14-06-2009, 09:09 AM
A SEMINAR REPORT ON INTELATOM
Submitted by : BALU GEORGE MICHEAL
COMPUTER SCIENCE & ENGINEERING
SCHOOL OF ENGINEERING
COCHIN UNIVERSITY OF SCIENCE & TECHNOLOGY,
KOCHI-682022
NOVEMBER 2008 2
SCHOOL OF ENGINEERING
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
KOCHI-682022
ABSTRACT
Intel Atom is the brand name for a line of x86 and x86-64 CPUs (or microprocessors) from Intel, previously code-named Silverthorne and Diamondville processors, designed for a 45 nm CMOS process and intended for use in ultra-mobile PCs, smart phone and other portable and low-power applications. This is Intelâ„¢s smallest processor built with the world's smallest transistors. The Intel Atom processor is based on an entirely new design, built for low power and low cost. This small wonder is a fundamental new shift in design, small yet powerful enough to enable a big Internet experience in the devices mentioned above. Atom provides new magnificent features like Hyperthreading, a power optimized front side bus, a low Thermal Design Power, the C6 mode which Is the Intel enhanced deeper sleep mode etc,
1. INTRODUCTION
"This is our smallest processor built with the world's smallest transistors.The Intel Atom processor is based on an entirely new design, built for low power and designed specifically for a new wave of Mobile Internet Devices and simple, low-cost PC's. This small wonder is a fundamental new shift in design, small yet powerful enough to enable a big Internet experience on these new devices. We believe it will unleash new innovation across the industry." These are the words of Intel Executive Vice President Sean Maloney about their small wonder and latest processor the Atom. The trend toward ever smaller and cheaper PC components is, of course, nothing new. Chips have shrunk and prices have fallen for over 30 years now. Yet that trend has accelerated dramatically in recent years, spurred onward by the rise of mobile computing and signified by the success of low-cost laptops like the Asus Eee PC and high-zoot mobile computers like the iPhone. Sensing this trend, the world's largest chipmaker kicked off an effort four years ago to develop a CPU that could fit inside the power, heat, and size requirements of such devices while maintaining compatibility with its existing lineup of PC processors. Internally at Intel, this processor became known as Silverthorne, and the core logic associated with it was code-named Poulsbo. Together, they make up the so-called Menlow platform. The Silverthorne later was named Atom.
1.2. Interesting and Surprising Choices:
Atom CPUs are surprising for more than one reason: they have modern functions (EM64T, SSSE3, etc.) grafted onto an older architecture The Atom is the first in-order x86 since the Pentium. Power management and fabrication costs are the two imperatives Intel seems to have been guided by, at the expense (with no attempt made to hide it) of performance. So, no, donâ„¢t expect a competitor to Core 2 Duo. But what does the Atom really have to offer? Weâ„¢ll see that as this piece unfolds.
2. SILVERTHORNE
On March 2, 2008, Intel announced the new processor ,code-named Silverthorne, to be used in ultra-mobile PCs/Mobile Internet Devices (MIDs) which will supersede Intel A100. The processor is a 47 million transistor, 25 mm2, sub-3W IA processor which allows2500 chips to fit on a single 300 mm diameter wafer, allowing for extremely economical production. A 1.8 GHz Atom processor's single thread performance is equivalent to its predecessor Intel A100 but should outperform it on applications that can leverage simultaneous multithreading, SSE3, and EM64T x64 extensions.[13] It has a 0.6W to 2.5 TDP rating that can dip down to .01W[14] when idle but that does not include the power consumption of the chipset. It features a 2-issue simultaneous multithreading, 16 stage in- order pipeline with 32KB iL1 and 24KB dL1 caches, integer and floating point execution units, x86 front end, a 512KB L2 cache and a 533MT/s front-side bus. The design is manufactured in 9M 45nm High-k metal-gate CMOS and housed in a 441-ball µFCBGA package Intel designed Silverthorne to fit into thermal and physical footprints that none of its current processors could. In its initial incarnation, Silverthorne will consume between half a watt and two-and-a-half watts, much less than most x86-compatible processors.
3 HISTORY
3.1. Intel and Declining Power Consumption
Power consumptionand integrating a processor into portable or embedded devices have always caused problems for Intel, and this is not the first time the company has offered processors aimed at those uses. But the Atom is radically different in that it has a new architecture specially created to reduce power use. A Short History: Before the Pentium-As far back as the 80386, Intel offered versions intended for low power and especially mobile use. The 80386EX, for example, had a chipset built into the CPU and consumed significantly less power than standard 386s. And low-power versions of the 486, the Pentium, and the Pentium II (the Dixon, with its 256 kB of built-in cache) were also offered. And yet in every case they essentially used a very similar (if not identical) architecture to the one used in the desktop version of the processor. In practice, these processors were efficient, but the difference between a standard version and a version for portable PCs remained slight.
3.2. Pentium-M:
Released in 2003, the Pentium-M was revolutionary in that it used a different architecture from that of the Pentium 4 and consumed much less power, while maintaining high performance. Yet it was still a derivative of the Pentium III, with the same faults, and the successive improvements to the Pentium-M (leading up to the Core 2 processors) have only increased power consumption. Intel has tried to come out with low-power processors (the A1x0, for example), but essentially they were slowed-down versions of the Pentium-M.
3.3. Intel Atom changes all that..
Atom is a different architecture in the sense that it was designed to reduce power consumption and that the processor uses a totally new design. It isn™t an adaptation of an earlier architecture. Concretely, Intel is now able to offer processors that consume very little power “ the high-end Atoms consume less power than the (generally very slow) ULV versions of the standard architectures.
4. THE ATOM Z500 SERIES
The first generation of Atoms is the Z5x0, previously known by the code name Silverthorne. The AtomZ500s are dedicated to MIDs (the famous Mobile Internet Devices) and are coupled to a new chipset, the PoulsboSCH (System Controller Hub).
4.1. Atom vs ARM:
With the MID orientation, it™s clear to see who Intel™s target is “ ARM processors. This very popular architecture (it™s used in the great majority of telephones, PDAs, and GPS devices) is offered by many manufacturers (ARM licenses its instruction set) and offers good performance while keeping power consumption low. In the mobility arena, except for a few rare devices using MIPS architecture (the PSP, for example), ARM processors are in the majority. Intel, incidentally, once produced ARM CPUs for consumer applications and still has a line of products used, for example in RAID cards (the IOP333, for example). In practice, moving from an ARM architecture to x86 poses no real problems “ Linux is obviously compatible, as are Windows CE (used in many GPSs) and the Windows Mobile OS layer (at least in the older versions). In addition, the x86 can also make use of the latest Windows versions and so benefit from broader software (and technical) support than with ARM CPUs.
4.2. The Z500 Processor:
Before we analyze the architecture of the Atom, letâ„¢s look at the Z500 series. These processors are very small, delivered in a package only 13 x 14 mm. The processors are made up of approximately 47 million transistors (more than the original Pentium 4) and have 56 kB of Level-1 cache (24 kB for data and 32 kB for instructions) and 512 kB of Level-2 cache. They operate on a standard Intel bus, the same one used since the Pentium 4. The frequency of the bus is 400 MHz (QDR) or 533 MHz (QDR). There is also support for SIMD instructions, from MMX to SSSE3, EIST, and HyperThreading (making its comeback). Note that the latter technology is available only on certain models (with the 533 MHz QDR bus).
4.3. Poulsbo, A Chipset for the Atom
The SCH (System Controller Hub) is a chipset that includes the Northbridge and Southbridge in the same chip. Dedicated to Atom processors, it is the only one compatible with certain functions such as using the bus in CMOS mode (we™ll talk about that later). The SCH is complete “ it includes a GMA graphics circuit (based on a PowerVR architecture), an HD Audio circuit (simplified, capable of operating only in two channels), a P-ATA controller (Ultra DMA 5, 100 MB/s), and supports two PCI- Express lanes (for a Wi-Ficard, for example). There are also three SDIO/MMC controllers and support for 8 USB ports (with the possibility of using one in client mode). The choice of P-ATA is logical: The controllers used in flash memory are often in this format (used by Compact Flash cards). Three SD controllers might seem strange, but certain types of memory use that connectivity (OneNAND, for example). Also, the DDR2controller of the SCH supports memory with a voltage of 1.5 V (as opposed to 1.8 V for the JEDEC specifications). This little detail is a way of further reducing power consumption.
4.4. The Graphics End of Poulsbo:
On the graphics side thereâ„¢s a new GMA, the GMA 500. It uses a unified architecture and supports 3.0+ Shaders. An interesting point is that it has hardware support for decoding of the H.264, MPEG2, MPEG4, VC1, and WMV9 formats. The frequency of the GMA 500 is 200 MHz or 100 MHz, depending on the chipset version, and itâ„¢s DirectX 10 compatible (not really useful, but worth mentioning), even though the drivers only support DirectX 9. Note that the graphics end is not of Intel origin, but uses a PowerVR technology, unlike other GMA models.
4.5. An Interesting TDP (Thermal Power Design) :
The Atom Z500 has a TDP that varies between 0.85 W (for the 800 MHz version without HyperThreading) and 2.64 W (for the 1.86 GHz model with HyperThreading enabled). The SCH consumes approximately 2.3 W in its most evolved version, which brings the SCH + CPU together to under 5 W. By comparison with existing solutions, that™s obviously a big step forward “ the Via Nano, for example, is announced at 25 W for the 1.8 GHz version and a Celeron-M ULV at 5 W at 900 MHz.
5. ATOM N200 & i945
For Atoms intended for standard PCs, Intelwill offer another line of processors (Diamondville). The Atoms of the N200 and 200 series are meant for standard PCs, but more specifically low-cost portable PCs, like the Eee PCand its competitors.
5.1. Atom N200 and 200
The Atom N200s are similar to the Atom Z500, with the only differences being in the management of EMT64 (64 bits), present in the N200 and 200 models, and the absence of EIST. The Atom 200s, then, donâ„¢t change frequency on the fly. The prices are attractive: An Atom N270, with a frequency of 1.6 GHz (533 MHz bus) and a 2-W TDP costs barely $44. And the 230 version, with a 4-W TDP, costs a mere $29 (at the same frequency).
5.2. A Veteran Chipset , The i945:
The main problem with the Atom N200 stems from the chipset: Intel offers only variants of the i945. This chipset, already old (it dates from 2005), has a major fault: It consumes a lot of power (22 W in the GC version). The i945 chipset supports modern technologies: SATA (2), PCI-Express (1 lane via the ICH7), HD Audio, etc. Obviously it can handle DDR2memory (on two channels) and includes an IGP, the GMA 950. Still, it™s obvious that using an older chipset (from the Napaplatform) with a TDP that™s ten times higher than the processor™s is not the best idea in the world. But it™ll have to do until something better comes along. Portable PCs use the i945GSE, which uses only 5.5 W (4 W for the Northbridge and 1.5 W for the Southbridge). Obviously, the performance is not the same “ in 3D, essentially, where Intel has reduced the GMA™s frequency (from 400 to 133 MHz).
6. THE ATOM ARCHITECTURE
6.1. Atom: In-Order and HyperThreading
The Atom uses a new architecture, but with older technologies. Itâ„¢s the first in-order x86 from Intel since the Pentium, back in 1993. All other Intel processors (since the P6) use an out-of-order architecture. In-Order: Say what
To simplify, think of the processor as receiving the instructions one by one and putting them in its pipeline before executing them. In an in-order architecture, the instructions are executed in the order in which they arrive, whereas an out-of-order architecture is capable of changing the order in the pipeline. The advantage is that losses can be limited. If, for example, you have a simple calculation instruction, a memory access, then another simple calculation, an in-order architecture will execute the three operations one after the other, whereas in OoO the processor can execute the two calculations at the same time and then the memory access, with an obvious time saving. Quite surprisingly, whereas in- order architectures generally use a short pipeline, the Atom has a 16-stage pipeline, which can be a disadvantage in certain cases.
HyperThreading
Is a technology that appeared with the Pentium 4. It can process two threads simultaneously using the unused parts of the pipeline. While not as efficient as two true cores, the technology can make the OS think that the CPU can process two threads simultaneously and increase the computerâ„¢s overall performance. On the Atom with its long pipeline coupled to an in-order architecture, HyperThreading is very effective, and the technology can significantly increase performance without impacting the TDP. Intel claims an increase in consumption of only 10%. 6.2.Processingcore For the rest, the Atom is equipped with two ALUs (units capable of performing integer calculations) and two FPUs (units dedicated to floating-point calculation and very important for gaming, for example). The first ALU manages shift operations, and the second jumps. All multiplicationand addition operations, even in integers, are automatically sent to the FPUs. The first FPU is simple and limited to addition, while the second manages SIMD and multiply/divide operations. Note that the first branch is used in conjunction with the second for 128-bit calculation (the two branches are in 64 bits).
7. OPTIMIZED BASIC INSTRUCTIONS
Intel Atom implements the x86(IA-32) instruction set.If you look at the number of cycles necessary to execute instructions, you realize something: Some instructions are fast and others are (very) slow. A mov or an add, for example, is executed in one cycle, as on a Core 2 Duo, whereas a multiplication (imul) will take five cycles, compared to only three on the Core architecture. Worse, a floating-point division in 32 bits, for example, takes 31 cycles compared to only 17 (or almost half as many) on a Core 2 Duo. In practice “ and Intel willingly admits this “ the Atom is optimized to execute the basic instructions quickly, meaning that this processor short-changes performance with complex instructions. This can be checked simply using Everest (for example), which includes a tool for measuring the latencies of instructions. Fig 7. Operations profile: 96% of all instructions are single Operations in Atom As you may know, Intel calls x86 instructions macro-ops and internal CPU core instructions micro-ops. Like other recent Intel chips, Silverthorne has the ability to fuse multiple macro-ops into a single micro-op. On Silverthorne, basic x86 instructions with
memory operands translate as a single micro-op, which brings higher efficiencies for both decoding and scheduling. The graph above illustrates how Silverthorne handles some typical workloads. Complex x86 instructions like cosine are still micro-coded, but otherwise, an average of 96% of macro-ops execute as directly translated (1:1) or fused single micro-ops. This behavior obviously gives the processor a higher IPC, and Tyler claimed issuing "big chunks" like this increases power efficiency, as well.
8. CACHES
Intel has chosen a fairly out-of-the-ordinary organization for the Atom, but without sacrificing performance (which is important with a CPU using an in-order architecture). 8.1. 24 kB + 32 kB: An Asymmetrical Level 1, Cache The Atom™s Level-1 cache is 56 kB total: 24 kB for data and 32 kB for instructions. This asymmetry, fairly surprising for Intel, stems from the structure of the cache. Intel uses 8 transistors to store one bit, compared to six transistors in a standard cache. This technique allows the voltage applied to the cache to maintain information to be reduced. 8.2. 512 kB Level 2, shrinkable Cache The Level-2 cache has a capacity of 512 kB, and obviously runs at the same frequency as the processor. This 8-way cache is fairly classic and is close in performance to the one used in the Core 2 Duo (its latency is 16 cycles, compared to 14 for the Core 2). One of the new functions can deactivate part of the cache automatically “ if a program doesn™t require much cache memory, part of it can be shut down. In practice, the cache goes from 8-way to 2-way (thus from 512 kB to 128 usable kB). This technique is a way of shaving a few precious milliwatts.
9. POWER CONSUMPTION
Power consumption is central to this Intel platform, and theyâ„¢ve made a lot of efforts in that department. Aside from the chipset, which consumes a lot of power in comparison to the processor, the Atom itself has many attractive functions.
9.1. Bus and cache
As weâ„¢ve already said, Intel has put a lot of effort into the bus and the cache: A different mode for the bus was developed (CMOS mode) and the cache can be disabled in part depending on how itâ„¢s being used. These functions reduce power consumption, as do the use of an in-order architecture and 8T SRAM for the L1 cache C6 power state
In addition to the low voltage (1.05 V) CPU, the Atom also introduces a new standby mode, C6. As a reminder, the C modes (0 to 6) are low-power states, and the higher the number, the less the CPU consumes. In C6 mode, the entire processor is almost totally disabled. Only a cache memory of a few kB (10.5) is kept enabled to store the state of the registers. In this mode, the L2 cache is emptied and disabled, the supply voltage falls to only 0.3 V, and only a small part of the processor remains active, for wake-up purposes. The processor can go into C6 mode in approximately 100 microseconds, which is quick. In practice, Intel claims, C6 mode is used 90% of the time, which limits overall power consumption (obviously, if you launch a program that requires a lot of CPU power or even watch a Flash videoyou wonâ„¢t be in that mode).
10. THE PROS AND CONS
Pros
Low price “ suitable for low-cost PC™s and Mobile Internet Devices (MID™s). Low Power consumption
(lowest in the business).
Low Thermal Design Power(TDP):Low Thermal Design Power enables thinner, lighter, portable netbook devices as it reduces the cooling requirements.
Power-optimized front side bus. Minimizes power needed to transmit data to the processor, resulting in significant power savings and enabling longer battery life - all without impacting performance.
Intel Enhanced deeper sleep(ie the C6 mode).
Hyper threading, a good feature on this processor.
Heavy pipelining.
Atom offers real internet experience with Flash video,Youtube etc in MIDâ„¢s.
Options to include Wi-Fi,Wi-Max,Bluetooth etc.
Cons
The Chipsets
Poor 3D performances
A mismatched platform: the Menlow platform is a little too large, too power-hungry, and too PC-centric to really deliver on Silverthorne's potential.. Once Silverthorne-derived Moorestown system-on-a-
chip arrives, then we'll see the really sweet devices based on this processor technology
come out of the woodwork.Moorestown is the Intel Corporation's code name for
successor to the Menlow platform designed for mobile Internet devices. Current
proposals call for it to use 10 times less power than Silverthorne and to hit the market in
2009-2010.
10. LATEST
The Lenovoâ„¢s Ideapad U8 MID which uses Intelâ„¢s Atom processor have been launched and is destined to be a hit. the mobile internet device has received an official debut at the Beijing Olympics. Weighing just 10.6-ounce, the all-in-one device is powered by an 800MHz Z500 processor, and employs 1GB of RAM (up to 2GB supported), 6 GB SSD as well as dual cameras. Possessing an ability to deliver 5-hour battery life, the mobile internet device enables users to access mobile TV, 802.11b/g wi-fi, Bluetooth, GPS, and EDGE for a superb connectivity to the hilt. Before we forget, the U8 also incorporates a 3G network support and WiMAX Internet access. Measuring 21 x 174 x 84mm and weighing 350g, the latest Lenovo IdeaPad U8 is compatible with China Multimedia Mobile Broadcasting (CMMB) digital television through the USB dongle that enables users to take advantage of free, live coverage of the Olympic Games and also receive other broadcast signals. Lenovo will release the IdeaPad U8 mobile internet device in near future. However, the pricing and availability details are yet to be announced. Features:
4.8Touchscreen.
Bulls eye optical mouse.,for (supposedly) one-handed operation while surfing the web.
A USB slot and a stylus.
1GB RAM.
6GB SSD (Solid State Memory).
Connectivity options like Wi-Fi, bluetooth, GPS, along with EDGE, 3G and WiMAX.
Uses the Intelâ„¢s Atom processor and therefore power efficient,and low in cost(most probably). 25
12. CONCLUSION
If one cares at all about the sort of low-cost and low-power computing devices that Atom targets, it's hard to not be excited about seeing Intel enter this market. The incumbent devices in these markets are too slow, too hot and power-hungry, too expensive, too proprietary, or some combination of those things. It doesn't have to be that way, and Atomâ„¢s interesting new design points the way to a better day, when mobile computing becomes ubiquitous and offers a truly satisfying user experience. Intel's considerable resources in chip design, technology, and manufacturing should help make that day arrive sooner rather than later.
14. REFERENCES
Websites
1.techreport.com
http://techreportarticles.x/14458/1
2.tomshardware.com
http://tomshardwarereviews/intel-atom-cpu,1947.html
3. intel.com
http://inteltechnology/atom/index.htm
4.wikipedia.com
http://en.wikipediawiki/Silverthorne_(CPU)
5.techgadjets.in
http://techgadgetshandhelds/2008/20/lenovo-ideapad-u8-mobile-internet-
device-launched
