The iPhone 5 Reviewby Anand Lal Shimpi, Brian Klug & Vivek Gowri on October 16, 2012 11:33 AM EST
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- iPhone 5
Section by Anand Shimpi
Understanding the A6's GPU architecture is a walk in the park compared to what we had to do to get a high level understanding of Swift. The die photos give us a clear indication of the number of GPU cores and the width of the memory interface, while the performance and timing of release fill in the rest of the blanks. Apple has not abandoned driving GPU performance on its smartphones and increased the GPU compute horsepower by 2x. Rather than double up GPU core count, Apple adds a third PowerVR SGX 543 core and runs the three at a higher frequency than in the A5. The result is roughly the same graphics horsepower as the four-core PowerVR SGX 543MP4 in Apple's A5X, but with a smaller die footprint.
As a recap, Imagination Technologies' PowerVR SGX543 GPU core features four USSE2 pipes. Each pipe has a 4-way vector ALU that can crank out 4 multiply-adds per clock, which works out to be 16 MADs per clock or 32 FLOPS. Imagination lets the customer stick multiple 543 cores together, which scales compute performance linearly.
SoC die size however dictates memory interface width, and it's clear that the A6 is significantly smaller in that department than the A5X, which is where we see the only tradeoff in GPU performance: the A6 maintains a 64-bit LPDDR2 interface compared to the 128-bit LPDDR2 interface in the A5X. The tradeoff makes sense given that the A5X has to drive 4.3x the number of pixels that the A6 has to drive in the iPhone 5. At high resolutions, GPU performance quickly becomes memory bandwidth bound. Fortunately for iPhone 5 users, the A6's 64-bit LPDDR2 interface is a good match for the comparatively low 1136 x 640 display resolution. The end result is 3D performance that looks a lot like the new iPad, but in a phone:
|Mobile SoC GPU Comparison|
|Adreno 225||PowerVR SGX 540||PowerVR SGX 543MP2||PowerVR SGX 543MP3||PowerVR SGX 543MP4||Mali-400 MP4||Tegra 3|
|# of SIMDs||8||4||8||12||16||4 + 1||12|
|MADs per SIMD||4||2||4||4||4||4 / 2||1|
|GFLOPS @ 200MHz||12.8 GFLOPS||3.2 GFLOPS||12.8 GFLOPS||19.2 GFLOPS||25.6 GFLOPS||7.2 GFLOPS||4.8 GFLOPS|
We ran through the full GLBenchmark 2.5 suite to get a good idea of GPU performance. The results below are largely unchanged from our iPhone 5 Performance Preview, with the addition of the Motorola RAZR i and RAZR M. I also re-ran the iPad results on iOS 6, although I didn't see major changes there.
We'll start out with the raw theoretical numbers beginning with fill rate:
The iPhone 5 nips at the heels of the 3rd generation iPad here, at 1.65GTexels/s. The performance advantage over the iPhone 4S is more than double, and even the Galaxy S 3 can't come close.
Triangle throughput is similarly strong:
Take resolution into account and the iPhone 5 is actually faster than the new iPad, but normalize for resolution using GLBenchmark's offscreen mode and the A5X and A6 look identical:
The fragment lit texture test does very well on the iPhone 5, once again when you take into account the much lower resolution of the 5's display performance is significantly better than on the iPad:
The next set of results are the gameplay simulation tests, which attempt to give you an idea of what game performance based on Kishonti's engine would look like. These tests tend to be compute monsters, so they'll make a great stress test for the iPhone 5's new GPU:
Egypt HD was the great equalizer when we first met it, but the iPhone 5 does very well here. The biggest surprise however is just how well the Qualcomm Snapdragon S4 Pro with Adreno 320 GPU does by comparison. LG's Optimus G, a device Brian flew to Seoul, South Korea to benchmark, is hot on the heels of the new iPhone.
When we run everything at 1080p the iPhone 5 looks a lot like the new iPad, and is about 2x the performance of the Galaxy S 3. Here, LG's Optimus G actually outperforms the iPhone 5! It looks like Qualcomm's Adreno 320 is quite competent in a phone. Note just how bad Intel's Atom Z2460 is, the PowerVR SGX 540 is simply unacceptable for a modern high-end SoC. I hope Intel's slow warming up to integrating fast GPUs on die doesn't plague its mobile SoC lineup for much longer.
The Egypt classic tests are much lighter workloads and are likely a good indication of the type of performance you can expect from many games today available on the app store. At its native resolution, the iPhone 5 has no problems hitting the 60 fps vsync limit.
Remove vsync, render at 1080p and you see what the GPUs can really do. Here the iPhone 5 pulls ahead of the Adreno 320 based LG Optimus G and even slightly ahead of the new iPad.
Once again, looking at GLBenchmark's on-screen and offscreen Egypt tests we can get a good idea of how the iPhone 5 measures up to Apple's claims of 2x the GPU performance of the iPhone 4S:
Removing the clearly vsync limited result from the on-screen Egypt Classic test, the iPhone 5 performs about 2.26x the speed of the 4S. If we include that result in the average you're still looking at a 1.95x average. As we've seen in the past, these gains don't typically translate into dramatically higher frame rates in games, but games with better visual quality instead.
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A5 - Tuesday, October 16, 2012 - linkDouble the browsing time while moving to LTE and roughly the same in everything else despite double the performance is pretty impressive.
rarson - Thursday, October 18, 2012 - linkI'm pretty sure they mentioned about a million times that "this is the new paradigm blah blah blah, where if you use heavy processing power more often, the battery life will diminish faster" (I'm paraphrasing here). I'm fine with that. The iPhone 5 shows some pretty impressive battery life in light workloads and doesn't actually do all that bad in heavy workloads despite how much number crunching it's doing, even though it might actually tank the battery life down to less-than-4S levels.
It's a tradeoff: you get more power or longer battery life, depending on how you use it. The article paints this as a bad thing, but I disagree; it's obviously making much more efficient use of the hardware. Because of that, I definitely think the battery life overall is better, even though sometimes it might be worse. And you're still getting a lot more number crunching for the watts used.
Center - Tuesday, October 16, 2012 - linkIn the intro, the screen specs on the iphone 5 is listed as 1136x960.. should be 1136x640.
But great article as always, Anandtech!
Krysto - Tuesday, October 16, 2012 - linkI hope we'll see the same kind of thorough review of Samsung's Exynos 5 Dual chip, Anand.
ltcommanderdata - Tuesday, October 16, 2012 - linkIsn't TI supposed to become the first shipping Cortex A15 SoC? I expect Anandtech to thoroughly review the first Cortex A15 SoC. There shouldn't be a need to go into the same detail (on the CPU side) for every subsequent one unless preliminary tests show something significantly different.
Kidster3001 - Monday, October 22, 2012 - linkSamsung and Qualcomm do not ship generic ARM chips. They purchase licenses to use the ARM instruction set, not the chip design. Their chips are highly customized and perform differently.
Using your logic to just review the first A15 class chip and consider the rest to be comparable is similar to just reviewing the first new car to be released every year and assume the rest will be comparable.
btw, TI is getting out of the business. I doubt they will ship first, or ever.
A5 - Tuesday, October 16, 2012 - linkConsidering the fact that Krait got several articles here, I'd imagine that whatever the first shipping A15 chip is will get significant coverage.
Wurzelsepp - Tuesday, October 16, 2012 - linkGreat review, you really have to give Apple credit for building an amazing SoC.
It's interesting to see how well the Adreno competes with SGX-543MP3, the new Nexus 4 with this GPU is going to be amazing.
Krysto - Tuesday, October 16, 2012 - linkOne thing both the iPhone and the Intel Atom processors will keep lacking for a year from now, will be OpenGL ES 3.0 support. Apple might bring it to the new iPad 4 this spring, but the iPhone won't have it until the next iPhone, in the fall of 2013, obviously. Same with Intel, they won't be supporting it at least until end of 2013.
In the meantime both Adreno 320 and Mali T604 are supporting it, and will come out this fall.
darwinosx - Tuesday, October 16, 2012 - linkA year from now and something 'coming out this fall". Right.