domingo, 7 de outubro de 2012

Qualcomm Snapdragon S4 Review: Blazingly fast

Qualcomm has been one of the top SoC vendors since the release of its Snapdragon S4 Plus dual-core SoC, which, despite not being the best performing SoC of the time, had the luxury of LTE, and great power efficiency. Now, Qualcomm has impressed us again with a Quad-core variant of the Snapdragon S4, plus, it is the first SoC to use the revolutionary new Adreno 320 GPU, which is the first GPU to support OpenGL ES 3.0, and is the best performing mobile GPU ever seen (even better than the PowerVR SGX543MP3 in the iPhone 5). This impressive performance, coupled with LTE modems and the best power efficiency available today, results in what might be just about the perfect SoC.



Qualcomm Snapdragon S4 Pro
CPU 1.5-1.7GHz Quad-core Krait
L2 Cache 2MB
GPU Adreno 320
Memory Interface Dual-channel, 533MHz (presumably LPDDR2)
Process Technology 28nm
Connectivity 3G + 4G LTE

The CPU

The CPU in the Snapdragon S4 Pro is truly impressive. It is based on Qualcomm's own Krait CPU architecture, which is based on the ARM Cortex-A15 processor. The Krait offers much better power efficiency and about 50% better per-core efficiency than the current Cortex-A9. When Qualcomm released the dual-core Krait, it proved to offer comparable performance to quad-core Cortex-A9 SoCs, like the NVIDIA Tegra 3, losing only by small margins in a number of multi-threaded benchmarks, and, of course, being the best processor in any single-threaded benchmark. Now, Qualcomm doubled the already good performance that the dual-core Krait could deliver with the quad-core Krait variant. Unlike NVIDIA, Qualcomm changed L2 CPU cache accordingly to the increase in core count, bringing the L2 cache up to 2MB, so we won't be seeing any performance bottlenecks because of the L2 cache, again, unlike the Tegra 3. The S4 Pro can also deliver this beastly performance with the best power efficiency, as well as good thermal efficiency, thanks to the 28nm process used by Qualcomm. All this makes the Quad-core Krait just about the best mobile CPU ever created. 

The GPU

The Snapdragon S4 Pro is the first SoC to use the latest Adreno 320 GPU. The Adreno 320 is an excellent GPU, and is quite revolutionary, too. It is the first GPU to support OpenGL ES 3.0, and is also the best performing GPU ever created so far. Not much is known about the architecture of the Adreno 320, except that it has a unified shader architecture (no complaints here). At any rate, when comparing the Adreno 320's performance to the current king, the iPhone 5, powered by a PowerVR SGX543MP3, we get many mixed results, furthermore, it is very difficult to determine whether the Adreno 320 is ultimately better than the SGX543MP3 or not. However, the benchmark that most realistically tests gaming performance is the GLBenchmark 2.5 Egypt HD test.






As I said, these tests show some pretty mixed results. The Adreno 320 still lags behind the SGX543MP3, and, by extension, the lower-clocked SGX543MP4 in the iPad 3, in terms of triangle throughput and fill rate.  All of the devices tested have a HD 1280 x 800 screen (plus or minus), so we can't blame resolution for any differences here. Of course, the Adreno 320-powered Xiaomi MI 2 does outperform the iPhone 5 in the offscreen Egypt HD offscreen test, and also, the Adreno 320 performs remarkably similarly to the iPhone 5 in the Egypt HD onscreen test (4508 frames for the Xiaomi MI 2 vs 4509 frames in the iPhone 5), and again, we must remember that the Egypt tests are the ones that most accurately test how gaming performance is in real-life situations, so despite the fact that the iPhone 5 pulls ahead in low lever 3D tests, the Adreno 320 should offer about equal performance in games. We can be sure, too, that the Adreno 320 is by far the best GPU in the Android space. Specifically in the Egypt HD tests, it makes both the Mali-400MP and the NVIDIA Tegra 3 look ridiculously slow. Of course, the Adreno 320 is that powerful because it will have to offer good performance for the next-gen OpenGL ES 3.0. For now, the Adreno 320 is the best GPU on the Android space, and the only OpenGL ES 3.0-capable one, but I'm not sure if it will survive the onslaught of other OpenGL ES 3.0 GPUs coming soon, specifically, ImgTec's PowerVR 6 Rogue, ARM's Mali-T6xx, and NVIDIA's Tegra 4 'Wayne'. We'll see soon enough.

Conclusion

As we have seen, the Snapdragon S4 Pro has proved to be, as I see it, the perfect SoC. It offers the best performing CPU ever seen in a mobile device, and also one of the most efficient ones, it offers the best GPU in the Android space (and also gives the iPhone 5's GPU quite a run), all with the best thermal and power efficiency, thanks to Qualcomm's 28nm process, and, of course, Qualcomm's major selling point, LTE-capable modems. The only way I can see someone criticizing the S4 Pro is saying that it is just unnecessarily powerful! The only problem is how long will it be the best SoC. I see one possible danger for Qualcomm, which is NVIDIA's upcoming Tegra Wayne SoC, which is rumored to pack a quad-core Cortex-A15 CPU, with an additional battery saver core (the battery saver core would make the CPU even less power consuming than the S4 Pro), which would outperform the S4 Pro because it will probably run at higher clock speeds, as well as a Kepler-based, CUDA-compliant (GPGPU!) GeForce GPU, which will probably outperform the Adreno 320, but with the additional excellent power efficiency from the Kepler architecture, a move to 28nm process, and will have NVIDIA's own Icera LTE modem. The worst news is, the Tegra 4 can't be far from its announcement, considering that Tegra 3's now almost one year old. Watch out, Qualcomm! At any rate, at the moment the S4 Pro is the best SoC ever made, and is a truly impressive chip. Kudos to Qualcomm!

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