Exclusive: ASUS Debuts AGEIA PhysX Hardware
by Derek Wilson on May 5, 2006 3:00 AM EST- Posted in
- GPUs
AGEIA PhysX Technology and GPU Hardware
First off, here is the low down on the hardware as we know it. AGEIA, being the first and only consumer-oriented physics processor designer right now, has not given us as much in-depth technical detail as other hardware designers. We certainly understand the need to protect intellectual property, especially at this stage in the game, but this is what we know.PhysX Hardware:
125 Million transistors
130nm manufacturing process
128MB 733MHz Data Rate GDDR3 RAM
128-bit memory bus interface
20 giga-instructions per second
2 Tb/sec internal memory bandwidth
"Dozens" of fully independent cores
There are quite a few things to note about this architecture. Even without knowing all the ins and outs, it is quite obvious that this chip will be a force to be reckoned with in the physics realm. A graphics card, even with a 512-bit internal bus running at core speed, has less than 350 Gb/sec internal bandwidth. There are also lots of restrictions on the way data moves around in a GPU. For instance, there is no way for a pixel shader to read a value, change it, and write it back to the same spot in local RAM. There are ways to deal with this when tackling physics, but making highly efficient use of nearly 6 times the internal bandwidth for the task at hand is a huge plus. CPUs aren't able to touch this type of internal bandwidth either. (Of course, we're talking about internal theoretical bandwidth, but the best we can do for now is relay what AGEIA has told us.)
Physics, as we noted in last years article, generally presents itself in sets of highly dependant small problems. Graphics has become sets of highly independent mathematically intense problems. It's not that GPUs can't be used to solve these problems where the input to one pixel is the output of another (performing multiple passes and making use of render-to-texture functionality is one obvious solution); it's just that much of the power of a GPU is mostly wasted when attempting to solve this type of problem. Making use of a great deal of independent processing units makes sense as well. In a GPU's SIMD architecture, pixel pipelines execute the same instructions on many different pixels. In physics, it is much more often the case that different things need to be done to every physical object in a scene, and it makes much more sense to attack the problem with a proper solution.
To be fair, NVIDIA and ATI are not arguing that they can compete with the physics processing power AGEIA is able to offer in the PhysX chip. The main selling points of physics on the GPU is that everyone who plays games (and would want a physics card) already has a graphics card. Solutions like Havok FX which use SM3.0 to implement physics calculations on the GPU are good ways to augment existing physics engines. These types of solutions will add a little more punch to what developers can do. This won't create a revolution, but it will get game developers to look harder at physics in the future, and that is a good thing. We have yet to see Havok FX or a competing solution in action, so we can't go into any detail on what to expect. However, it is obvious that a multi-GPU platform will be able to benefit from physics engines that make use of GPUs: there are plenty of cases where games are not able to take 100% advantage of both GPUs. In single GPU cases, there could still be a benefit, but the more graphically intensive a scene, the less room there is for the GPU to worry about anything else. We are certainly seeing titles coming out like Oblivion which are able to bring everything we throw at it to a crawl, so balance will certainly be an issue for Havok FX and similar solutions.
DirectX 10 will absolutely benefit AGEIA, NVIDIA, and ATI. For physics on GPU implementations, DX10 will decrease overhead significantly. State changes will be more efficient, and many more objects will be able to be sent to the GPU for processing every frame. This will obviously make it easier for GPUs to handle doing things other than graphics more efficiently. A little less obviously, PhysX hardware accelerated games will also benefit from a graphics standpoint. With the possibility for games to support orders of magnitude more rigid body objects under PhysX, overhead can become an issue when batching these objects to the GPU for rendering. This is a hard thing for us to test for explicitly, but it is easy to understand why it will be a problem when we have developers already complaining about the overhead issue.
While we know the PhysX part can handle 20 GIPS, this measure is likely simple independent instructions. We would really like to get a better idea of how much actual "work" this part can handle, but for now we'll have to settle for this ambiguous number and some real world performance. Let's take a look a the ASUS card and then take a look at the numbers.
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DrZoidberg - Sunday, May 7, 2006 - link
Yes dual core CPU's aren't being properly utilised by games. Only handful of games like COD2, Quake4 etc.. have big improvements with the dual core CPU patches. I would rather game companies spend time trying to utilise dual core so the 2nd core gets to do alot of physics work, rather then sitting mostly idle. Plus the cost of AGEIA card is too high. Already I'm having trouble justifying buying a 7900gt or x1900 when i have a decent graphics card, cant upgrade graphics every year. $300 for physics card that only handful of games support is too much. And the AT benchies dont show alot of improvement.Walter Williams - Friday, May 5, 2006 - link
We are starting to see multithreaded games that basically do this.However, it is very difficult and time consuming to make a game multi-threaded, hence why not many games are this way.
Hypernova - Friday, May 5, 2006 - link
Physx API claims to be multy core compatiable, what will happen is probably is the the API and engine will load balance the calculation between any available resources which is either the PPU, CPU or better yet both.JarredWalton - Friday, May 5, 2006 - link
Isn't it difficult to reprogram a game to make use of the hardware accelerated physics as well? If the GRAW tests perform poorly because the support is "tacked on", wouldn't that suggest that doing PhysX properly is at least somewhat difficult? Given that PhysX has a software and hardware solution, I really want to be able to flip a switch and watch the performance of the same calculations running off the CPU. Also, if their PhysX API can be programmed to take advantage of multiple threads on the PhysX card (we don't have low level details, so who knows?), it ought to be able to multithred calculations on SMP systems as well.I'd like to see the CellFactor people add the option of *trying* to run everything without the PhysX card. Give us an apples-to-aplles comparison. Until we can see that sort of comparison, we're basically in the dark, and things can be hidden quite easily in the dark....
Walter Williams - Friday, May 5, 2006 - link
PPU support is simply achieved by using the Novadex physics engine or any game engine that uses the Novadex engine (ex/ Unreal Engine 3.0). The developers of GRAW decided to take a non-basic approach to adding PPU support, adding additional graphical effects for users of the PPU - this is similar to how Far Cry 64 advertises better graphics b/c it is 64bits as an advertising gimmick. GRAW seems to have issues in general and is not a very reliable test.At quakecon '05, I had the opportunity to listen to the CEO of Ageia speakd and then meet with Ageia representatives. They had a test system that was an Athlon64 X2, a top of the line video card, and a PPU. The demo that I was able to play was what looked to be an early version of the Unreal Engine 3.0 (maybe Huxley?) and during the demo they could turn on and off PPU support. Everytime we switched between the two, we would take notice of the CPU usage meter and of the FPS and there was a huge difference.
It will be really interesting to see what happens when Microsoft releases their physics API (think DirectX but for physics) - this should make everyones lives better.
johnsonx - Friday, May 5, 2006 - link
Having downloaded and viewed the videos, my reaction is "so what?". I guess the physx sequence has a bit more crap flying around, but it's also quite alot slower (slower probably than just letting the CPU process the extra crap). It seems obvious that this game doesn't make proper use of the physx card, as I can't otherwise imagine that Aegia would have wasted so much time and money on it.DerekWilson - Friday, May 5, 2006 - link
We'd really love to test that, but it is quite impossible to verify right now.
Walter Williams - Friday, May 5, 2006 - link
Have you seen the CellFactor videos yet?Spoonbender - Friday, May 5, 2006 - link
Well, looking at the videos, I know what I prefer. The framerate hit with physx is definitely too noticeable. I'm curious to see how this turns out in other games, and with driver revisions and newer versions of the hardware (and probably pci-e would be a good idea as well)In any case, I read somewhere they weren't expecting these cards to evolve as fast as GPU's. Rather, it'd have a life cycle about the same as for soundcards. That seemed a bit encouraging to me. Having to fork out $300+ for yet another card every year or two didn't sound too attractive. But if I just have to buy it once, I guess it might catch on.
tk109 - Friday, May 5, 2006 - link
With quad cores around the corner this really isn't looking to promising.