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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  • VivekGowri - Sunday, September 11, 2011 - link

    I literally cannot wait to read this article, and I similarly cannot wait for SGS2 to launch in the US. Reply
  • ImSpartacus - Sunday, September 11, 2011 - link

    You guys don't get early access to drafts? Reply
  • niva - Monday, September 12, 2011 - link

    I own an original Galaxy S, until it's been proven that Samsung updates to the latest Android within a month after major releases I will not buy anything but a Nexus phone in the future (assuming I even go with Android). By the time that decision has to be made I'm optimistic there will be unlocked WP7 Nokias available. Reply
  • Havor - Monday, September 12, 2011 - link

    Seriously , whats the problem, I was running 2.2 and 2.3 when they came out, could have them sooner, I just dont like to run roms with beta builds.

    So you never heard of Rooting and Custom Roms?

    Its the nature of companies to have long and COSTLY eternal testing routs, done mainly by people with 9 to 5 jobs, as delivering buggy roms is bad for there name, but then so is not updating to but its lots less hurtful, as most people dont care or know any better.

    Next to that if your phone is a phone is customized with extra crapeware by your provider it can be that it takes months before you get a update even do Samsung delivered one a long time ago.

    The rooting scene is totally different, its done by nerds with passion for what they do, and yes the early/daily builds have bugs but also get mouths quicker reported and fixed by the scene.
    And imho are the final updates just as stable as the factory builds.

    Dont like how your Android is working?
    Stop bitching and fixed your self, its not that hard, as it is a OS platform, just make sure you can root your phone, before you buy it.

    The following website explains it all.
    http://androidforums.com/galaxy-s-all-things-root/...
    http://androidforums.com/galaxy-s-all-things-root/
    Reply
  • vision33r - Monday, September 12, 2011 - link

    If it's your personal phone, you can do whatever you want. However like some of us here with jobs that let us pick phones. One requirement is the phone has to be stock and no rooting allowed.

    Samsung is about the worst of the 3 makers in terms of software updates.
    Reply
  • niva - Monday, September 12, 2011 - link

    Seriously calm down, I've heard plenty about rooting and custom roms but phone hackery is not something I'm interested in right now. I don't have the time or energy for it. I shouldn't have to manually go through rooting and updating my phone, especially when security issues are involved.

    I like the way 2.2 is working on the SGS. I bought this phone from a friend who upgraded and it's not something I would've paid the retail price for. I've not run into anything so far that's made me actually bother with the rooting and manual upgrade process. I've not read into rooting the phone or updating it, but I'm sure if I get into it this will take me a long time (hours/days) which I shouldn't need to sacrifice to run the latest version of the OS.

    From the political standpoint the blame is both on Samsung and T-Mobile apparently in terms of getting the new revisions out.

    From my personal standpoint I despise all companies who do not use the default Android distro, running skins and secondary apps, on the phones they ship out. While some of the things they do are nice, it slows down their ability to keep up with android revisions.

    On the other hand, my wife's Nexus (original one) updates faster than internet posts saying Android 2.3.x has been rolled out. It's friggin awesome. She had one problem with battery draining really fast after a recent upgrade but I managed to fix that after a couple of hours of forum searching and trying different things.

    So it's simple, if I will buy another Android in the future, it will be a Nexus phone, where I know from personal experience that everything works in terms of having the latest and greatest. Notice the Nexus S is made by Samsung, it's for the most part identical to the phone I have, yet gets the updates immediately and doesn't have the known security problems I'm exposed to.
    Reply
  • ssj4Gogeta - Monday, September 12, 2011 - link

    Well, the international version got 2.3.3 around ~3 months ago here (and earlier for other countries). Reply
  • poohbear - Tuesday, September 13, 2011 - link

    vision33r u dont know what you're talking about. People bitch and complaina bout software updates, but how are the quality of those updates? when its updated too soon there are bugs and ppl complain, updated later ppl complain about the wait times. I remember last year Motorola said they're not updating their XT720 to android 2.2., they're leaving it at 2.1. S korea Motorola was the only branch that decided to do it, but guess what? 2.2 was too much for the hardware in the XT720 to handle, and it ran slooooow! XT720 users all over complained about it, but the reality is the phone couldnt handle it. 90% of smartphone users want something stable that works, they dont care about having the latest and greatest Android build. So if Samsung errs on the side of quality and takes more time to release stable quality software, then all the power to them! Reply
  • anishannayya - Friday, September 23, 2011 - link

    Actually, if updates are your hard-on, then you'd likely be looking at Motorola in the future (due to the Google acquisition).

    The entire reason why the Nexus lines of phones are quick to get updates is because the are co-developed with Google. As a result, these phones are the ones the Google developers are using to test the OS. When it is ready to go, it is bug free on the device, so Samsung/HTC can roll it out immediately.

    At the end of the day, any locked phone is plagued by carrier bloatware, which is the biggest slowdown in software release. Just buy an unlocked phone, like this one, in the future.
    Reply
  • ph00ny - Sunday, September 11, 2011 - link

    It's awesome to see this article finally
    I'm glad François Simond aka supercurio contributed to the article

    Btw that slot on the left is for the hand strap which is very popular in asia for accessory attachments
    Reply

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