AMD Multi-Core ProcessorsProviding Multiple Benefits For The Future

variations this year. In 2007 the chipmakersexpect to introduce several multi-corechips, beginning with quad-core offerings.

We discussed Intel’s multi-core proces-sors in the January 2006 issue of CPU

(page 50). This month, we’ll focus on whatAMD has planned for 2006 and beyond.

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In April 2005, AMD released its firstdual-core chip aimed at the server andworkstation market, the Opteron proces-sor. There are several Opteron dual-core90nm processors ranging in clock speedsfrom 1.6GHz to 2.4GHz.

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By now you probably have heard ofdual- and multi-core processors.Both AMD and Intel released

dual-core chips in 2005, and both haveplans to release dozens more dual-core chip

Direct Connect Architecture vs.Legacy Systems

Source: AMD

Direct Connect Architecture lives up to its name by providing a direct connection between the processor, the memory controller, and the I/O area to improve overall system performance. AMD has used Direct Connect Architecture

for the past few years in its single-core chips.But now AMD has extended the use of Direct Connect Architecture to

connect the cores on a dual- or multi-core chip die and to connect eachcore to its memory controller. ▲

When using a dual-processor x86 legacy architecture,however, two processors then have to share the samememory control hub, which creates bottlenecks in datatransfers at the FSB. The two processors aren’t connected,either, which can lead to latency problems.

With multi-core architecture, each core on the chip has its own memory con-troller, which significantly improves memory performance. Using Direct ConnectArchitecture to make a connection with the memory controller eliminates mostbottlenecks and makes multitasking easier. Also, connecting the processor corestogether lets data flow freely and reduces latency problems.

As with other families of AMD processors, a larger model numberfor an Athlon 64 X2 dual-core chip equals better software perfor-mance on that processor vs. those with smaller model numbers.Each Athlon 64 X2 90nm chip listed here runs at 1.35 to1.40V anduses a Socket 939 socket. ▲

Athlon 64 X2 Dual-Core Chips

Source: AMD

Processor Clock Speed L2 Caches Max Temp Price*(GHz) (°C)

3800+ 2 512KB (x2) 71 $328

4200+ 2.2 512KB (x2) 65 $408

4400+ 2.2 1MB (x2) 65 to 71 $507

4600+ 2.4 512KB (x2) 65 $643

4800+ 2.4 1MB (x2) 65 $803

*Price as of January 2006, for direct AMD customers in 1,000-unit quantities

The first desktop dual-core processorfrom AMD appeared in May 2005 underthe Athlon 64 X2 brand name. AMD hasseveral variations of its Athlon 64 X2processors. (See the “Athlon 64 X2 Dual-Core Chips” chart for some examples.)

AMD’s first dual-core processors fornotebooks and the mobile market shouldappear sometime in the first half of 2006.Multi-core processors from AMD shouldinitially appear in 2007.

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As AMD releases its dual- and multi-core chips, the company will introduceand improve upon several technologies.

Cool’n’Quiet. When AMD’s systemis running Cool’n’Quiet technology, it adjusts the speed of the system fanand the voltage and clock speed of thecores on the processor based on the system case temperature. (See the“Cool’n’Quiet Technology” sidebar formore information.)

Direct Connect Architecture. AMDplans to enhance this technology in dual-and multi-core chips to improve datatransfer connections among the cores onthe chip. (For more information see the“Direct Connect Architecture vs. LegacySystems” sidebar.)

HyperTransport 3.0. AMD and theHyperTransport Consortium continue todevelop HyperTransport 3.0, which mayoffer about three times the bandwidth ofversion 2.0. HyperTransport 2.0 can offeraggregate bandwidth up to 22.4GBps. Aswith previous versions of the technology,HyperTransport 3.0 will offer direct con-nections between the CPU and the I/Oarea. The new version will provide directconnections among the cores in the dual-and multi-core chips.

AM2 socket technology. During 2006AMD will release new dual-core chips thatuse an AM2 socket technology, which uses a different pin configuration thanAMD’s 939 socket. Customers who choose

dual-core chips and motherboards that sup-port the AM2 socket will then be able toupgrade to a quad-core chip, which alsowill use the AM2 socket when AMD intro-duces it (scheduled for 2007).

Pacifica technology. AMD’s Pacificatechnology will improve performance, relia-bility, and security for virtualization hard-ware environments. It should appear in thefirst half of 2006 and use dedicated transis-tors to deliver the new features while run-ning as part of dual- and multi-core chips.(See the “Using Pacifica Technology” side-bar for more information.)

Presidio technology. Presidio technolo-gy will give users advanced security fea-tures at the chip level. Although AMD hasreleased very little information about howPresidio will work or when it may appear,think of Presidio as creating a protectedarea on the processor where it can storeand process sensitive data. ▲

by Kyle Schurman

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Inside AMD’s Dual-Core Processor

Source: AMD

CPU 1 and CPU 2. The dual AMD64cores on this chip can run 32- and64-bit computing simultaneously.

64KB I-Cache.The L1 instructioninternal cachesoffer low latency.

1MB L2 Cache.The L2 second-level internalcaches offer low latency.

72 bit. This DDR400 memory interface provides data transfer rates up to 6.4GBps.

Link 1/2/3. These three links connect the I/Oarea to the processor usingHyperTransporttechnology.HyperTransportalso can provide ahigh-speed link among processors in amulti-processorconfiguration.

System Request Queue.This area manages howeach core accesses thecrossbar switch.

64KB D-Cache. The L1 datainternal caches are low latency.

Crossbar. The crossbar makes the connection between each core and the I/O area and memory interfaces. The crossbar is a key component of the chip,letting the core access the data it needs torun software and perform calculations.

Integrated DDR Memory Controller. This featurereduces the latency associated with accessingmemory vs. using an FSB architecture to accessmemory. Each core has its own memory controller.

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When AMD designed the AMD64 processor duringthe late 1990s, the company had dual- and multi-core technologies in mind. Such planning has madeAMD’s evolution into multi-core products an easierprocess. For example, AMD designed some of itscurrent dual-core processors to fit in the same sock-ets as its single-core offerings, such as the 940-pinOpteron processor and the 939-pin Athlon 64processor. Also, all of the software that runs underx86 and AMD64 processors will work with AMD’smulti-core processors; no coding changes needed.

During the past couple of years, AMD hasmoved away from releasing timelines listing detailedplans for its future processors complete with codenames. Instead, AMD’s beginning to give more gen-eral names to overall chip projects, rather than split-ting out code names for individual chip plans.

K8 Dual Core. This is the server and workstationOpteron dual-core chip that debuted in April 2005.

K8L. This quad- or eight-core chip will poten-tially follow K9 in 2007 or 2008, although little isknown about this project.

K9. Due to launch in 2007, K9 should be aquad-core chip appearing under the Opteronbrand name in servers. It will feature a new coredesign, DDR3 memory, and contain L3 cache,which will let server designers build systemsusing up to 32 processors. (Current cache set-tings allow for only eight processors per system.)AMD road maps indicate quad-core chips fordesktops will initially appear in 2008.

Santa Ana. This dual-core chip should be partof the Opteron 100 series, use an AM2 socket, andappear in the second half of 2006.

Santa Rosa. Expected to appear in the firsthalf of 2006, this dual-core chip should be partof the Opteron 800/200 series.

Taylor. Aimed at the mobile market, thisdual-core chip should launch under the Turion64 brand name. Taylor should appear early in 2006, use an AM2 socket, and support DDR2 memory.

Toledo. This is the desktop Athlon 64 X2dual-core chip that debuted in May 2005.

Trinidad. Due sometime in 2006 and intend-ed for the mobile market, this 90nm AMD64dual-core chip will use an AM2 socket.

Windsor. This 90nm dual-core chip shouldappear early in 2006, use an AM2 socket, andsupport DDR2 memory. ▲

Sources: AMD, AMDboard.com, and Endian.net

AMD’s Multi-Core Processor Future

Multi-Core Benefits

Source: AMD

When multitasking, users willexperience fewer bottlenecksthan with single-core systems.

Improved performance is pushing the migration to multi-core proces-sors, but that’s not the only reason: Multi-core processors are alsoappearing out of necessity.

The technological advances that have driven manufacturers to double thenumber of transistors on a chip every 18 to 24 months (fulfilling Moore’sLaw) are beginning to reach their physical limits. Chipmakers have continu-ally shrunk the manufacturing process for transistors over the years. They’recurrently shifting the manufacturing process from 90 to 65nm, which letsthem squeeze more transistors onto each chip. An IDC report, however,says that once the chip manufacturing process reaches about 16nm in size,the processors won’t be able to control the flow of electrons as the flowmoves through the transistors. This means that transistors eventually willreach a size where chipmakers can no longer make them smaller. Eversmaller and denser transistors on a chip generate more heat, causing pro-cessing errors. But multi-core processors can improve computing powerand limit some of the problems that shrinking transistors are causing.

The one drawback to multi-core technology is the increase in costfor systems and chips. However for many users the benefits will out-weigh the cost factor.

• Users can add more computing power without the cost of addinganother computer. This feature especially benefits commercial users,letting them add more processing power without adding more servers.By adding fewer servers, companies will need less real estate to holdthe servers. Also, the costs of electrical power to run those servers andthe cost of cooling the servers will decrease.

• For those who compile software code, dual- and multi-core processorsseriously improve compiling efficiency. AMD says its current dual-coreprocessors reduce the time needed to compile code by as much as 50%compared to a single-core processor.

• Game developers can add more features and cutting-edge graphics totheir games because dual- and multi-core chips will more easily andefficiently handle multithread software designs.

• Multi-core processors don’t consume more power or generate moreheat vs. a single-core processor, which will give users more pro-cessing power without the drawbacks typically associated with such increases. ▲

When running two processor-intensive applications, each onecan access its own core, whichmakes it easier to burn a CD whilerunning a virus scan, for example.

When running a single application, dual-cores can share the processing load,improving overall system performance.The system also can shut down portionsof the cores that aren’t in use, savingpower and generating less heat.

A processor withtwo or morecores worksfaster and moreefficiently than asingle-coreprocessor forseveral reasons:

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Virtualization uses software to share and manage workloads at theprocessor level, making it appear as though the server contains a multi-processor system. A single server can run multiple OSes and applicationsusing virtualization. Implementing the idea of virtualization also meanscompanies don’t need to have as much hardware performance capabilityheld in reserve among their servers to meet peak situations.

By building virtualization technology inside the processor, as AMD willdo with Pacifica technology, multi-core processors could then providebetter overall performance vs. a single-core processor trying to run virtu-alization. Pacifica, which AMD will introduce later this year, would simplifythe implementation of virtualization and let it more easily take advantageof the multiple cores on a processor. ▲

In a system without Pacificatechnology, the x86 processorhardware contains no virtu-alization capabilities. When cre-ating a virtual machine in thistype of system, the virtualiza-tion software must manage theresources between the host OSand the guest OS. Because thisextra layer causes additionaloverhead and complexity, ap-plication performance suffers.

With Pacifica running on an AMDdual- or multi-core processor, therewould be fewer layers and lesscomplexity, improving applicationperformance. Pacifica would useHypervisor as its virtualization software, which would manage thevirtual machines. Hypervisor alsowould track the availability of physical hardware, letting applications take advantage of thehardware as it becomes available.

Using Pacifica Technology

Cool’n’Quiet Technology

Source: AMD

Source: AMD

AMD has carried its Cool’n’Quiet tech-nology into its dual-core offerings. It cutsdown on the heat and noise that a proces-sor generates and helps the processor useless power by cutting back on the its clockspeed and voltage when the computeruser’s demands are less. AMD says usersrarely will notice any system performancedegradation while using Cool’n’Quietbecause it can adjust the clock speed andvoltage up to 30 times per second.

To run Cool’n’Quiet, a PC needs aheatsink with a variable speed fan, whichadjusts the fan’s rotation speed based onthe computer case’s air temperature. Thesystem also needs a Cool’n’Quiet driver.

When running Cool’n’Quiet, the CPUoperates in one of three basic states: max-imum, intermediate, or minimum. The in-termediate state can have more than onesetting, and the more settings available,the more flexibility the processor has tosave power and reduce heat.

For example, AMD’s Athlon 64 3500+processor can operate in one of fourstates, measured by the clock speed andvoltage in use.

Maximum: 2.2GHz; 1.5VIntermediate A: 2GHz; 1.4VIntermediate B: 1.8GHz; 1.3VMinimum: 1GHz; 1.1V

The minimum state works well forcomputing tasks involving a lot of idleprocessor time, such as word process-ing and emailing. Intermediate stateswork well for tasks requiring a lot ofcontinuous processor access, such assystem scans with no other tasksoccurring or processes running.

As the Cool’n’Quiet driver workswith the motherboard to measure sys-tem temperature and current processorworkload (based in part on the type ofsoftware a user is running), it placesthe processor in the most appropriatestate. At the same time, the variablespeed fan speeds up or slows down tomatch the change in the processor’sstate. As the processor decreases itsclock speed and uses less power, theprocessor and power supply generateless heat. As the temperature in thecase falls, the system can decrease the fan’s rotation speeds, leading toless noise from the fan and from air turbulence.

In contrast, when a user cranks upsystem performance to the maximumstate, Cool’n’Quiet increases the fan’srotation speed to remove the addition-al heat it now generates, increasing system noise. ▲