was the one to introduce 64Bit

B. Mobile variants of Desktop CPUs

to the consumer market. In the middle of 2004 Intel realized, it

Mobile variants usually work just like their Desktop siblings.

has to do something in order to keep up with the success of

These CPUs have been carefully selected by the manufacturers

AMD and it was decided that the technology AMD64 will be

for low power consumption. One a single silicon wafer

used in new Intel CPUs. A lincence trade agreement allowed

hundreds of CPU cores are created and some of those are able

Intel to do this without paying royalties to AMD. Intel called it

to reach high clock speeds at relatively low supply voltage.

To reduce the requirement for power even further mobile

CPUs also get taught a few tricks, however special

Manuscript handed in March 19, 2006.

motherboards (like in Laptops) are needed for this.

Christian Manfred Wimmer is a student at the North East Wales Institute

Normal office software like MS Office usually doesn′t use a

of High Education, dept. School of Computing & Communications

Technolody and is aiming for a BSc (hons) Computing & Information

lot of CPU power and therefore the CPU is idling most of the

Technology degree

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time and this circumstance is used for power saving. Basically

can be fixed (Pentium bug), this works pretty much like a

the CPU shuts down all non essential resources and consumes

BIOS update.

less power this way. Nowadays this kind of CPUs also sleeps

LongRun

power management is basically controlled by the

in between keystrokes of even the fastest writer.

Code Morphing, allows the processor to adjust its clock

This kind of CPUs is often easily distinguished from normal

frequency and voltage on the fly. Because power varies

desktop CPUs by a little `mobile′ in the name like Intel′s

linearly with clock speed and by the square of the voltage,

Mobile Pentium.

adjusting both can produce

cubic

reductions in power

consumption whereas conventional CPUs can adjust power

C. Specially designed power saving CPUs

only linearly. A conventional CPU, throttling back the

Special CPU architectures promise even more energy

processor speed by 10% cuts power by 10%, whereas under

efficiency. The following architectures have been designed

the same conditions, LongRun power management can reduce

with the requirements for mobile computing in mind.

power by almost 30%. Although this technology help to save a

lot of power Transmeta hasn′t had very much success with it in

1) Intel Centrino

the past few years.

The most well known brand in this sector is probably Intel′s

Centrino Architecture. The designers of this architecture took

3) ARM ­ small and powerful

a close look at the Pentium architecture and tweaked it for

ARM, whose Headquarter is based in Cambridge, United

power saving as much as they could, without sacrificing too

Kingdom, is the industry′s leading provider of 32-bit

much performance in the process [4].

embedded RISC microprocessors with almost 75% of the

The Pentium-M only uses about 6 Watt in battery-operation

market (2002)[7]. ARM is a "fabless" company ­ they only

and under full-load while it′s Desktop sibling, the Pentium IV,

sell , "intellectual property` such as Core designs. Licensees

uses above 24 Watt. A Pentium-M clocked at 1.5 GHZ should

include big names like Intel, IBM, Motorola, Samsung...

have the same performance as a 2 GHZ Pentium 4, not bad

pretty much everyone in the semiconductor market! [8]

when you keep in mind that it uses less than a quarter of the

Jazelle

is a technology that allows ARM CPUs that implement

power. [5]

it, to run Java bytecode natively. This technology is often used

by mobile phone manufacturers to speed up execution of Java

2) Transmeta

games and apps, which is probably what drove development of

A different approach is used by the company Transmeta with

the technology.

their Cruseo, or the newer version Efficeon, design. They are

Thumb

allows the 32bit ARM RISC processors to partly

using a technology known as `

Code Morphing

′[6].

operate in 16bit mode to, simplified, save a little Memory.

Transmeta CPUs can be seen as somewhat incomplete, the

This has been introduced at a later stage of the development on

Code morphing engine emulates all the missing functions. This

demand by the manufacturers. This is out of the ordinary as

special software is loaded right after the start of the system

ARM has therefore gone 32bit -> 16bbt, and not the other way

round like Desktop CPUs.

Our modern life demands flexibility and mobility. Notebooks

are replacing normal Desktop PCs more and more and the

recent boom in mobile MP3 players like the iPod has created

an enormous market for mobile CPUs. This trend will surely

not stop overnight and therefore specially designed CPUs for

this market have a bright future, along with the manufacturers

that manage to stay on top of the technology curve.

IV. MULTI CORE AND PARALLEL PROGRAMMING

Everyone wants more CPU performance, but not necessarily

pay more for it. However the cost for speeding up CPUs is

increasing exponentially. In the last couple of years it has

turned out that with today′s production techniques in CPU fabs

4 GHZ is the highest clock rate that can be achieved in a cost

effective way. The solution for this problem is quite simple:

Put more CPUs onto one chip. But before we take a closer

Fig. 1.

The Code Morphing software mediates between

look on multi-core chips let′s review one of the technologies

x86 software and the Crusoe processor [6].

from the "pre-multi" area namely Simultaneous Multi

Threading or, like Intel likes to call their implementation,

from a special BIOS-like chip on the main board. Therefore

Hyper-Threading Technology.

the CPU can be `updated′ to learn new instructions and bugs

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and the L2 cache, along with some management logic are

shared.

C. Need for parallel programming

So does the simple equation two cores equals twice the

performance work? Sadly the answer to that question is no.

Some performance is lost due to the fact that two cores

produce slightly more overhead [12]. Caches needed to be

kept in sync, bus interfaces needed to be shared and in this

process quite a bit of the raw CPU power is lost. The biggest

problem however is software that hasn′t been created with

multi-core in mind, most notable games. This single threaded

Fig. 2.

Hyperthreading (red) can′t provide the same performance

software just uses one core no matter how many of them are

increase like real multi-core technology (yellow), but the

performance boost of around 25% is still quite impressive [10].

available in the PC: This problem can be softened by forcing

these applications to use different cores of the CPU. For

example a game can be forced to run on the second core while

A. Hyper-Threading Technology

all other applications run at the first core. However this is just

2*32 is also 64. Because AMD was faster than Intel in

a stop-gap solution. In the future, programs need to be

releasing 64bit for the mass market, Intel had to come up with

differently designed, that is they need to be multithreading.

something new in order to stay competitive. The impressive

Big tasks need to be chopped down into smaller ones which

marketing term Hyper-Threading was created and the first

can then be processed by different cores at the same time.

processor which used this technology hit the market in

Professional software often supports multithreading or can

February 2002 [9].

easily be adapted to do so but the rest of the software industry

In simple terms, Hyper-Threading Technology is multiple

needs to adapt to the new requirements to their software.

logical CPUs on one chip. When this technology was

Old software however, that isn′t designed for multi-core PCs

introduced this meant that an operating system which supports

and software which won′t be updated to use the available

multiple CPUs - and up-to-date operating systems do -

resources might often run slower on multi-core platforms.

suddenly has 2 CPUs to work with. However there aren′t

Because cooling is still a problem, multi-core CPUs are

really 2 CPU cores on the chip but 2 registers, another

clocked slower than their single-core siblings today. Software

interrupt controller and some basic management patterns. But

which uses only one core will therefore be limited to the power

as far as the operating system is concerned it can work with 2

this individual core has to offer. So if you are a gamer don′t

real CPUs. The amount of needed transistors is only raised by

buy a shiny new multi-core PC just yet.

around 1% and, according to Intel, the performance boost can

The question is not if multi-core will come but when it will

be as high as 35% [10].

come. Paul Otellini, CEO of Intel, estimates that in 2006

In practice it depends very much on what applications run on a

around 40% of the Desktop PCs sold will come with a dual-

CPU with Hyper-Threading, however at virtually no additional

core CPU [11]. It′s simply not practical to get more

cost the additional performance is quite impressive. As every

performance out of single-core CPUs and therefore multi-core

major CPU manufacturer is now focusing on real multi-core

is the future of CPU technology.

CPUs the fate of Hyper-Threading is already sealed. But in the

meantime it offers an easy way to increase the performance of

CPUs without too much of an effort.

V. VIRTUALIZATION

Virtualization is a technology that allows a platform to run

B. Multi-core CPUs

multiple operating systems in independent partitions at the

Not until too long ago a PC that had multiple CPUs was called

same time [13].

a server or a workstation and was very expensive. With the

This sounds like old news and in fact it is. Since the dawn of

recent speed improvements single core CPUs are producing

modern computing installing multiple operating systems on the

too much waste heat to be cooled effectively and speeding up

same PC was nothing to uncommon. However nowadays it is

those CPUs is very complex. So complex in fact that new CPU

possible to run Operating Systems at the same time. A typical

factories would′ve been needed to be built. To counter this

example would be someone using Linux and emulating

problem nearly every major CPU manufacturer has shifted

Windows in order to be able to play some games. In the last

their attention to building multi-core CPUs [11]. The first

few years Virtualization software like VMWare or Microsoft′s

wave of products was mostly dual-core. "2 are better than 1" is

VirtualPC has become quite popular. This software however is

also an effective marketing tool that can be understood even

often considered to be slow and memory hungry because a lot

by a complete layman. Unlike Intel′s Hyper-Threading

of the actual hardware has to be emulated in software. Other

Technology, multi-core CPUs have 2 real cores and often

hardware can′t be probably shared like RAM for example. The

those cores have their own L1 cache. Only the bus interface

virtual-machine software just takes a fix amount of RAM, no

matter what the OS that runs on it uses. Wouldn′t it be better if

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4

the virtual machine could just share the resources of the host

Code

MorphingTM

Software".

Whitepaper.

Available:

operating system? A lot of resources would be saved and

http://www.transmeta.com/pdfs/paper_aklaiber_19jan00.pdf

[7] A. Stiller, "Die ARM-Story - Von der kleinen Architektur zum großen

because not everything would need to be emulated the speed

Marktführer" (The Arm story ­ From the little architecture to the big

of the Virtualization software would increase dramatically.

marked leader) c

′t, german magazine for computer engineering

, vol.

This is exactly what Intel and AMD are currently working on ­

20/2002 pp. 70-73

hardware support for Virtualization.

[8] M. Markowitz et al. (2002-2006) "ARM architechture". From

Wikipedia,

the

free

encyclopedia

Available:

Intel calls its approach

Vanderpool Technology

[14].

http://en.wikipedia.org/wiki/ARM_architecture

The first processors implementing this technology have been

[9]

Intel Technology Journal

, Intel corp. volume 6, issue 1, ISSN

sold at the end of 2005 [15].

1535766X

Available:

AMD calls its Virtualization technology

Pacifica

and first

http://www.intel.com/technology/itj/2002/volume06issue01/vol6iss1_hy

per_threading_technology.pdf

processors with this technology are expected to hit the market

[10] M. Withopf, "Virtuelles Tandem - Hyper-Threading im neuen Pentium

in early 2006 [16].

4 mit 3,06 GHz" (virtual tandem ­ hyper-threading in the new Pentium

Pacifica can be compared to Vanderpool, however both

4 3.06GHZ) c′t

german magazine for computer engineering

, vol.

technologies are incompatible. Virtual machine producers have

24/2002, pp. 128-133

[11] R. Hülsenbusch, "Krieg der Kerne - Multicore-Techniken im Vergleich"

already announced they will support both approaches.

(War of the cores ­ multicore techniques in comparison) c

′t, german

In the end of 2006 AMD will introduce the next step of its

magazine for computer engineering

, vol. 04/2006, pp. 46-51 Available:

virtualization technology codenamed Hypervisor which will

http://www.heise.de/ix/artikel/2006/04/046/

make life for the manufacturers of Virtual Machine software

[12] E. Bonnert, A. Stiller, "Kernzeiten und Plattformierungen - Intel

Developer Forum Herbst 2004 " (core times and plaforms ­ Intel

even easier.

Developer Forum autumn 2004) c

′t, german magazine for computer

Other CPU and chipset manufacturers like ARM, ARC and

engineering

, vol. 20/2003, pp. 18-21

Texas Instruments are working on virtualization support or

[13] A. Shilov, (2005, Januar) "Intel Vows to Bring Virtualization to

have already released products with support for it.

Desktops in 2005 - Intel Speeds Up Vanderpool Roadmap". Online

The future of Virtualization is unclear. In the business and

Article

from

X-bit

labs

Available:

http://www.xbitlabs.com/news/cpu/display/20050120184415.html

professional market it will surely play an important part.

[14] R. Uhlig et al, (2005) "Intel Virtualization Technology". Article written

Testing software on many different platforms with just one PC

by Intel corp. employees for the IEEE magazine Available:

or consulting multiple servers onto one machine is becoming

ftp://download.intel.com/technology/computing/vptech/vt-ieee-

more and more popular and the hardware support will make

computer-final.pdf

[15] A. Stiller, "Prozessorgeflüster- Von Dresden bis Babylon" (processor

life easier a lot. This kind of application doesn′t really play an

whispering ­ From Dresden to Babylon) c

′t, german magazine for

important part for the consumer market and it remains to be

computer engineering

, vol. 25/2005, pp. 20-21

seen if this technology will really kick of or if it will just be

[16]

Advanced Micro Devices - AMD

, AMD I/O Virtualization Technology

one of many technologies that are there for their own good, not

(IOMMU) Specification, PID 34434 Rev 1.00 - February 03, 2006

Available:

http://www.amd.com/us-

being used by anyone.

en/assets/content_type/white_papers_and_tech_docs/34434.pdf

VI. CONCLUSION

The gigahertz mania seems to be finally over therefore the

manufacturers need new arguments to sell their products.

We′ve given a small introduction on what′s going on in the

CPU market and these technologies will surely play an

important part in the future.

REFERENCES

[1] A. Stiller, "Doppelbreit ­ 64 Bit kontra 32 Bit" (double-wide ­ 64 Bit

contra 32 Bit) c

′t, german magazine for computer engineering

, vol.

20/2003, pp. 106-112

[2] A. Stiller, "Prozessorgeflüster- Intel mit AMD Inside" (processor

whispering ­ Intel with AMD Inside) c

′t, german magazine for
computer engineering

, vol. 05/2004, p. 24

[3] C. Windeck, "Diät Prozessoren ­ Mobil-Prozessoren im Desktop-

Einsatz" (Diet Prozessors ­ mobile prozessors in desktop use) c

′t,
german magazine for computer engineering

, vol. 06/2004, pp. 164-174

[4] A. Stiller, " Die Quelle des Jordan - Optimierte Mikroarchitektur für

unterwegs" (The spring of the Jordan ­ optimised microarchitecture on

the move) c

′t, german magazine for computer engineering

, vol.

07/2003, pp. 122-123

[5] M. Schmidt, "Intel Centrino Technologie: Pentium-M-Prozessore".

Online

article.

Available:

http://www.pc-

erfahrung.de/Index.html?NotebookCPUIntelCentrino.html

[6] A.Kleiber, (2002, Januar) "The Technology Behind CrusoeTM

Processors - Low-power x86-Compatible Processors Implemented with

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