Apple's iPad 2 Review: Tom's Goes Down The Tablet Rabbit Hole

GPU Performance: More is Better

Apple's A5 effectively underwent a three-part upgrade. Aside from its processor and memory, the iPad 2 now sports Imagination Technologies’ dual-core PowerVR SGX 543MP2. In comparison, the original iPad employs a single-core PowerVR SGX 535. That's the same GPU Intel used on its GMA 500, built into the Poulsbo series of System Controller Hubs for Atom.

PowerVR SGX 535PowerVR SGX 535

PowerVR SGX 543PowerVR SGX 543

GPU System-on-Chip
PowerVR SGX 535
(Apple A4)
PowerVR SGX 543
(Apple A5)
SIMD
USSE
USSE2
Pipelines
2
4
TMUs
2
2
Bus Width (in bits)
64
64
Triangle rate @ 200 MHz
14 MTriangles/s35 MTriangles/s


The SGX 543 includes four USSE2 (Universal Scalable Shader Engine 2.0) pipes. The SGX 535 only has two USSE pipes. This unified shader design is similar to what we've seen from competing graphics vendors for years, as it allows vertex and pixel shader code to share the same hardware. The idea is to get better performance, even if you’re rendering more of one type of shader. It’s not clear how these are second-generation shaders aside from their name, but Imagination Technologies states that the pipeline effectively delivers “twice the peak floating point and instruction throughput of the Series5 USSE.”

This isn't just about a revised SIMD architecture though. Apple also doubles the number of rendering pipelines again by placing two SGX 543 GPU cores on the A5 (the MP2 in its name represents that pair of GPU cores). This helps account for the iPad 2’s quadrupling of available GPU resources.

GLBenchmark 2.0GLBenchmark 2.0

The GPU clock rate remains an unknown, so benchmarks remain the best way to determine effective performance. Unfortunately, it's difficult to measure real-world graphics capabilities in a meaningful way. There's no real equivalent to Fraps, and we're still a ways away from game developers including frame rate counters in their code. That’s why we turning to GLBenchmark 2.0, a synthetic OpenGL ES 2.0 metric that emphasizes texture performance. Think of it as the 3DMark of mobile devices.

GLBenchmark 2.0Apple iPadApple iPad 2Motorola Xoom
Triangle Test (textured), Mtriangles/s8.629.015.3
Triangle Test (textured, fragment lit), Mtriangles/s4.219.98.6


Like on a desktop, graphics rendering on a tablet begins with an application sending a GPU an array of vertices, vertex shaders, fragment shaders, and a bunch of other control information. The sum of this information is used to draw millions (or billions) of triangles that are used to assemble a larger 3D object. It's important to know the number of triangles that a GPU is capable of rendering because more triangles translates into greater graphics detail. GLBenchmark offers a glimpse into real-world triangle performance because it measures the triangle rate for an actual gaming scene. The results aren't that much of a surprise. At 29.0 Mtriangles/s, the second-generation iPad delivers 3x the performance of its predecessor. This means that game developers can conceivable increase geometric detail three-fold on the iPad 2 and get the same performance out of the original iPad.

The fragment lit test taxes texturing performance, with an additional focus on lighting. Thus, it's a more stressful benchmark. As the geometry becomes more complex, the iPad 2 demonstrates its improved handling of more detailed graphics workloads. It actually delivers about five times more performance than the original iPad.

GLBenchmark 2.0
Frames per set duration
Apple iPadApple iPad 2Motorola Xoom
Egypt frames (frames)
575
5075
1371
Pro (frames)
880
2897
1347


The performance of an actual graphics scene is easier to understand. When you look at this in terms of frames rendered in a set period of time, you're getting a lot more performance with the iPad 2. Conservatively, you're looking at least 3x more frames rendered according to the Pro test, and up to 8x more according to the Egypt test.

Comparing GPU Performance: Words of Caution

If you really want to go to the trouble of researching tablet-based graphics performance (there may be a few of you out there), bear in mind that potential won't always match up to the numbers you see in the real world. The form factor's constraints prevent vendors from pairing graphics hardware with the memory that'd best demonstrate its peak specifications, for example. Instead, you end up with the configuration that hits the performance profile needed, and nothing more. 

On the desktop, a graphics card manufacturer has the freedom to balance performance between a GPU and its memory subsystem, altering data rate, memory bus width, and capacity to best exploit the processor's capabilities, whether they're bleeding-edge or decidedly mainstream. When you're dealing with smartphones and tablets, that's no longer the case. In order to cut back on power, minimize heat, or avoid monopolizing too much space on the PCB, engineers might tolerate a memory bottleneck in order to achieve other design goals. So, forget comparing individual and theoretical pieces of the graphics puzzle. Rather, focus on the end product's measurable performance.

GLBenchmark 2.0Apple iPadApple iPad 2Motorola Xoom
Egypt with FSAA (frames)
436
5057
-
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/s170980918551129897
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/s3774111653003
Exponential Test (balanced) kshader/s2043117351656
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/s6045225573211
Branching Test (balanced) kshader/s2106111931493
Array Test (uniform array access) kvertex/s291836583946
Triangle Test (white) ktriangle/s95482995712595
Triangle Test (textured, vertex lit) ktriangle/s70582112910520
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63 comments
    Your comment
  • Yuka
    What about adding other tablets in the mix?

    The XOOM could be a good choice, or the Asus Transformer.

    Cheers!
    3
  • acku
    We'll get to the others soon enough, but it's difficult to talk about other tablets without talking about Apple products.

    Cheers,
    Andrew Ku
    TomsHardware.com
    7
  • Nintendork
    Samsung Galaxy 10.1 anyday.
    0
  • gidgiddonihah
    Here is the article where all the Apple fanboys start to tear this article up :).
    -6
  • gidgiddonihah
    Oops, sorry for the poor grammer :). Posted without rereading...

    Here is an article that Apple fanboys would be glad to rip up.
    3
  • Tijok
    gidgiddonihahHere is the article where all the Apple fanboys start to tear up .


    Fixed it for you. ;)
    2
  • Benihana
    Still no HDD expandability? No thanks. I'm not rich.
    1
  • Anonymous
    Disagree.
    Like most computer guys like myself, adding an ipad won't make us to pack our PC/Mac to our closet. But again, mistakes like Microsoft or Linux, the "most computer guys on earth" are actually just a small group in total.
    For example:
    i've been teaching my 80 years old grandma to use pc to download, install and play simple games for years, no success. then she learned how to find/download/install/play many games after few days playing with my ipad.
    my 5 years nephew reads/plays/watch cartoons all on ipad now, she didn't turn on her pc for weeks.
    For myself, i uninstalled all my online video, movie client applications from my laptop, as I found watching these on ipad is much comfortable.

    Yes I still do my works on my pc, mostly in my office. At home, now the only thing force me to turn on my pc is to play world of warcraft
    I mean, who says ipad can't replace anything?
    2
  • acku
    joeyluDisagree.Like most computer guys like myself, adding an ipad won't make us to pack our PC/Mac to our closet. But again, mistakes like Microsoft or Linux, the "most computer guys on earth" are actually just a small group in total.For example:i've been teaching my 80 years old grandma to use pc to download, install and play simple games for years, no success. then she learned how to find/download/install/play many games after few days playing with my ipad.my 5 years nephew reads/plays/watch cartoons all on ipad now, she didn't turn on her pc for weeks.For myself, i uninstalled all my online video, movie client applications from my laptop, as I found watching these on ipad is much comfortable. Yes I still do my works on my pc, mostly in my office. At home, now the only thing force me to turn on my pc is to play world of warcraftI mean, who says ipad can't replace anything?


    I'd actually argue that in your case you're not replacing a PC, you're augmenting it. Granted, there will be others like your nephew and grandmother who can use an iPad as their primary device.
    3
  • damianrobertjones
    May I simply say, "thank you" to Toms for writing a well thought out objective, honest and practical review of thr iPad2. Instead of getting carried away you've hit the nail on the head.

    P.s. I use an Acer W500 and I still struggle to justify why i have it.
    8
  • Maziar
    Good too see you guys are writing about tablets.Hope this trend continues and we can see reviews of more tablets :)
    5
  • Marcus52
    In my opinion, the tablet is a fad that will go away when everyone finds out they are very cool looking toys that really don't add anything to what you can do.

    Oh, don't get me wrong; I think they'll make their permanent mark on the smart phone and laptop scenes, the devices that really fit into people's lives - but the tablet is too limited and too clumsy in actual use.

    Certainly, they have their niche uses - as book readers, like the Kindle, for example, but as something that will actually replace anything, I think not. Lots of coolz, little practicality.

    ;)
    2
  • VVV850
    What about light bleeding? I mean, the number of Ipads 2 that have this issue is staggering and has to be included in a review
    2
  • molo9000
    Marcus52In my opinion, the tablet is a fad that will go away when everyone finds out they are very cool looking toys that really don't add anything to what you can do.Oh, don't get me wrong; I think they'll make their permanent mark on the smart phone and laptop scenes, the devices that really fit into people's lives - but the tablet is too limited and too clumsy in actual use.Certainly, they have their niche uses - as book readers, like the Kindle, for example, but as something that will actually replace anything, I think not. Lots of coolz, little practicality.

    They don't "add anything to what you can do", but they do certain things much better than other devices.

    Reading this article on my iPad while sitting on a sofa was certainly much more comfortable than reading it on my desktop or laptop.
    2
  • phraun
    molo9000They don't "add anything to what you can do", but they do certain things much better than other devices.Reading this article on my iPad while sitting on a sofa was certainly much more comfortable than reading it on my desktop or laptop.


    You need a more comfortable computer chair. =)
    0
  • damianrobertjones
    Reading this article on a 108" projector screen was a lot more comfortable... :)
    4
  • altoidman85
    molo9000They don't "add anything to what you can do", but they do certain things much better than other devices.Reading this article on my iPad while sitting on a sofa was certainly much more comfortable than reading it on my desktop or laptop.


    You should have taken the money you spent on your ipad and bought a more comfortable desk and chair for your desktop. Then a few cases of beer.
    -1
  • brendonmc
    Spot on. Even Microsoft recognized that Windows Mobile applications had to be compatible with the full versions. Unfortunately there just wasn't the hardware to make it run....well....
    Oh, and using a stylus to type sucks.
    1
  • jdamon113
    This is Boring, just like a tablet.
    -4
  • Anonymous
    I only justify having a tablet for my girlfriend, who's work place (Hospital ER) will not allow laptop use during her down time, to browse or chat w/ me. But they do allow them to read books, or e-readers, so she has a nook color running Cyanogenmod7, so i guess the onl ytime a tablet is useful to us is when a laptop strictly isnt allowed.
    2