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Tegra 2: Nvidia Goes Mobile

Motorola Xoom: The First Android 3.1 (Honeycomb) Tablet
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As we’ve mentioned in the past, mobile devices like smartphones and tablets use what’s known as a system-on-chip (SoC). This integrates the processor, GPU, RAM, along with several other subsystems onto single device. Since all of those components sit next to each other on the same chip, there is greater efficiency in data transfers, while reducing the amount of space consumed on the PCB.


Apple A4 (iPad)
Apple A5 (iPad 2)
Tegra 2 (Xoom)
Processor
1 GHz ARM Cortex-A8 (single-core)
1 GHz ARM Cortex-A9 (dual-core)
1 GHz ARM Cortex-A9 (dual-core)
Memory
256 MB 333 MHz LP-DDR (single-channel)
512 MB 800 MHz LP-DDR2 (dual-channel)
1 GB 667 MHz LP-DDR2 (single-channel)
Graphics
PowerVR SGX535
PowerVR SGX545MP2
ULP GeForce
L1 Cache
(Instruction/Data)
32 KB / 32 KB32 KB / 32 KB32 KB / 32 KB
L2 Cache640 KB1 MB1 MB


Tegra is Nvidia’s SoC brand, and it symbolizes the company’s effort to tap into the mobile market beyond its desktop-derived GeForce graphics processors. A lot of engineering is tied up in this initiative, and what we see today in tablets like the Xoom represents the company's second incarnation of Tegra.

You may be asking "What happened to the first Tegra?" Flatly, it was far less impressive, even when it hit the market in 2009. Compared to Apple’s A4, it was a much more conservative design. Nvidia choose the older ARM11 processor, which probably explains the lack of design wins. Microsoft’s Zune HD was the only major product that employed the original Tegra.

Tegra 2Tegra 2

Tegra 2 is an entirely different beast. It’s based on the Cortex-A9, which is a generation ahead of the older ARM11. This is the same CPU seen in Apple’s A5 (iPad 2). Read Apple's iPad 2 Review: Tom's Goes Down The Tablet Rabbit Hole for a full discussion of Cortex-A9 performance.

Tegra 2: Graphics Processing PipelineTegra 2: Graphics Processing Pipeline

The ultra-low power GeForce isn't just a physically smaller GPU than the A5’s SGX 543MP2. Unlike Nvidia's desktop GPUs, Tegra 2 is based on an architecture that pre-dates its unified design. So, you’re looking at four pixel shader cores and four vertex shader cores. This means Tegra 2 operates most efficiently when it's presented with an even mix of vertex and shader code. We expect Nvidia to address that constraint in Tegra 3 (code named Kal-El).

GPU (System-on-Chip)
PowerVR SGX 535
(Apple A4)
PowerVR SGX 543
(Apple A5)
ULP GeForce (Tegra 2)
SIMD
USSE
USSE2
Core
Pipelines
2 (unified)
4 (unified)
8 (4 pixel / 4 vertex)
TMUs
2
2
2
Bus Width (bit)
64
64
32
Triangle rate @ 200 MHz
14 MTriangles/s35 MTriangles/s?


The ULP GeForce has a maximum operating frequency of 300 MHz, but device vendors can tweak this setting to save on power. Nvidia provides less information on the Tegra 2 than it does for its desktop GPUs, so it’s best to move on to benchmarks. As in our iPad 2 review, we're turning to GLBenchmark 2.0.

In terms of frames rendered in a set period of time, the Xoom offers more performance than the original iPad, but it still falls short of the iPad 2. Conservatively, Google's first Honeycomb-based tablet renders 50% fewer frames according to the Pro test, and up to 3.7x less according to the Egypt test.

GPU (System-on-Chip)
PowerVR SGX 535
(Apple A4)
PowerVR SGX 543
(Apple A5)
ULP GeForce (Tegra 2)
SIMD
USSE
USSE2
Core
Channels
Single
Dual
Single
Memory Bandwidth
2.6 GB/s
17.0 GB/s
2.6 GB/s


You can't use fill or triangle rates to draw a direct comparison of how well Tegra 2 utilizes its memory bandwidth, even though it's a quick-and-dirty way of sizing up other mobile GPUs.

According to Intel, the SGX 535 (GMA 500) requires 4.2 GB/s of memory bandwidth to reach a 14 Mtriangles/s triangle rate, but that's not the result that we get in GLBenchmark's triangle test. If you do the math, you'll find that the iPad's A4 uses 333 MHz LP-DDR, which offers up to 2.6 GB/s of throughput. This matches the memory bandwidth ratio (2.6/4.2 = 63%) to the triangle rate (8.6/14 = 61%).

In comparison, the iPad 2 uses 800 MHz LP-DDR2 in a dual-channel configuration. This adds up to about 17.0 GB/s of memory bandwidth. GLBenchmark suggests that this isn't enough though, because a single-core SGX 543 should reach 35 Mtriangles/sec. And yet, we only achieve about 30 Mtriangles/sec with our dual-core SGX 543. Adding another core doesn't exactly double performance because it's not a linear scale. However, given our previous experience with desktop GPUs, we suspect that another 30-40% could be squeezed out of the iPad 2's GPU if Apple used higher-performance memory.

We can make this assertion because there is a direct relationship between memory bandwidth and triangle rates in the A4's and A5's PowerVR GPUs, due to their tile-based deferred rendering architecture. Those GPUs operate differently than what we're used to seeing on the desktop. Tegra 2, however, is an entirely different beast. It employs a more traditional z-buffered rendering architecture, like desktop GPUs. That's why it's pointless to compare triangle and fill rates. It's more important to look at the Egypt and Pro benchmarks.

Interestingly, Tegra 2 only employs a single-channel 32-bit LP-DDR2 memory controller. This could be a bottleneck restricting performance, but there is no benchmark we can use to determine that for sure. Then again, we do know that the version of Tegra 2 in the Xoom is somewhat restricted. Motorola wanted to emphasize better battery life, so it capped the Tegra 2's memory clock at 600 MHz. This effectively limits bandwidth to 2.4 GB/s. Nvidia specs the Tegra 2 for up to 667 MHz operation, which means there could be other tablets that offer better performance through a higher data rate.

GLBenchmark 2.0Apple iPadApple iPad 2Motorola Xoom
Egypt frames (frames)
575
5075
1371
Egypt with FSAA (frames)
436
5057
-
Pro (frames)
880
2897
1347
Pro with FSAA (frames)
672
2851
-
Egypt with FSAA Fixed Time (sec)
825.6
65.0
-
Pro with FSAA Fixed Time (sec)
123.3
22.6
-
Swap Buffer Test (frames)
600
599
603
Fill Test (texture fetch) ktexel/s17 098091 855112 9897
Trigonometric Test (vertex weighted) kvertex/s103933262632
Trigonometric Test (fragment weighted) kfragment/s119135124452
Trigonometric test (balanced) kshader/s125931582543
Exponential Test (vertex weighted) kvertex/s313035352628
Exponential Test (fragment weighted) kfragment/s377411 1653003
Exponential Test (balanced) kshader/s204311 7351656
Common Test (vertex weighted) kvertex/s152437271973
Common Test (fragment weighted) kfragment/s163436994451
Common Test (balanced) kshader/s106541142530
Geometric Test (Vertex Weighted) kvertex/s194937761316
Geometric Test (Fragment Weighted) kfragment/s208163882888
Geometric Test (Balanced) kshader/s128161811628
For Loop Test (Vertex Weighted) kvertex/s167138601315
For Loop Test (Fragment Weighted) kfragment/s184262377271
For Loop Test (balanced) kshader/s127537183583
Branching Test (vertex weighted) kvertex/s390637782633
Branching Test (fragment weighted) kfragment/s604522 5573211
Branching Test (balanced) kshader/s210611 1931493
Array Test (uniform array access) kvertex/s291836583946
Triangle Test (white) ktriangle/s954829 95712 595
Triangle Test (textured, vertex lit) ktriangle/s705821 12910 520
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  • 4 Hide
    dragonsqrrl , July 8, 2011 5:06 AM
    Very impressive review, especially the display quality page. A lot of in-depth information.
  • 3 Hide
    joytech22 , July 8, 2011 5:34 AM
    Excellent! Covered everything I was interested in when comparing the iPad 2 to the Xoom.
  • 4 Hide
    tramit , July 8, 2011 5:54 AM
    Excellent review. I also agree that the excuse of Android coming later in the game does not mean it cannot have the same growth in apps in the same alotted time frame that it was released.

    I personally feel that the iPad is a better device for gaming just by going through the app store and being able to find games ranging from Monopoly to FF3 and Infinity Blade. I have a Nexus S right now and the list of attractive games is not as long.

    I like having both devices however. I plan to stay the course with continuing to purchase Android Nexus phones and having Apple supply me with their iPad. I get to enjoy the best of both worlds and not narrow my enjoyment of tech like most Droid and Apple fanboys.
  • 3 Hide
    Maziar , July 8, 2011 6:06 AM
    Excellent review.
    I'm impressed with the honeycomb but I think it has 2 major drawbacks
    1)UI is somehow laggy and not 100% smooth
    2)Lack of apps.
    If these 2 issues get fixed,then we're going to see a better competition
  • 1 Hide
    fstrthnu , July 8, 2011 6:06 AM
    A little late, but very good quality review. Very nice to see custom benchmarks, it really shows you guys put in the effort here.

    I'd probably go for a Samsung Galaxy Tab 10.1, but that's just me.
  • 0 Hide
    Anonymous , July 8, 2011 8:40 AM
    Seems HD video playback was not tested. Nice to have a HDMI option, but not really useful if most HD movies cannot play smoothly as is the case with the XOOM.

    Also, and probably related to the slow video, Tegra 2's CPU has no NEON extensions, limiting applications that use signal processing.

    Yes, I do own a XOOM (also iPad 2 by the way)
  • 1 Hide
    acku , July 8, 2011 8:42 AM
    Quote:
    Seems HD video playback was not tested. Nice to have a HDMI option, but not really useful if most HD movies cannot play smoothly as is the case with the XOOM.

    Also, and probably related to the slow video, Tegra 2's CPU has no NEON extensions, limiting applications that use signal processing.

    Yes, I do own a XOOM (also iPad 2 by the way)



    Check out page 13. We tested H.264 battery life using a ripped 1280x720 Blu-ray movie.

    On page 12, we also show HD playblack when you're mirroring the display.

    @Everyone else. Thanks for the comments guys. If there's anything else you guy want to see in future reviews please let us know.

    Cheers,
    Andrew Ku
    TomsHardware.com
  • -2 Hide
    house70 , July 8, 2011 11:40 AM
    Took quite a while to get this review done. Other tablets are already available that sport Honeycomb. Not to mention they are better than both contenders described in this article. I have a Transformer and no matter what I throw at it, it does it well. A review of that would be nice (maybe in another year or so...).
    Good effort, but as others have said, late to the table.
  • -2 Hide
    house70 , July 8, 2011 11:46 AM
    What the reviewer perceives as weaknesses, others perceive as strength. Example: the apps installation process. Not having to deal with iTunes is a bonus in itself, and having the option to make your own backups using whatever application you prefer is also a plus. The reviewer got a bit carried away by his personal bias towards iTunes/iOS environment. There are people that prefer to be led by hand while operating their tablet and there are others that prefer to pick and choose their options without limitations. It's a matter of personal preference. But this should not transpire into an objective review. Other than that, not too bad.
  • -1 Hide
    Anonymous , July 8, 2011 12:08 PM
    Wow - I couldn't disagree more with some of your views. Obviously you love you some Apple... I'm not an Apple hater - I have a Macbook Pro, I have an iPad, and I have a Xoom. I tell everyone the Xoom is 5X the tables the iPad is (Granted it's an iPad, not an iPad2 - but my beef with iPads are how much Apple controls what you can or can't do with it - that has not changed in the new generation of iPads). The iPad I can use as a toy, or as a cool media gadget - I actually basically gave it to my 6 year old son now bc that's all I can do with it. The Xoom I can use as so much more - it is was more useful on so many levels. Yes rendering takes a bit longer when you flip th screen, yes there are a few small quirks in it's behavior occasionally, but from an overall usefulness point of view I like it TONS betters than the iPad. Widgets - MultiTasking - OpenSource app development with an App store NOT controlled by Apple. Android IS the future for tablets. Apple needs to take note - they are just lucky at this point bc of their following, but Android will leave them in the dust. MS isn't even in the game and won't be even when Windows 8 hits. And you price comparison is off too IMO. $599 (now $499) for 32MB on the Xoom was in line (and is now better) than Apple's price point. Take it a step further and look the the Asus Eee Pad Transformer (very similar to Xoom with some things done even better) at $399. Android is taking hold, and will gain on Apple quickly, and eventually blow them away.
  • 4 Hide
    acku , July 8, 2011 12:15 PM
    house70Took quite a while to get this review done. Other tablets are already available that sport Honeycomb. Not to mention they are better than both contenders described in this article. I have a Transformer and no matter what I throw at it, it does it well. A review of that would be nice (maybe in another year or so...).Good effort, but as others have said, late to the table.


    I'll take that shot. Understand that we just started in with tablets. So we're playing catch up, but we're not purposely reviewing tablets late.

    That said, I don't think it's necessary to be snarky about it.

    Quote:
    What the reviewer perceives as weaknesses, others perceive as strength. Example: the apps installation process. Not having to deal with iTunes is a bonus in itself, and having the option to make your own backups using whatever application you prefer is also a plus. The reviewer got a bit carried away by his personal bias towards iTunes/iOS environment. There are people that prefer to be led by hand while operating their tablet and there are others that prefer to pick and choose their options without limitations. It's a matter of personal preference. But this should not transpire into an objective review. Other than that, not too bad.


    I'll agree that we can disagree. But I don't think that makes my concerns any less valid. And it's true that many people don't care for that hand holding experience, but again, that is why I called the iPad a Wii and the Xoom a PS3.

    I'm speaking from experience as an Android AND iOS developer. The hoops that you have to jump through for the Apple App store are infuriating. But if you're a tablet user, you don't care that said developer had to wrack his brain dealing with Apple. You just want to know apps are available. No tablet platform can truly succeed without third-party application support. This is a reality that everyone has to face. It's also a reason that Apple still struggles in the notebook and desktop market with OS X. There are more programs for Windows that you can't run on Mac. Until this changes, the playing field is going to be uneven.

  • 5 Hide
    acku , July 8, 2011 12:21 PM
    WebologyWORXWow - I couldn't disagree more with some of your views. Obviously you love you some Apple... I'm not an Apple hater - I have a Macbook Pro, I have an iPad, and I have a Xoom. I tell everyone the Xoom is 5X the tables the iPad is (Granted it's an iPad, not an iPad2 - but my beef with iPads are how much Apple controls what you can or can't do with it - that has not changed in the new generation of iPads). The iPad I can use as a toy, or as a cool media gadget - I actually basically gave it to my 6 year old son now bc that's all I can do with it. The Xoom I can use as so much more - it is was more useful on so many levels. Yes rendering takes a bit longer when you flip th screen, yes there are a few small quirks in it's behavior occasionally, but from an overall usefulness point of view I like it TONS betters than the iPad. Widgets - MultiTasking - OpenSource app development with an App store NOT controlled by Apple. Android IS the future for tablets. Apple needs to take note - they are just lucky at this point bc of their following, but Android will leave them in the dust. MS isn't even in the game and won't be even when Windows 8 hits. And you price comparison is off too IMO. $599 (now $499) for 32MB on the Xoom was in line (and is now better) than Apple's price point. Take it a step further and look the the Asus Eee Pad Transformer (very similar to Xoom with some things done even better) at $399. Android is taking hold, and will gain on Apple quickly, and eventually blow them away.


    Everyone who criticizes Apple for some reason feels the need to say they own an Apple product, as if that somehow means something. It doesn't really matter what you own. Anyone can have a valid opinion.

    I understand your view, I just disagree with it. The idea that open source dominates doesn't jive with what every computer user experiences. Look at Linux. If open source was simply the issue, Ubuntu should kill Windows and OS X within the next few years. That's simply not the case.

    I'm an Android and iOS developer. In fact I have to program in both because some of the benchmarks we use are custom coded. As a reader, though, most people could care less how much effort I put into a program. They just want to look at the results. No tablet platform can truly succeed without third-party application support. This is a reality that everyone has to face. It's also a reason that Apple still struggles in the notebook and desktop market with OS X. There are more programs for Windows that you can't run on Mac. Until this changes, the playing field is going to be uneven.


    And on that note, if the Xoom was all that and a bag of chips, Motorola wouldn't admit it's struggling with sales and drop the price.
  • 0 Hide
    Onus , July 8, 2011 1:36 PM
    For the same amount of money, I can get a Brazos-based notebook with superior performance, more applications, a real keyboard, expandability, full interoperability with my PC, and the only thing I'll give up is some battery life (but apparently not all that much); oh, and an extra camera.

    I just don't see a tablet in my future.
  • 0 Hide
    lamorpa , July 8, 2011 1:49 PM
    jtt283For the same amount of money, I can get a Brazos-based notebook with superior performance, more applications, a real keyboard, expandability, full interoperability with my PC, and the only thing I'll give up is some battery life (but apparently not all that much); oh, and an extra camera. I just don't see a tablet in my future.

    You'll also have to give up not having a keyboard and display stand.
  • 1 Hide
    smeker , July 8, 2011 2:45 PM
    jtt283For the same amount of money, I can get a Brazos-based notebook with superior performance, more applications, a real keyboard, expandability, full interoperability with my PC, and the only thing I'll give up is some battery life (but apparently not all that much); oh, and an extra camera. I just don't see a tablet in my future.


    I m really happy for you and for sharing this news which has nothing to do with the article.... Keep up with the great trolling job! :) 
  • -1 Hide
    drchemist , July 8, 2011 2:53 PM
    Galaxy Tab 10.1 was the FIRST tablet with Honeycomb 3.1 by almost 1 month. Change your headline. Google I/O doesn't count since it was a limited test edition for developers. Consumer released version on June 8. Check it.
  • 2 Hide
    acku , July 8, 2011 2:57 PM
    drchemistGalaxy Tab 10.1 was the FIRST tablet with Honeycomb 3.1 by almost 1 month. Change your headline. Google I/O doesn't count since it was a limited test edition for developers. Consumer released version on June 8. Check it.


    Not true at all.
    http://www.engadget.com/2011/05/10/google-announces-android-3-1
    5/10 3.1 was available to Verizon Xoom owners. Xoom was first 3.0 and first 3.1
  • -1 Hide
    winterblade , July 8, 2011 3:16 PM
    Hello guys. A few months ago I really thought tablets were just a gimmick and that, iOS or Android, I would never get one, then I noticed that more and more frequently I rather use my Motoroi (the mexican version of the original Droid) than my laptop (a Dell Studio XPS 13) for simple tasks like chat, light browsing, checking mail and hell even for gaming I found myself using more and more my phone, but I really get tired soon because of the small display... so it soon became a no brainer that I wanted a tablet.

    I could really not say if it´s because I'm waaaaaaaaay more used to use android devices than iOS ones, but seriously, iPad being more intuitive than the Xoom my ass... I love the Android buttons in my phone and I love the software buttons in my Xoom. Of course iPad is going to be more intuitive if you are an iPhone user, is the same frikkin OS. I'm a PC user and as such I can tell you I feel at home with android from day one, iOS and OS X, even when pretty at first sight, are just not enough functional for me and I really find no value in that famous "apple experience" and since mankind is yet to design a experience-o-metter it is my humble opinion that in an OBJECTIVE review it should not be regarded over and over again, maybe in an editorial, but not in a review.

    About people saying they rather get a netbook or even a notebook instead a tablet (I was one of those not long ago) The only thing I can say is that if some one manage to make a 1.5 pound netbook with the 8-9 hours of constant use I can get from my Xoom I will agree with you then, but not today, tablets do have advantages over traditional systems.
  • 1 Hide
    irtehyar , July 8, 2011 3:22 PM
    Good article.

    I'm an android phone owner and an ipad owner, and am slowly being converted to iOS for mobile simply because of the vast amount of applications I use that aren't even similarly available on the Android OS. This is painful for me because I'm a Windows programmer and I despise Apple, assemble my own PCs, etc. I'm pretty typical there I guess. But in the end, I just want something that does what I want (music and language apps, mostly), and when it comes to tablet software, only the iPad delivers for me.

    I wonder if this is similar to the way people in music and education felt in the early days of Mac vs PC, when Apple had the best experience and best apps for certain industries? These days I could never go Mac because it does a very tiny fraction of what I do on the PC. Not the case for the more limited tablet world.
  • 3 Hide
    acku , July 8, 2011 3:25 PM
    winterbladeHello guys. A few months ago I really thought tablets were just a gimmick and that, iOS or Android, I would never get one, then I noticed that more and more frequently I rather use my Motoroi (the mexican version of the original Droid) than my laptop (a Dell Studio XPS 13) for simple tasks like chat, light browsing, checking mail and hell even for gaming I found myself using more and more my phone, but I really get tired soon because of the small display... so it soon became a no brainer that I wanted a tablet.I could really not say if it´s because I'm waaaaaaaaay more used to use android devices than iOS ones, but seriously, iPad being more intuitive than the Xoom my ass... I love the Android buttons in my phone and I love the software buttons in my Xoom. Of course iPad is going to be more intuitive if you are an iPhone user, is the same frikkin OS. I'm a PC user and as such I can tell you I feel at home with android from day one, iOS and OS X, even when pretty at first sight, are just not enough functional for me and I really find no value in that famous "apple experience" and since mankind is yet to design a experience-o-metter it is my humble opinion that in an OBJECTIVE review it should not be regarded over and over again, maybe in an editorial, but not in a review.About people saying they rather get a netbook or even a notebook instead a tablet (I was one of those not long ago) The only thing I can say is that if some one manage to make a 1.5 pound netbook with the 8-9 hours of constant use I can get from my Xoom I will agree with you then, but not today, tablets do have advantages over traditional systems.


    I honestly can't speak from iPhone experience. Other TH coworkers have iPhones, but I don't. I actually have an Android phone, one that I purchased prior to any tablet use.

    Some of what I'm speaking from comes from my experience as an Android and iOS developer. Most of my comments on usability are simply issues with UI. As I stated in the review, the iPad is more analogous to the Wii, whereas Xoom feels more like a PS3. It's really a different experience.

    Quote:
    Good article.

    I'm an android phone owner and an ipad owner, and am slowly being converted to iOS for mobile simply because of the vast amount of applications I use that aren't even similarly available on the Android OS. This is painful for me because I'm a Windows programmer and I despise Apple, assemble my own PCs, etc. I'm pretty typical there I guess. But in the end, I just want something that does what I want (music and language apps, mostly), and when it comes to tablet software, only the iPad delivers for me.

    I wonder if this is similar to the way people in music and education felt in the early days of Mac vs PC, when Apple had the best experience and best apps for certain industries? These days I could never go Mac because it does a very tiny fraction of what I do on the PC. Not the case for the more limited tablet world.



    Thanks for the kudos. As a programmer, you probably understand the problem of third-party app support in a way most people don't.

    On the second sentiment, I'm really not sure how this is going to play out. There are too many variables. So much of this has to do wtih product vision. Apple didn't help itself when it booted out Jobs back in the early days. The Android CTO Steve Horowitz left for Coupons a while back, but there are many talented people at the helm at Google. We probably need another year or two before the fog on the battlefield clears.
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