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
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  • kwamayze - Friday, March 30, 2012 - link

    WOW!!! What a nice review!!! Well done Reply
  • michalkaznowski - Saturday, March 31, 2012 - link

    Just to say as always a brilliant view. Your site is a must view for any enthusiast here in the UK. I also have appreciated your wireless router reviews of the Airport Extreme Base Station. Only you have pointed out that it has a quantum leap stability when compared to other makes of routers, something that a group of us have had to find out a very hard, frustrating and long way!

    Michal
    Reply
  • x0rg - Saturday, March 31, 2012 - link

    I have a suggestion. Instead of taking pictures you could take screenshots of these devices when you show how beautiful the screen is while working with Remote Desktop. Pictures taken with the camera look terrible and the whole concept of taking pictures instead of screenshots seems unprofessional for the portal like AnandTech. Things like focus, gamma, apperture are not affecting the picture quality when you just take a screenshot (Home+Power on iPad, you know that). Please replace these terrible pictures with screenshots. Thank you. Reply
  • slashbinslashbash - Sunday, April 01, 2012 - link

    You missed the whole point of that part of the review. The point of the photos was to show that the text over Remote Desktop is actually readable in real-world use. A screenshot wouldn't convey that information.

    Imagine this. Say you took an iPhone 4 screenshot of the same scene in Remote Desktop, and you posted it on the site. This would be a 640x960 pixel image. Text would be readable on a desktop monitor, but it would probably not be readable on the actual 3.5" iPhone screen. That is the question, and it applies equally to the iPad3 review. A screenshot just shows you what pixels the iPad is showing; a photo shows you how those pixels look in real-life.
    Reply
  • x0rg - Thursday, April 05, 2012 - link

    I agree, my bad. Reply
  • TekFanChris - Sunday, April 01, 2012 - link

    Thank you Anand and Vivek! You guys always take the iPad reviews to the next level. Comprehensive and complete.

    Cheers.
    Reply
  • Death666Angel - Monday, April 02, 2012 - link

    That kinda reminded me of the PS2 vs PC quality back in the days. :D Reply
  • josemonmaliakal - Monday, April 02, 2012 - link

    Hi Your article seems be so good . And i have got something about the upcoming iPhone 5 of Apple here @ http://wp.me/p2gN9B-lq Reply
  • Wardawg - Thursday, April 05, 2012 - link

    You forget the new iPad just came out 95% of the apps have not upgraded for the new retina display yet. So all of these comparisons are very inaccurate. It doesn't matter that the iPad has higher res and 3.1 million pixels if the app isn't upgraded for retina display it won't display as such you would expect. I expect you guys to make a new article soon fixing these concerns of mine with this article. Reply
  • Noobuser45 - Monday, April 09, 2012 - link

    Anand, you're the only tech expert that I trust so I would love to have my mind put at ease with a definitive answer from you. Is it fine to charge the iPad whenever you want? Can I charge without running it down first? Can I charge for a while and unplug it before it has reached a full charge? Can I use it while it's charging? I just don't want to screw up the battery life. Reply

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