The iPhone Becomes a Gaming Platform: Enter the PowerVR SGX

Now that we’re familiar with the 3GS’ CPU, it’s time to talk about the GPU: the PowerVR SGX.

Those familiar with graphics evolution in the PC space may remember Imagination Technologies and its PowerVR brand by their most popular desktop graphics card: STMicro’s Kyro and Kyro II. The Kyro series used the PowerVR3 chips and while STMicro ultimately failed to cement itself as a NVIDIA competitor in the desktop, the PowerVR technology lived on in ultra-mobile devices.

The SGX is on Imagination Technologies’ fifth generation of its PowerVR architecture, and just like the Kyro cards we loved, the SGX uses a tile based renderer. The idea behind a tile or deferred renderer is to render only what the camera sees, not wasting clocks and memory bandwidth on determining the color of pixels hidden by another object in the scene. Tile based renderers get their name from dividing the screen up into smaller blocks, or tiles, and working on each one independently. The smaller the tile, the easier it is to work on the tile on-chip without going to main memory. This approach is particularly important in the mobile space because there simply isn’t much available bandwidth or power. These chips consume milliwatts, efficiency is key.

The MBX-Lite used in the original iPhone was also a tile based architecture, the SGX is just better.

Also built on a 65nm process the PowerVR SGX is a fully programmable core, much like our desktop DX8/DX9 GPUs. While the MBX only supported OpenGL ES 1.0, you get 2.0 support from the SGX. The architecture also looks much more like a modern GPU:

Pixel, vertex and geometry instructions are executed by a programmable shader engine, which Imagination calls its Universal Scalable Shader Engine (USSE). The “coprocessor” hardware at the end of the pipeline is most likely fixed-function or scalar hardware that’s aids the engine.

The SGX ranges from the PowerVR SGX 520 which only has one USSE pipe to the high end SGX 543MP16 which has 64 USSE2 pipes (4 USSE2 pipes per core x 16 cores). The iPhone 3GS, I believe, uses the 520 - the lowest end of the new product offering.

A single USSE pipe can execute, in a single clock, a two-component vector operation or a 2 or 4-way SIMD operation for scalars. The USSE2 pipes are upgraded that handle single clock 3 or 4 component vector operations, have wider SIMD and can co-issue vector and scalar ops. The USSE2 pipes are definitely heavier and have some added benefits for OpenCL. For the 3GS, all we have to worry about is the single USSE configuration.

  iPhone 3G (PowerVR MBX-Lite) PowerVR SGX @ 100MHz PowerVR SGX @ 200MHz
Manufacturing Process 90nm 65nm 65nm
Clock Speed ~60MHz 100MHz 200MHz
Triangles/sec 1M 3.5M 7M
Pixels/sec 100M 125M 250M

 

In its lowest end configuration with only one USSE pipe running at 200MHz, the SGX can push through 7M triangles per second and render 250M pixels per second. That’s 7x the geometry throughput of the iPhone 3G and 2.5x the fill rate. Even if the SGX ran at half that speed, we’d still be at 3.5x the geometry performance of the iPhone 3G and a 25% increase in fill rate. Given the 65nm manufacturing process, I’d expect higher clock speeds than what was possible on the MBX-Lite. Also note that these fill rates take into account the efficiency of the SGX’s tile based rendering engine.

Enter the ARM Cortex A8 Final Words: Preparing for 3GS
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  • jasaero - Friday, June 12, 2009 - link

    I am guessing Apple gets a better deal with Samsung as I think most of the flash in iPods was from them prior to iPhone. TI may make flash memory, but pretty sure they don't touch Samsung volume. From what I can gather also the Samsung ASIC and OMAP are pretty much the same anyhow or atleast have pretty close ARM/IM SoC matched lines. Reply
  • jasaero - Thursday, June 11, 2009 - link

    I am with you 100% on this. If you goto page 5 of these comments I linked to some good info on what is behind snapdragon and qualcomm's plans now that they own AMD/ATI handheld graphics IP. They also spent 100's of millions making their cortex core more powerful than the competition also. I am with you on Anand doing a more in depth look at the competing offerings here using his connections to get info tough to find for us. Its intersting stuff as this market is more IP oriented, but Qualcomm, intel and probably a lot of others add their own IP as they package these things in SoC's. Reply
  • iwodo - Friday, June 12, 2009 - link

    Yes I read it. On paper Qualcomm seems to have an edge on everything. ATI powered Graphics, Better then Cortex A8 design, and expertise in Mobile Wireless Chipset.

    However it doesn't seems any Manufacture are using their chips. From the charts Mainly Japaneses and Korean ( LG ) based phone maker. Given LG recently switched side to Non Qualcomm based to due to cost issues. We will see even less QualComm chip in Global Market since Japaneses Handset are not exported and unusable outside Japan.
    Reply
  • Barack Obama - Thursday, June 11, 2009 - link

    Was waiting to see what the fuss about Iphone 3G S was about. If I wasn't already tied down to a 2 year contract I'd buy one.

    Do you think Apple will gain dominance over the phone market as they seemingly are or other companies will get their feet in the door? Apple is looking at a Windows-like monopoly of the mobile phone market at the moment!
    Reply
  • anandtech02148 - Wednesday, June 10, 2009 - link

    these smartphones will eventually make PC, laptop, & netbook less rellevant, Apple already has 50,000 apps just for iphone, do they even have that much apps for their own macbook line?
    Intel,Amd & Nvidia is becoming a niche, with consoles and smartphone taking their customers away little by little.
    the only weakness to smartphone is how badly these cartel cellular operate. Get your acts together At&T and get aggressive broadband roll out.

    Reply
  • Mazik - Wednesday, June 10, 2009 - link

    "If Apple would just get their pre-ordering system working right I might not even have to camp out this year..."

    ...you can pre-order on att.com
    Reply
  • snookie - Wednesday, June 10, 2009 - link

    "Apple could be their own worst enemy with this faster hardware, and they have been seen to drop legacy support quite quickly already (Snow Leopard anyone?), things that other people can't get away with."

    Apple drop legacy support quite easily? No. You don't know anything about the history of Mac OS if you say that. Google Rosetta for one. Look at how long people are able to continue to install the latest Mac OS on old hardware for another. SL is a major rewrite of huge portions of the OS that Windows 7 could only dream about. It's the kind of rewrite that Microsoft doesn't have the skills, the will, or organization to do.

    "Palm has the Pre, it has faster hardware."

    Not anymore. Read the article.

    "The problem here is that either Apple developers are going to have to develop for the (s)lowest common denominator (20million units), and either risk annoying customers by making them unable to use the stuff/forcing them to upgrade, or making applications which aren't as impressive as they could be."

    Palm wishes they could have this "problem'". Palm has every little money in the bank and is in league with Sprint which is the most dubious cell company in existence right now. They make AT&T look good. They have terrible dev tools, have already pissed of a lot of developers, and you can only write web apps for the Pre. 8GB of ram and the terrible keyboard are showstoppers for me.
    Developing for iPhone or Pre is a quite easy decision. iPhone has the mass of the marketplace and a real SDK. Palm has neither and may never have.

    "While Leopard had nearly as shaky/buggy a start as Vista (though 99.9% of Mac users won't admit it), Leopard has reportedly morphed into a very stable and serviceable system."

    You must have dreamed this. Leopard had nowhere near the shaky start of Vista. I used both Leopard and Vista pre-beta and RC for many months. Its really amazing the things people say with no idea what they are talking about.

    "The greatest weakness of the iPhone is the controls."

    Why, because it doesn't have the kind of controls you are used to? Developers have done amazing things with multi-touch and the accelerometer.

    "The average phone user doesn't care much about games and game controls"

    I don't know what you consider average. Apple does in fact care about games and the iPhone and plenty of iPhone users buy them. Enough for a very robust marketplace. Check the numbers.

    I'm interested to hear about the radios and if we can expect better, stronger, clearer signals.
    Reply
  • michaely - Wednesday, June 10, 2009 - link

    2 cents? All you gave was a penny. I laughed at your post so much. Could you be anymore of a fanboy? You purposely go out of your way to diss Microsoft and Palm, but completely ignore the points you quoted. Snow Leopard is Intel only (READ: no G4/G5). Where is the support? You are talking about the past, we are in the present and looking to the future.

    The sad thing is you probably don't even own a iPhone. You are a sad excuse of a fanboy. PERIOD.
    Reply
  • jasaero - Wednesday, June 10, 2009 - link

    Anand,

    You hint ARM and Imagination Tech own the mobile procesing space here, but wondering if you have any write ups in the works that compare the PowerVR based intgrated GPU offerings to th also popular Qualcomm ATI based cores? Also in January Qualcomm purchased the ATI handheld unit and got rights to all related IP along with some staff to keep said mobile ATI core competitive.

    To me this could mean an advantage for qualcomm 's Snapdragon if PowerVR's cores aren't a lot better than Qualcomms ATI or PowerVR offering VERY affordable licencing? I know this goes outside the iPhone 3Gs review a bit, but it will have probably ALOT of snapdragon competitors soon! And some of these Snapdragon competitors could show up with even more mature Android.
    Reply
  • jasaero - Wednesday, June 10, 2009 - link

    Here is some good info on the unique ARMv7 ISA based Scorpion core used in snapdragon! I for the life of me can't find info on the ATI handheld core that Qualcomm uses and now owns?? They seem to have invested more in the ARMv7 ISA than their more or less standard Cortex competition. Of particular interest is the lower power and double width SIMD unit.

    Now who can find info on this ATI core?
    Reply

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