The Apple iPad Review (2012)
by Vivek Gowri & Anand Lal Shimpi on March 28, 2012 3:14 PM ESTGPU 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.
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:
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:
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.
234 Comments
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seanleeforever - Thursday, March 29, 2012 - link
Correction: YOU won't buy it doesn't mean the rest of us won't buy it.PS3/XBOX came out in 2005, or about 7 years now. i have no issues buying the latest game and still play.
what phone or pad did you have 7 years ago? oh, you have nothing... heck, the phones/pads you bought 3 years ago probably wont' be able to run today's game.
tipoo - Wednesday, March 28, 2012 - link
Tegra Zone enhancements, the article mentions that.PeteH - Wednesday, March 28, 2012 - link
What mechanism is being used to upscale legacy (1024x768) apps? Pixel doubling? Bi-cubic? Bi-linear? Something else?Guspaz - Wednesday, March 28, 2012 - link
At the most basic level, pixel doubling. However, text that is rendered through iOS gets a free resolution boost so long as the app was compiled with the latest version of xcode. It's pretty common on the iPad 3 to see apps where the interface elements are low-res, but all the text is high-res. And in apps that are predominantly text (like an SSH client, for example), that's all that really matters. Who cares if the triangle picture on a button isn't high res?For stuff like games, that stuff is just pixel doubled.
PeteH - Wednesday, March 28, 2012 - link
I'm not saying you're wrong, but how do you know games (for example) utilize pixel doubling?Guspaz - Wednesday, March 28, 2012 - link
I know because I can look at a game that doesn't support the new screen (such as Plants vs Zombies HD) on my iPad 3 and see that it's using pixel doubling? It does the same for iPhone apps when you use the 2x zoom option. One thing I have not tried is an old 320x480 iPhone app. I'm curious, since that would require 4x zoom.Newer games may choose to render at a lower resolution and then upscale using some sort of filter (perhaps even on the GPU), but at that point they are specifically targeting the new display. An older game that is completely oblivious to the newer display is scaled by the OS using pixel doubling without any interaction from the game.
Steelbom - Thursday, March 29, 2012 - link
Actually, when using iPhone apps, the iPad uses the 640x960 version rather than the 320x480 version, if available.mosu - Wednesday, March 28, 2012 - link
A person in his 50's doesn't care about 300dpi res because he only sees 200dpi, so retina display is just for kids? I really don't get why Apple did not use a standard res panel like 1920x 1200 if they wanted a greater quality image.It means they're stuck with a single form factor?PeteH - Wednesday, March 28, 2012 - link
It's much easier to stick with a single aspect ratio, especially for the developers. Your app looks the same on every device (albeit sharper on higher DPI displays), no need to tweak things for multiple aspect ratios.Sabresiberian - Thursday, March 29, 2012 - link
Umm, where do you get this idea?Generalized statements about vision limitations in humans are usually taken out of context, at best.
;)