The Mali-400

Now that we've settled the issue of what type of GPU it is, let's talk about the physical makeup of the Mali-400. The Mali-400 isn't a unified shader architecture, it has discrete execution hardware for vertex and fragment (pixel) processing. ARM calls the Mali-400 a multicore GPU with configurations available with 1 - 4 cores. When ARM refers to a core however it's talking about a fragment (pixel shader) processor, not an entire GPU core. This is somewhat similar to NVIDIA's approach with Tegra 2, although NVIDIA counts each vertex and fragment processor as an individual core.

In its simplest configuration the Mali-400 features a single combined geometry front end and vertex processor and a single fragment processor. The 400 is also available in 2 and 4 core versions, both of which still have only a single vertex processor. The two core version has two fragment processors and the four core version has four fragment processors. Note that ARM decided to scale fragment shading performance with core count while keeping vertex performance static. This is likely the best decision given current workloads, but a risky one. NVIDIA on the other hand standardized on a 1:1 ratio between fragment and vertex processors compared to ARM's 4:1 on a 4-core Mali-400. The 4-core Mali-400 MP4 is what Samsung uses in the Exynos 4210.

ARM, like Qualcomm, isn't particularly interested in having the details of its GPUs available publicly. Unfortunately this means that we know very little about the makeup of each of these vertex and fragment processors. I suspect that both companies will eventually learn to share (just as AMD and NVIDIA did) but as this industry is still in its infancy, it will take some time.

Earlier documentation on Mali revealed that the GPU is a VLIW architecture, meaning each processor is actually a collection of multiple parallel execution units capable of working on vector data. There's no public documentation indicating how wide each processor is unfortunately, but we can make some educated guesses.

We know from history that AMD felt a 5-wide VLIW architecture made sense for DX9 class games, later moving down to a 4-wide architecture for DX11 games. AMD didn't have the die constraints that ARM and other SoC GPU suppliers do so a 5-wide unit is likely out of the question, especially considering that Imagination settled on a VLIW4 architecture. Furthermore pixels have four color elements (RGBA), making a VLIW4 an ideal choice.

Based on this as well as some internal information we can assume that a single Mali fragment shader is a 4-wide VLIW processor. The vertex shader is a big unknown as well, but knowing that vertex processing happens on two coordinate elements (U & V) Mali's vertex shader is likely a 2-wide unit.

Thus far every architecture we've looked at has been able to process one FP16 MAD (multiply+add) per execution unit per clock. If we make another assumption about the Mali-400 and say it can do the same, we get the following table:

Mobile SoC GPU Comparison
  PowerVR SGX 535 PowerVR SGX 540 PowerVR SGX 543 PowerVR SGX 543MP2 Mali-400 MP4 GeForce ULP Kal-El GeForce
SIMD Name USSE USSE USSE2 USSE2 Core Core Core
# of SIMDs 2 4 4 8 4 + 1 8 12
MADs per SIMD 2 2 4 4 4 / 2 1 ?
Total MADs 4 8 16 32 18 8 ?
GFLOPS @ 200MHz 1.6 GFLOPS 3.2 GFLOPS 6.4 GFLOPS 12.8 GFLOPS 7.2 GFLOPS 3.2 GFLOPS ?
GFLOPS @ 300MHz 2.4 GFLOPS 4.8 GFLOPS 9.6 GFLOPS 19.2 GFLOPS 10.8 GFLOPS 4.8 GFLOPS ?

Based on this estimated data alone, it would appear that a four-core Mali-400 has the shader compute power of a PowerVR SGX 543. In other words, half the compute horsepower of the iPad 2's GPU or over twice the compute of any smartphone GPU today. The Mali-400 is targeted at 275MHz operation, so its figures are likely even higher than the competition. Although MADs are quite common in shader execution, they aren't the end all be all - we need to look at application performance to really see how it stacks up.

Understanding Rendering Techniques GPU Performance: Staggering
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  • Deann - Friday, October 07, 2011 - link

    Maybe I misunderstood, but if you take a look at this swedish website the Samoled + looks much better than the Amoled: http://www.appsandroid.dk/joomla/skaermtest-af-htc... Reply
  • aritai - Saturday, October 08, 2011 - link

    You may want to consider counting number of web pages browsed before battery exhaustion and report those as well. Perhaps even calculate a "joules per page viewed" as part of your power metrics. (i.e. it may be that running at max benchmark rate on a more powerful system displays twice as many pages - and that these systems are being penalized for not being as slow as their competitors - where in terms of raw energy usage they would last longer than their slower competitors if asked only to do the same amount of work). Reply
  • Paulman - Thursday, October 20, 2011 - link

    I just started reading some comments about upgrading the Galaxy S II to 2.3.5 of Gingerbread, and people are reporting improvements in the sound quality. They were quite surprised! Do you think one of you / Francois can take the time to look into it? Thanks. Reply
  • san3536 - Friday, October 28, 2011 - link

    Hi
    I am planning to buy a Samsung Galaxy S2 in US and to use it in India.... is it possible that way to use it in different country ? i would like to know what are specifications to be asked for the same like unlocked & International etc ... does unlocked mean just it can be used on any network only in US or else where or is international version mandatory ? please inform the disadvantages of using the phone in India which is brought in US ...like any of phone functions wont work etc ..
    Reply
  • Naengmyun - Monday, November 21, 2011 - link

    Me and about a gazillion of my GS2 owners are experiencing problem connecting to our home WiFi networks. Everything, including visitors' laptops, iPads, Android Tablets, smartypwns, netbooks and even the kitchen sink connect seamlessly to my Great Home WiFi Network. But not the GS2! Amazing. Everyone's playing the blame game for now~provider says it's the router, router tech support says it's the phone, Samsung says it's me, phone carrier wants to know if I'd be interested in their latest unlimited plan.
    Anyone else having trouble with GS2 WiFi connectivity?

    Bibm
    Reply
  • Ravil - Saturday, November 26, 2011 - link

    i bought the samsung galaxy s2 from sri lanka for LKR85,000/= on the 4th of november 2011 with android 2.3.3 and i have some issues with it.

    1) screen issue
    when the phone is on the lowest brightness level the left part of the screen has a yellowish tint and i took it to the sri lankan warranty agents THE PHONE COMPANY four times and they replaced the screen and now its worse now the whole screen has a yellowish tint.

    2) signal issue
    the signal is unstable signal bars are at 2bars sometimes 3bars sometimes full and when i connect to the in ternet it connects from hsdpa and edge, when i'm not connected to the internet it shows the 3g icon, the above mentioned warranty agents THE PHONE COMPANY replaced the motherboard but i still have the issue.

    3) no NFC
    i don't have NFC (near field communication)

    pls help me with these issues can samsung replace the whole phone and give me a new one?
    my email address is ravildealwis7@gmail.com
    Reply
  • sgxsingapore1 - Friday, February 03, 2012 - link

    Singapore Exchange (SGX) is working with Singapore's first futures brokerage on a professional traders development programme,SGX Singapore : Live News & Updates from SGX Singapore .These were among the most active shares in the market <a href="http://sgxsingapore.com/">SGX Singapore</a> Reply
  • sgxsingapore1 - Friday, February 03, 2012 - link

    Singapore Exchange (SGX) is working with Singapore's first futures brokerage on a professional traders development programme,SGX Singapore : Live News & Updates from SGX Singapore .These were among the most active shares in the market SGX Singapore Reply
  • sgxsingapore1 - Friday, February 03, 2012 - link

    Singapore Exchange (SGX) is working with Singapore's first futures brokerage on a professional traders development programme,SGX Singapore : Live News & Updates from SGX Singapore .These were among the most active shares in the market <a href="http://sgxsingapore.com/">SGX Singapore</a> Reply
  • Jedi2155 - Tuesday, February 21, 2012 - link

    I have an Epic 4G (Original SGS), and I have to say the audio quality is horrendous compared to an iPhone, Creative Zen X-Fi, and my home X-Fi on my PC. Nothing compares, especially since I hear some clear static even though nothing is playing pointing to poor isolation. To say that the original SGS phones were good sound quality (my sister's also has the same Epic 4G with same issue) would be hard to swallow based on my personnel experience. Reply

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