Report on Quad Core Processors 2

8/4/2019 Report on Quad Core Processors 2

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Quad Core Processor

Technology Written by –Zameer Rahman



Quad Core Processor 2011

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Index

Abstract Page-3

Road to Quad Core Page-4

Quad Core Processor Page-5

What is quad core? Page-6

Quad Core Chip Design Page-8

Quad Core Processors

Architecture

Page-10

Quad Core Processing Page-11

Features And Benefits Of INTEL

Quad Core Processor

Page-18

Conclusion Page-21

References Page-21




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Abstract

The evolution of computer processor designpassed many stages in last few decades. Stillthe world’s hunger for better performance in

computing is never satisfied. The need for morepowerful processors is increasing due to thecomplexity of our computing tasks and demand ofcomputers in the mass market. As the softwareapplications becoming more sophisticated thedemand for higher performing processors is

becoming inevitable in our life. Nowadays,Computer is integrated in every aspect for ourlife. From Wall Street to local shopping storessoftware applications are being used. Computeris storing and protecting all kinds of data andvia computer networks everyone is connected tothe cyber space. Today we can do a lot of thingsby using computers which were considered as

sciences fictions in earlier decades. In nearfuture software applications might create real-world simulations so vivid that people will nolonger identify whether it is real orartificial.

Now-a-day in the field of computer architectureno one is building a much faster sequentialprocessor. The attention is shifted to multiple

processors per chip in order to cope up withprocessing needs. The multi-core processors areleading the computing technology now. Quad coreprocessor is one of the greatest forms of multi-core processor architecture. The quad coreprocessor is turned single-core processors into




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ancient relic by providing better performanceand productivity. Since the attention shifted tomultiple processor per chip the maximum powerdissipation in air cooled chips are decreased.The exploiting of instruction level parallelismis done more efficiently and the memory latencyis changed dramatically.

II. Road to Quad Core

If we study the evolution of quad coreprocessor’s the first thing we will notice thatthe Moore’s Law isn’t really dead. In 1965,

Intel co-founder Gordon Moore stated that“The number of transistors and resistors on a

chip doubles every 18 months.” This famous

comment in regarding the pace of semiconductor

technology is considered at as Moore’s Law. Thattime there were approximately 60 devices on achip. After four decades later when we see Intelplaced 1.7 billion transistors on its Itaniumchip we can hardly deny this law anymore.It means that Intel is providing us bettercomputers at lower price.At first hyper threading is introduced to theworld of computing. It used thread levelparallelism where each tread acted like aseparate processor with its own instruction anddata. After some time, the introduction ofmulti-core architecture gave birth to dual coreprocessors, where there are two separate coresin the same die of the processor chip, each with




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its own cache. In the dual core processor thedoubling of core lead to doubling of performancein the same clock cycle. Intel core 2 duo wasthe ultimate version of dual core processors.

The same multi-core architecture was takenfarther which gave birth to the Quad CoreProcessor, where there are two dual coreprocessors on the same die which is equivalentof getting four microprocessors in one.

The quad core processors are built on Intel’s

45nm manufacturing technology where hafnium-infused Hi-k transistors are used. The processorperformance gets better by doubling thetransistor density. The efficiency and speed ofquad core processor is better than all of theprevious generation processors and the cachesize is also increased by up to 50 percent.Infect these new Intel Core 2 Quad Processors

use the same energy but deliver even betterperformance.

III. Quad Core Processor

Quad Core processor is actually two dualcore processors in one chip. In Core 2 Quadprocessors the dies were similar to that of Core2 Duo processor but the number of core being wasdoubled .There are four execution cores in onepackage i.e. Quad Core Processor. Here each core




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runs at lower frequency and handles incomingdata strings simultaneously to improveefficiency. It’s like four heads are workingtogether, when one is executing the other threecan be accessing the system bus or executing itsown code. Intel Core micro-architecture makessure that each of the four cores is executingperfectly, So that more instructions can becarried out per clock cycle. The commandsexecuted quickly due because of shorter andwider pipelines and improved bus lanes move datathroughout the system faster. This quad-core

processor provides multi-core processing andmore parallel computing. To utilize a quad coreprocessor, the operating system must be able torecognize multi-threading and the software musthave simultaneous multi-threading technology(SMT) written into its code. SMT enablesparallel multi-threading wherein the cores areserved multi-threaded instructions in parallel.

Without SMT the software will only recognize onecore. Adobe Photoshop is an example of SMT-awaresoftware. SMT is also used with multi-processorsystems common to servers.

IV. What is quad core?

There are three components in aprocessor. They are the core, the die and thepackage. The first one i.e. the core executesprocessing tasks. The second one is the silvertab we see on the top of a processor is called




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the die. The core is fitted inside the die. Thetwo of them is fitted inside the third one i.e.the package. It is the green material capped bythe heat spreader on top, and laced with pins onthe bottom. It is important to know that thenumber of cores can scale independently of thedies.

Figure1. Here we can see the progress: One larger die is shrunk andplaced with a twin on the same package. Then a single-die/dual core die isproduced, and the cycle repeats ad infinitum with more cores per die.




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V.Quad Core Chip Design

There are basically two approaches to madequad core chips. The first approach is calledthe inelegant one aka “multi chips”. In this

approach two processor cores is placed insidea single die. Then the two single dies areplaced inside another die. The manufacturing

process of dies of single processors are beingimproved and modified for this purpose. Therethree advantages of this approach.

1. This is the very first approach of

creating quad core chips.

2. It created the demand for Quad Core

processors.3. The manufacturing cost of multi-core

chip is inexpensive.

There are two disadvantages of this technique.

1. It produces too much heat in CPU becausethe two die will radiate double heat

2. The logic used to price the chip is veryexpensive

The other approach to make quad core chips isknown as the native way or the monolithic way.In this approach of chip design four individual




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cores are fitted inside one single processordie. The benefit for the manufacturer in thiscase has three parts.

1. World’s first “true” quad core chip is

actually created in this approach

2. The heat radiation is problem is solvedbecause of using single die. So monolithic

chips run much cooler and the “multi-chips”.

3. The four cores can communicate with eachother simultaneously at speed of the

processor itself.

Figure2: in this scenario, we see that the cores on the “native” QC chip are capable of talking

directly to one another. On the “inelegant” solution, while still quad core, it must endure thlag

of sending information across the system bus if one half of the chip needs to talk to the other




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VI. Quad Core Architecture

Figure 3: Quad Core Intel Processor Architecture

As we can see in the figure two cores aresharing one L2 cache therefore there are 2caches for the four cores. The size of one L2cache is 4MB so the total L2 cache is 8MB on the

processor. The L2 memory cache is shared,meaning that both cores use the same L2 memorycache, dynamically configuring how much cacheeach core will take. One core may be using 3.5MB while the other 512 KB (0.5 MB), contrasted




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to the fixed 50%-50% division used on previousdual-core CPUs.

The L2 caches are connected via front-side bus

(FSB) with each other. If core 1 wants sharedata with core 4 then it will communicate viathis FSB. The FSB between the processor and thechip still runs at 1066 MHz by default aswell. On Intel quad-core CPUs the Front Side Busis used for accessing the RAM memory, otherdevices present on the PC and for thecommunication between each pair of cores. The

communication between each pair of cores can bedone up to 8 GB/s.

VII. Quad Core Processing

Quad core processing requires the precise union

of all the components. The first stage ishardware support. Motherboards and BIOS updatesneed to recognize the CPU. If it can’t recognize

then the motherboard won’t be able to tell thecomputer to which process it should run.Therefore the quad core must synchronize withthe hardware of the computer.

The next step is get recognized by the operating

system . The operating system must recognize thatthere is more than one core inside a chip. Theold operating system was not created for quadcore processors so we cannot use those versions.But currently Microsoft and virtually all




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flavors of Linux distributor have fully endorsedthe power of multi-core chips, allowing today’sversions of Windows and Linux to support chipswith two, four, eight, or even sixty four cores.

The last step on the road to quad is the mostimportant but also the hardest one. It isthe software that runs on the chips. Just likethe operating system the software has torecognize quad core too. When the software iscapable of running in quad core processor ittells the hardware what it needs, then the

hardware pass the command to the motherboard, atlast the motherboard tells the processors whatto do. Unfortunately the process is not assimple it seems. The concept which let asoftware to run in a multi-core chip is calledthreading. A tread is a separate processor withits own instruction and data. It divides theworkload between multiple or multiple physicalprocessors.

Multi treading may need to process manydifferent stages of a single program or it mayinvolve many programs running at the same time.Like for example, if we are running a mediaplayer, a browser and an instant messenger atthe same time. So the work load will be dividedbetween different cores like one core will

handle the media player, another browseroperation and vice versa.

On the other hand an application may performmany tasks at once; each task relies on anotherto make it work. For example if we are running a




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video game then there are character movement,background movement, artificial non playingcharacter movement and the sound effects allruns at the same time. So multi threadingdivides the operation and let the video game runwithout any interruption almost instantly.

Two types of threading are used in quad coreprocessing one is called broad treading and theother is called fine treading.

Figure 4 here we see the program as the red and

blue lines entering the dual core processor.

It’s broad -threaded multi-threaded application,




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so the processor workload is simply split in

half each.

In the above figure broad threading is takingplace. In broad threading the workload isdivided between the two cores and the processesare set to stay synchronized with each other.But since it is only designed for dual-coreprocessors it is an inelegant solution for multitreading in a quad core processor. The

horsepower provided by quad core processor ismore than broad threading can use, so there iswastes of unused clock cycles.

Fine-grained threading resolves these problemsby optimizing the full potential and horsepowerof the quad core processor. In this threadingthe developer carefully analyzes all thepossible steps of the program at any given time

and predicts hazards or interrupts. They dividethe programs or each possible task by keepingthese analysis and prediction in mind in orderto truly maximize the horsepower of theprocessor. In broad threaded there are unusedclock cycle and unused cores but in the finegrained threaded apps each core will always dosomething in every clock cycle.




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Figure 5 A fine-grain multi-threaded processes

generates hundreds of individual tasks, each one

directed specifically to an underutilized core

As we can see in the figure each half of theprocessor would be receiving two sets of red andblue arrows with a lattice of processes. This ishow fine grain threading is done.

The Intel programmers have found the optimumsolution for the threading of quad coreprocessor. In the quad core processor eachthreads acts like a separate processor with itsown instruction and data. Each treads acts as auniprocessor (the following diagrams)




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Figure6a and 6b : quad core processor threading




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Figure 7: Four CPU’s available in the taskbar

In the taskbar CPU usage history shows fourdifferent histories as if four differentcomputers are working. That is the exact proveof quad core multi-threading architecture.




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VIII. FEATURES AND BENEFITS OF INTEL

PROCESSOR

1. Intel ® Wide Dynamic Execution

It delivers more instructions per clockcycle which improves the execution speed andenergy efficiency. Here each of the four corescan execute four full instructionssimultaneously.

Its new capability called Macro-Fusioncombines certain common x86 instructions into asingle instruction that is executed as a singleentity.

2. Intel ® Smart Memory Access

It improves system performance by optimizingthe use of the available data bandwidth from thememory subsystem and hiding the latency ofmemory accesses. It ensures faster data transferin close location to reduce latency and improveefficiency and speed.

It also includes an instruction pointer-based prefetcher that “prefetches” memory

contents before they are requested so they canbe placed in cache and readily accessed whenneeded. It keeps the pipeline full and improvesinstruction throughput and performance.




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Intel Smart Memory Access includes an importantnew capability called " memory disambiguation,"which increases the efficiency of out-of-orderprocessing by providing the execution cores withthe built-in intelligence to speculatively loaddata for instructions that are about to executebefore all previous store instructions areexecuted.

3. Intel ® Advanced Smart Cache

It is optimized for multi-core processors,

providing higher performance with a moreefficient cache subsystem. It accelerates abroad range of multimedia, encryption,scientific and financial applications bysignificantly improving performance whenexecuting Intel® Streaming SIMD (SingleInstruction stream M ultiple Data stream)Extensions (SSE/SSE2/SSE3) instructions.

4. Intel ® Advanced Digital Media Boost

Intel® HD Boost, implemented on 45nmprocessors, offers new Intel® Streaming SIMDExtension 4 (Intel SSE4) instructions for evengreater multimedia performance and faster high

definition video editing and encoding.




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5. Intel Virtualization Technology (Intel

VT)

It allows one hardware platform to functionas multiple “virtual” platforms. Intel ® VT

improves manageability, limiting downtime andmaintaining worker productivity by isolatingcomputing activities into separate partitions.

6. Intel ® 64 Architecture

It allows the processor to access largeramounts of memory. Intel 64 architecture

improves performance by allowing systems toaddress more than 4 gigabytes (GB) of bothvirtual and physical memory.

7. Execute Disable Bit

It provides extended virus defense whendeployed with a supported operating system.

8. Digital Thermal Sensor (DTS)

It provides for more efficient processor andplatform thermal control improving systemacoustics.

9. Intel® Intelligent Power Capability

It is designed to reduce power consumptionand design requirements. This feature managesthe runtime power consumption of all theprocessor's execution cores.

10. Intel Designed Thermal Solution for

Boxed processors




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This includes a 4-pin connector for fan speedcontrol to help minimize the acoustic noiselevels generated from running the fan at higherspeeds for thermal performance. Fan speedcontrol technology is based on actual CPUtemperature and power usage.

IX. Conclusions:

"Kentsfield" was the first quad core processor.After that Quad core processors have evolvedmany times since its invention. The latest Intelcore 2 quad processors provides an evolving setof threaded multimedia applications, includingdigital content creation will shine as users areable to complete tasks faster. Game play canachieve even greater visualization and realismas tasks such as artificial intelligence (AI),physics and rendering can be distributed across

each of the four complete execution cores andrun in parallel. With all these features multi-tasking environments can be expanded like neverbefore. Users can stream high-definition contentwhile playing a high-frame rate game, or runmultiple complex databases while developingprofession content and running virus protectionsoftware in the background.

X. Reference:

Retrieved August 20, 2011, from: http://tech.icrontic.com/articles/quad_core/(all the web images)

http://en.wikipedia.org/wiki/List_of_Intel_Core_2_microprocessors




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