In our discrete GPU reviews for the desktop we've often noticed the tradeoff between graphics and compute performance in GPU architectures. Generally speaking, when a GPU is designed for compute it tends to sacrifice graphics performance or vice versa. You can pursue both at the same time, but within a given die size the goals of good graphics and compute performance are usually at odds with one another. 

Mobile GPUs aren't immune to making this tradeoff. As mobile devices become the computing platform of choice for many, the same difficult decisions about balancing GPU compute and graphics performance must be made.

ARM announced its strategy to dealing with the graphics/compute split earlier this year. In short, create two separate GPU lines: one in pursuit of great graphics performance, and one optimized for graphics and compute.

Today all of ARM's shipping GPUs fall on the blue, graphics trend line in the image above. The Mali-400 is the well known example, but the forthcoming Mali-450 (8-core Mali-400 with slight improvements to IPC) is also a graphics focused part.

The next-generation ARM GPU architecture, codenamed Midgard but productized as the Mali-T600 series will have members optimized for graphics performance as well as high-end graphics/GPU compute performance.

The split looks like this:

The Mali-T600 series is ARM's first unified shader architecture. The parts on the left fall under the graphics roadmap, while the parts on the right are optimized for graphics and GPU compute. To make things even more confusing, the top part in each is actually a second generation T600 GPU, announced today.

What does the second generation of T600 give you? Higher IPC and higher clock speeds in the same die area thanks to some reworking of the architecture and support for ASTC (an optional OpenGL ES texture compression spec we talked about earlier today). 

Both the T628 and T678 are eight-core parts, the primary difference between the two (and between graphics/GPU compute optimized ARM GPUs in general) is the composition of each shader core. The T628 features two ALUs, a LSU and texture unit per shader, while the T658 doubles up the ALUs per core.

Long term you can expect high end smartphones to integrate cores from the graphics & compute optimized roadmap, while the mainstream and lower end smartphones wll pick from the graphics-only roadmap. All of this sounds good on paper, however there's still the fact that we're talking about the second generation of Mali-T600 GPUs before the first generation has even shipped. We will see the first gen Mali-T600 parts before the end of the year, but there's still a lot of room for improvement in the way mobile GPUs and SoCs are launched...

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  • lilmoe - Saturday, August 11, 2012 - link

    I understand all that... Samsung is releasing the Exynos 5 Dual for the sole purpose of supporting a higher resolution on a tablet (higher than FHD). It's becoming a race of who has the faster GPU when it comes to Android, while NONE of the applications are hitting the surface when it comes to fully taking advantage of it. Even Asus's Full HD tablets are running on Tegra3.

    None of the OEMs are announcing any Android tablets with the Adreno 320. Those who are announcing them have Windows RT in mind. Which only means one thing; they can really be utilized under Windows, not Android.

    It's a complete waste. The t600 series needs really good dev support to really shine. Devices running the t604 will be extremely limited compared to Android as a whole...

    That's one part of the rant. The other part revolves around the release date of the second generation T600 series which makes the new Exynos' GPU obsolete (by ARM's standards) before it was even released. What's even more frustrating is that the "second generation" is nothing but a refinement of the first one with added support for ASTC...
  • darckhart - Monday, August 6, 2012 - link
  • whooleo - Monday, August 6, 2012 - link

    I'm still waiting for this "console class performance" they keep talking about. The Xbox 360 when optimised very well has the performance roughly of a 8800 GT or 9600 GT if you want to be conservative. These mobile GPUs aren't near that level of performance yet. Marketing, all about stretching the truth.
  • augiem - Monday, August 6, 2012 - link

    I saw some commentary a while back saying these GPUs would probably reach X360 levels some time in 2014. I'd probably guess a bit longer than that, but it's to be expected. They're both very low power and physically tiny parts. Yeah, the hype is just hype as always. Mobile will never be equal to desktop performance, it just makes sense. As it stands, if we reach X360 performance in 2014, that will be about a 10 year gap. The gap may close a bit with the huge money going into mobile development, but I doubt you'll ever see less than a 5 year gap between desktop and mobile parts.
  • augiem - Monday, August 6, 2012 - link

    Oops, X360 came out in 2005, so 9 year gap, not 10.
  • whooleo - Monday, August 6, 2012 - link

    I agree but I just wish we could have a solid comparison between desktop and mobile parts.
  • Lucian Armasu - Friday, August 10, 2012 - link

    The gap is more like 7 years. The "console class" performance should come next year with the arrival of Mali T628 and T658, which should have close to 300 gigaflops, more than Xbox360 and PS3. Also these new chips have support for OpenGL ES 3.0, while PS3 only supports OpenGL ES 2.0 (slightly modified), so the games should look more visually impressive, too, if the devs actually make them specifically for those chips, like they do with Tegra optimized games.
  • dishayu - Tuesday, August 7, 2012 - link

    LOL!! No!! Where do you get that information from? An Xbox 360 has roughly half the power of a 8800GT. Because, it's pretty much an ATI X1800 which fell short of the 7800GTX, which is not much more than half as powerful as a 8800GT.

    And when talking console class, why do you want to go high-er end console that XBox 360 is? If you take the case of Nintendo Wii, that has roughly half the power of a Xbox 360, and phones are slowly getting to that level. Of course the marketing guys are exaggerating to sell their products but they aren't off by as much as you believe.
  • whooleo - Tuesday, August 7, 2012 - link

    As I said when optimised well (Crysis 2, Gears of War 3, FF XIII-2, etc.). An ATI X1800 you say? I don't think so, the Xenos has 48 unified R520 shaders, 8 ROPs, 16 TUs, and an 10MB eDRAM chip that when utilised well gives the Xbox 360 a big advantage over the X1800 or 8600 GT. Also take a look at the minimum requirements for a lot of multi-platform games out, Crysis 2 for example needs an 8800 GT at least for low settings and from what I remember one of the devs said that the lowest settings are about console quality. Now the 8800 GT could most likely run at higher resolutions and is why I say the 9600 GT is probably a better comparison.
  • steller2k - Tuesday, August 7, 2012 - link

    8800GT ?! I was running an 8600 GT in my main gaming PC until 6 months ago and it always outperformed my Xbox 360 in both resolution and detail. I'm not dogging the 360; it had great graphics when it debuted, but it was no where near the 8800 GT level.

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