GPU Performance

All of our discussions around the new iPad and its silicon thus far have been in the theoretical space. Unfortunately the state of Android/iOS benchmarking is abysmal at best today. Convincing game developers to include useful benchmarks and timedemo modes in their games is seemingly impossible without a suitably large check. I have no doubt this will happen eventually, but today we're left with some great games and no way to benchmark them.

Without suitable game benchmarks, we rely on GLBenchmark quite a bit to help us in evaluating mobile GPU performance. Although even the current most stressful GLBenchmark test (Egypt) is a far cry from what modern Android/iOS games look like, it's the best we've got today.

We'll start out with the synthetic tests, which should show us roughly a 2x increase in performance compared to the iPad 2. Remember the PowerVR SGX 543MP4 simply bundles four SGX 543 cores instead of two. Since we're still on a 45nm LP process, GPU clocks haven't increased so we're looking at a pure doubling of virtually all GPU resources.

GLBenchmark 2.1—Fill Test

GLBenchmark 2.1—Triangle Test (White)

GLBenchmark 2.1—Triangle Test (Textured, Fragment Lit)

Indeed we see a roughly 2x increase in triangle and fill rates. Below we have the output from GLBenchmark's low level tests. Pay particular attention to how, at 1024 x 768, performance doubles compared to the iPad 2 but at 2048 x 1536 performance can drop to well below what the iPad 2 was able to deliver at 10 x 7. It's because of this drop in performance at the iPad's native resolution that we won't see many (if any at all), visually taxing games run at anywhere near 2048 x 1536.

GLBenchmark 2.1.3 Low Level Comparison
  iPad 2 (10x7) iPad 3 (10x7) iPad 3 (20x15) ASUS TF Prime
Trigonometric test—vertex weighted
35 fps
60 fps
57 fps
47 fps
Trigonometric test—fragment weighted
7 fps
14 fps
4 fps
20 fps
Trigonometric test—balanced
5 fps
10 fps
2 fps
9 fps
Exponential test—vertex weighted
59 fps
60 fps
60 fps
41 fps
Exponential test—fragment weighted
25 fps
49 fps
13 fps
18 fps
Exponential test—balanced
19 fps
37 fps
8 fps
7 fps
Common test—vertex weighted
49 fps
60 fps
60 fps
35 fps
Common test—fragment weighted
8 fps
16 fps
4 fps
28 fps
Common test—balanced
6 fps
13 fps
2 fps
12 fps
Geometric test—vertex weighted
57 fps
60 fps
60 fps
27 fps
Geometric test—fragment weighted
12 fps
24 fps
6 fps
20 fps
Geometric test—balanced
9 fps
18 fps
4 fps
9 fps
For loop test—vertex weighted
59 fps
60 fps
60 fps
28 fps
For loop test—fragment weighted
30 fps
57 fps
16 fps
42 fps
For loop test—balanced
22 fps
43 fps
11 fps
15 fps
Branching test—vertex weighted
58 fps
60 fps
60 fps
45 fps
Branching test—fragment weighted
58 fps
60 fps
30 fps
46 fps
Branching test—balanced
22 fps
43 fps
16 fps
16 fps
Array test—uniform array access
59 fps
60 fps
60 fps
60 fps
Fill test—Texture Fetch
1001483136 texels/s
1977874688
texels/s
1904501632
texels/s
415164192
texels/s
Triangle test—white
65039568
triangles/s
133523176
triangles/s
85110008
triangles/s
55729532
triangles/s
Triangle test—textured
56129984
triangles/s
116735856
triangles/s
71362616
triangles/s
54023840
triangles/s
Triangle test—textured, vertex lit
45314484
triangles/s
93638456
triangles/s
46841924
triangles/s
28916834
triangles/s
Triangle test—textured, fragment lit
43527292
triangles/s
92831152
triangles/s
39277916
triangles/s
26935792
triangles/s

GLBenchmark also includes two tests designed to be representative of a workload you could see in an actual 3D game. The older Pro test uses OpenGL ES 1.0 while Egypt is an ES 2.0 test. These tests can either run at the device's native resolution with vsync enabled, or rendered offscreen at 1280 x 720 with vsync disabled. The latter offers us a way to compare GPUs without device screen resolution creating unfair advantages.

Unfortunately there was a bug in the iOS version of GLBenchmark 2.1.2 that resulted in all on-screen benchmarks running at 1024 x 768 rather than the new iPad's native 2048 x 1536 resolution. This is why all of the native GLBenchmark scores from the new iPad are capped at 60 fps. It's not because the new GPU is fast enough to render at speeds above 60 fps at 2048 x 1536, it's because the benchmark is actually showing performance at 1024 x 768. Luckily, GLBenchmark 2.1.3 fixes this problem and delivers results at the new iPad's native screen resolution:

GLBenchmark 2.1—Egypt (Standard)

GLBenchmark 2.1—Pro (Standard)

Surprisingly enough, the A5X is actually fast enough to complete these tests at over 50 fps. Perhaps this is more of an indication of how light the Egypt workload has become, as the current crop of Retina Display enhanced 3D titles for the iPad all render offscreen to a non-native resolution due to performance constraints. The bigger takeaway is that with the 543MP4 and a quad-channel LP-DDR2 interface, it is possible to run a 3D game at 2048 x 1536 and deliver playable frame rates. It won't be the prettiest game around, but it's definitely possible.

The offscreen results give us the competitive analysis that we've been looking for. With a ~2x die size advantage, the fact that we're seeing a 2-3x gap in performance here vs. NVIDIA's Tegra 3 isn't surprising:

GLBenchmark 2.1—Egypt—Offscreen 720p

GLBenchmark 2.1—Pro—Offscreen 720p

The bigger worry is what happens when the first 1920 x 1200 enabled Tegra 3 tablets start shipping. With (presumably) no additional GPU horsepower or memory bandwidth under the hood, we'll see this gap widen.

The Impact of Larger Memory A5X vs. Tegra 3 in the Real World
POST A COMMENT

232 Comments

View All Comments

  • name99 - Friday, March 30, 2012 - link

    Compared to the iPad1, the screen is, IMHO slightly smoother and a lot more oleophobic (ie it's a lot easier to clean off fingerprints by wiping a cloth over it). I never had an iPad2 so I don't know if these improvements are new or came with iPad2. Reply
  • shompa - Friday, March 30, 2012 - link

    See = AppleTV
    Touch = Ipad.

    But there was rumors about touch feedback from the screen. Probably in the next Ipad.
    Reply
  • rakez - Friday, March 30, 2012 - link

    as long as they stick with 4:3 i will never buy it. Reply
  • darkcrayon - Friday, March 30, 2012 - link

    Similarly, that's one of the best things about the iPad. I can't see using a widescreen tablet in portrait mode, there is pretty much no popular content that works well there. On the other hand, 4:3 isn't as good for video, but the net effect is that the video is just smaller. I'll take properly positioned and scaled documents and smaller video over larger video and tiny documents. Reply
  • shompa - Friday, March 30, 2012 - link

    You know that 16:9 is interesting if movies is the only thing you want to do.
    If you want to work on a tablet 16:9 does not work. You cant use landscape mode and see enough of the screen when you type. The 4:3 sceen is a bold move against tech nerds. I bet you are one of the tech nerds that screems when there are black bars on the side on you 16:9 TV. "why aren't the TV shows using the whole screen".
    Then stupid TV people listen to you and crop 4:3 TV shows to fit 16:9 and cutting of large part of the picture.

    The whole 16:9 debacle is actually a step backwards for the computing industry. Apple introduced widescreen displays early 2000. Steve made a great choose in 16:10. 2004 Apple invented the 2560x1600 screen. 16:10. Today its almost impossible to get a 16:10 screen. We all use TV LCDs for our computers = 16:9. 2560x1440. You loose 10% of real estate.
    Reply
  • KoolAidMan1 - Saturday, March 31, 2012 - link

    4:3 is better for web browsing and applications on a screen that size, the vertical room in landscape is great. It also makes for a much better balanced feel when holding it in portrait mode.

    Do you also like 16:9 on a desktop monitor? I sure don't, not unless it 27" 2560x1440
    Reply
  • rakez - Saturday, March 31, 2012 - link

    it's hard to argue with isheep and their products designed by god. i am pretty sure i know what i like more than someone else would know what i like. that being said, once again i prefer to not have 4:3 on my tablet. to each his own, Reply
  • Formul - Saturday, March 31, 2012 - link

    starting with isheep and ending with "to each his own" ... you do love your bipolarity, don't you? Reply
  • rakez - Saturday, March 31, 2012 - link

    sounds like i hit a nerve. go ahead keep following the herd. in the meantime i will buy what i want. Reply
  • PeteH - Monday, April 02, 2012 - link

    Out of curiosity, what do you dislike about the 4:3 aspect ratio, and what's your preferred aspect ratio? Reply

Log in

Don't have an account? Sign up now