Dualcore Processor

8/7/2019 Dualcore Processor

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INTRODUCTION:

´ Dual-core microprocessors are currently the center of

attention in computing design. There is a definite shift

away from ever higher frequencies to multicore

processors to meet higher-performance requirementswithout pushing power consumption ,beyond what can

be tolerated in many applications. It·s not just about a

drastic improvement in the speed of different

applications, but a completely new digital experience.



WHAT IS THE µDUAL CORE

TECHNOLOGY¶?

Dual core technology refers to two individual microprocessors ona single die cast chip.

Tasks can be carried out in parallel streams, decreasing processing time.

This is referred to as thread-level parallelism (TLP). When TLP is accomplished in a single CPU through dual core

technology, it is called chip-level multiprocessing (CLM).

In dual core CPUs, each microprocessor generally has its ownon-board cache, known as Level 1 (L1) cache. L1 cache

significantly improves system performance, because it is muchfaster to access on-chip cache than to use random accessmemory (RAM). L1 cache is accessed at microprocessor speeds.



CONCEPTUAL DIAGRAM OF A DUAL-CORE

CPU, WITH CPU-LOCAL LEVEL 1 CACHES,

AND SHARED, ON-CHIP LEVEL 2

CACHES.

Thiscache

(L2) issharedby boththecores.



In simple terms, dual-core refers to a CPU thatincludes two complete execution cores per physicalprocessor onto a single integrated circuit (silicon

chip). It combines two processors and their cachesand cache controllers onto a single integratedcircuit (silicon chip). It is basically two processorsresiding side-by-side on the same die.

Continued«



DIFFERENCE BETWEEN µDUAL

PROCESSOR¶ AND µDUAL CORE¶

SYSTEMS´ Dual-processor (DP) systems are those that contains two

separate physical computer processors in the samechassis. In dual-processor systems, the two processors caneither be located on the same motherboard or on separate

boards.

´ In a dual-core configuration, an integrated circuit (IC)contains two complete computer processors. Usually, thetwo identical processors are manufactured so they resideside-by-side on the same die, each with its own path to thesystem front-side bus. So, Multi-core is somewhat of anexpansion to dual-core technology and allows for morethan two separate processors.



PERFORMANCE/WATT TRADE OFF

One of themostimportantdesignparameter



´ ACPower(PAC)= nCV2f

Where,

´ n is the fraction of active switching transistors

within the device´ C is capacitance of all of the gates

´ V is the transistor voltage

´ f is the core frequency



SIMPLE PICTORIAL

REPRESENTATION OF AN

INTEGRATED CORE :



INCENTIVES :

Hyper threading : It is the technology developed by

Intel that enables multithreaded software

applications to execute thread in parallel on dual-

core processor.

In brief, hyper threading allows for a single

physical processor to appear to the operating

system as two logical processors.

According to Intel, the implementation of this

technology the processor speed performance

improves 15-30%



´ Leakage Problems : Another component to thisequation is the leakage or static power that is alsocommonly referred to as the DC power component. It iscaused due to the leakage current present when thetransistor is in an off state.

´ Development Motivation : The demand for morecomplex and capable microprocessors causes CPUdesigners to utilize various methods of increasingperformance. A combination of increased available spacedue to refined manufacturing processes and the demand

for increased TLP led to the logical creation of multi-coreCPUs.



´ Commercial incentives

´ Several business motives drive the development of dual-corearchitectures. Since SMP designs have been longimplemented using discrete CPUs, the issues regardingimplementing the architecture and supporting it in softwareare well known. Additionally, utilizing a proven processing

core design (e.g. Free scale's e700 core) without architecturalchanges reduces design risk significantly. In order tocontinue delivering regular performance improvements forgeneral-purpose processors, manufacturers such as Intel andAMD have turned to multi-core designs, sacrificing lowermanufacturing costs for higher performance. An especially

strong contender for established markets is to integrate moreperipheral functions into the chip .

´ Also Dual core chips take up less real estate on themotherboard, and have greater cache coherency.Moreover, multicore reduces bandwidth and latency

bottleneck s.



PERFORMANCE VS. POWER

It can be easilyseen in thegraphicalrepresentation, thedual corecombination is themost optimizedsolution available.



´ The fact that higher-performance superscalar discreteprocessors can introduce a hot spot exceeding 60 Won a small area makes such devices impractical in an

embedded environment, where the power budget istypically limited to 10 W per core. In addition, suchhigh-power devices cannot be cooled using a passiveheat sink alone; a fan must be mounted on the device,and fans that meet the general embedded market·s

minimum requirements of 10-year reliability areexpensive.



´ Another way to improve performance is to providetwo memory controllers, one for each core. Insteadof doubling the frequency, which would requirememory that operates at a speed not yetcommercially available, the path is widened at the

original frequency, following the principle of parallelism as demonstrated by the secondinstantiation of the core. Interleaving the physicalmemory across two controllers could radicallyreduce the latency for some shared-memory SMP

applications by allowing twice the number of openpages allowed by a single controller.



´ Common Misconceptions

´ Many people commonly assume that the

multithreading benefits of a dual-core processor will

translate into a better user experience whilemultitasking. This is not generally true, as many user

applications (such as word processing applications)

spend most of their time in an idle state; a person

can't switch contexts faster than a computer.



ADVANTAGES OF DUAL CORE

TECHNOLOGY

Proximity of multiple CPU cores on the same die have theadvantage that the cache circuitry can operate at a much higherclock rate than is possible if the signals have to travel off-chip,

Assuming that the die can fit into the package, physically, themulti-core CPU designs require much less PCB space thanmulti-chip SMP design.

A dual-core processor uses slightly less power than two coupledsingle-core processors, principally because of the increasedpower required to drive signals external to the chip and becausethe smaller silicon process geometry allows the cores to operateat lower voltages.

In terms of competing technologies for the available silicon die

area, multi-core design can make use of proven CPU corelibrary designs and produce a product with lower risk of designerror than devising a new wider core design.



ADVANTAGES (CONTD.) :

Increased computing capabilities.

New benefits for both home and business.

Unlimited opportunities to explore avenues inthe digital enterprise.

Increased productivity of offices

Digitalization of homes.



DISADVANTAGES OF DUAL

CORE TECHNOLOGY

´ In addition to operating system (OS) to support,adjustments to existing software are required to maximizeutilization of the computing resources provided by multi-core processors. Also, the ability of multi-core processors to

increase application performance depends on the use of multiple threads within applications.

´ They are more difficult to manage thermally than lower-density single-chip designs.

´ From an architectural point of view, ultimately, single CPU

designs may make better use of the silicon surface areathan multiprocessing cores, so a development commitmentto this architecture may carry the risk of obsolescence.



CONCLUSION

Historically, scaling processor frequencies has giventhe required performance without too much concern aboutpower consumption, although it has always been desirablefor microprocessor designers to strike a balance betweenpower and performance. The balance can be achieved byopting for parallelism using dual cores rather than an even

higher-performing discrete core. Integrating memorycontrollers on chip vastly reduces latencies and increasesbandwidths, historically two of the largest bottlenecks inMP systems and in microprocessors in general. Integrateddual-core devices offer the ideal balance and are thereforea promising solution for low-power embedded applications.



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Dualcore Processor