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Samsung Exynos 4210:
- Samsung Galaxy S2 (Exynos 4210 with ARM Mali400MP GPU)
Texas Instrument OMAP4:
- LG Optimus 3D (1GHz TI OMAP 4430 with PowerVR SGX540 @300MHz)
- Samsung Galaxy S2 GT-i9000G (1.2GHz TI OMAP 4430 with PowerVR SGX540 @300MHz)
- Motorola RAZR (1.2GHz TI OMAP 4430 with PowerVR SGX540 @300MHz)
- Samsung Galaxy Nexus (1.2GHz TI OMAP 4460 with PowerVR SGX540 @384MHz)
Mali400MP vs PowerVR SGX540
At first, Mali400MP appears to have the lead. It has higher fill-rate rating and was released a generation after PowerVR SGX540. Furthermore, Samsung chose Mali400MP in their Galaxy S2 phones after choosing PowerVR SGX540 in their original Galaxy S phones so naturally everyone will assume Mali400MP will be better. Mali400MP is suppose to be a 4-core design, so this further emphasize its higher theoretical performance potential.
So what happened here? Why is Galaxy S2 producing Smartbench 2012 Gaming results that barely exceeds the Galaxy S results, while lacking other OMAP 4 based phones?
Let's have a look at this diagram:
ARM's Mali design allows each vendor to choose how much 'cores' they wish to include in their implementations. In case of Samsung, they chose to go with the maximum number - 4. But as you can see here, only the Fragment Processor has been increased to 4. Vertex Processor still remains at 1.
What does all this mean?
This means, if the rendering scene contains a lot of vertices (or triangles), there will be a bottleneck. And this is exactly what's happening in case of Smartbench 2012, especially in the 'Shark' test. In this test, the shark object contains tens of thousands of triangles.
Why did ARM choose this design? Perhaps they thought for this time around, games for mobile devices won't approach the vertex limit of this processor, just yet. Long time ago, PC industry went through a similar phase. Eventually, games started to demand more from the GPU hence GPU manufacturers started implementing more bandwidth into Vertex Processors, by adding more cores and increasing clock.
In summary, Mali400MP will perform fine if your game stresses rendering more than pushing through shear number of polygons. As polygon count increases, Mali400 will start to show its limit.
Keep in mind that the original Galaxy S series used the same PowerVR SGX540 GPU, but they were only clocked at 200MHz. So everything else being equal, OMAP4 based phones will execute GPU instructions at least 50% faster. OMAP 4460 will be nearly 2x faster.
Overclock-ability
Samsung's Exynos 4310 SoC was designed to operate at 1.2GHz and current phones using this processor already runs at this clock speed. In contrast, OMAP 4460 processor was designed to operate at 1.5GHz but the Galaxy Nexus was under-clocked at 1.2GHz, presumably to improve battery life. This also means Galaxy Nexus will easily "over-clock" to 1.5GHz with relative ease. OMAP 4430 was designed to operate at 1.2GHz so there's no more headroom than Exynos 4210, at least in theory. With further overclocking, the GPU will overclock by a similar ratio, hence resulting in further performance improvement.
Summary
Could older Power SGX540 really perform faster than Mali400MP? Could Galaxy S beat out Galaxy S2?
The answer in this case is no. 200MHz SGX540 cannot beat Mali400MP. But higher clocking SGX540 in OMAP 4 can for some type of rendering scenes. The key point here is the number of polygons. Due to the inherent design of Mali4MP, it won't handle scenes with huge number of polygons very well. Unfortunately (for Mali400MP), some of Smartbench 2012 test suits do just that.
Does this mean Mali400MP is a bad GPU? Hardly. It simply means it won't execute all 3D tests fast. It is possible for 3D games designers to focus more on the rendering aspect (i.e. textures and effects) than accuracy of non-linear shapes (which require more polygons to more accurately approximate these shapes). Mali400MP's fill rates are excellent - better than SGX540. Some benchmark tests will prove this.
It will be interesting how the gaming market evolves during 2012. iPhone 4S and iPad uses SGX chips without this limitation. If game designer decides to jointly develop games for both platforms (iOS and Android), Mali400MP may have issues. On the other hand, games may not hit this bottleneck during this year and by then, the next iteration of Mali GPU could take care of this 'issue'.
