Lucid's Multi-GPU Wonder: More Information on the Hydra 100
by Derek Wilson on August 22, 2008 4:00 PM EST- Posted in
- GPUs
What Does This Thing Actually Do?From a high level, Lucid's technology intercepts DirectX or OpenGL API calls, analyzes them, organizes them into distinct tasks, and based on the analysis combined with the historical performance of various cards handling of previous frames' workload, it evenly distributes the tasks across all the GPUs in the system.
After the workload is distributed, the buffers are read back to the Hydra chip and composited before the final scene is sent to the proper graphics card for display. Looking a bit deeper, here is a block diagram of the process itself from Lucid's whitepaper.
The current implementation can take x16 PCIe in and can switch it to either 2x x16 PCIe channels or up to 4x x16 PCIe channels. This gives it support for 1 to 4 cards depending on how the motherboard or graphics card handles things. They do have the flexibility to scale down to x8 in and 2x x8 out, making lower cost motherboards feasible as well. Future products may support more graphics cards and more PCIe lanes, but right now 4 is what makes sense. Lucid says the hardware can scale up to any number of cards with linear performance improvement.
Some of the implications of this process are that if any graphics card in the system has other work being done on it (say maybe physics or video or something), the load will be dynamically balanced and you'll still be able to squeeze as much juice out of all the hardware in your system as possible. Pretty cool huh? If it works as advertised that is.
The demo we saw behind closed doors with Lucid did show a video playing on one 9800 GT while the combination of it and one other 9800 GT worked together to run Crysis DX9 with the highest possible settings at 40-60 fps (in game) with a resolution of 1920x1200. Since I've not tested Crysis DX9 mode on 9800 GT I have no idea how good this is, but it at least sounds nice.
Since Lucid is analyzing the data, they can even do things like not draw hidden "tasks" (if an entire object is occluded, rather than send it to a graphics card, it just doesn't send it down). I asked about dependent texturing and shader modification of depth, and apparently they also build something like a dependency graph and if something modified affects something else they are able to adjust that on the fly as well.
In theory, tracking and adjusting to dependencies on the fly will completely avoid the issues that keep NVIDIA and AMD from running AFR in all games. And they even claim that this can help give you higher than linear scaling when using their hardware with more than one card.
We asked what the latency of their implementation is, and they said it is negligible. Of course, that's not a real answer, especially for guys like us who want to know the details so we can understand what's going on better. We don't just want to see the end result, we want to know how we get there. Playing Crysis didn't feel laggy, but there is no way this solution doesn't introduce processing time.
An explanation for this is the fact that the Hydra software can keep requesting and queuing up tasks beyond what graphics cards could do, so that the CPU is able to keep going and send more graphics API calls than it would normally. This seems like it would introduce more lag to us, but they assured us that the opposite is true. If the Hydra engine speeds things up over all, that's great. But it certainly takes some time to do its processing and we'd love to know what it is.
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GTVic - Friday, August 22, 2008 - link
This company is not making graphics cards, and to use their product you have to buy more graphics cards. Seems like a win-win situation. AMD and nVidia can dump development on crossfire/sli and sales go up.DerekWilson - Saturday, August 23, 2008 - link
if nvidia dumps sli then there is zero reason for them to be in the chipset business right now.they are no longer needed for AMD because AMD isn't making horrid chipsets anymore. they aren't needed for Intel because Intel builds awesome motherboards.
the only value add nvidia has on the platform side is sli. period.
they do not want to see it become irrelevant.
shin0bi272 - Friday, August 22, 2008 - link
This is a gamers dream (assuming it works as advertised) and a video card makers nightmare.If they really wanted to demo it they probably should have been running 2 systems side by side, one with 1 card and one with the hydra running 2 cards to show the actual difference. Maybe also not run crysis since crysis has issues with framerate on any system... maybe run 3dmark vantage (I know its not an actual game but its a standardized program) especially if its transparent to the game and hardware.
Personally if AMD and Nvidia have a problem with this technology and they disable it (or force me to so I can play any game) there's still Intel's Larabee on the horizon and I'm sure Intel wouldnt disable the hydra so Id just dump AMD and Nvidia all together to get linear performance increases (again assuming it works).
On top of that AMD and Nvidia have their own performance issues and competition to worry about especially now that the physx war has begun (AMD hooking up with havoc and Nvidia buying Ageia).
I think both AMD and Nvidia should embrace this technology and abandon their approaches so that they can concentrate more on individual card performance. Since the performance gains with both SLi and crossfire arent linear and this promises to be. Even if its not 100% linear but its a 90% speed gain thats still better than either of the other solutions.
The game designers would also love this technology because they wouldnt have to worry about enabling SLi or crossfire in their games they could concentrate on the actual game play and making the game fun and cool looking.
shin0bi272 - Friday, August 22, 2008 - link
Oh also I forgot to mention that the article did say that you would have to have 2 of the same brand of card so youd still be locked into one manufacturer. So its not like youd be mixing an nvidia 280 with an amd 4870x2. So amd and nvidia really shouldnt have a huge problem with it.Diesel Donkey - Friday, August 22, 2008 - link
That is false. The article states that any combination of two, three, or four cards from either AMD or Nvidia can be used. That's one reason this technology would be so amazing if it actually works and is implemented successfully.The Preacher - Saturday, August 23, 2008 - link
I don't think you would like some portions of the same screen rendered by nvidia and others by ATI since they will look different and could create some discontinuities in the final image.DerekWilson - Saturday, August 23, 2008 - link
they try really hard to render nearly the same image ... but if you played half-life 2 then this would be an issue.also, to enable this they would have to wait for vista to allow it (i think) ... thing is they are building a wddm driver ... so ... nvidia's display driver wouldn't be "running" either? I don't really know how that works.
jordanclock - Friday, August 22, 2008 - link
No, he is right. You can't have an nVidia card with an AMD card. As it stands, Windows won't allow two graphics drivers to run in 3D mode. This was addressed in the first article featuring this technology.prophet001 - Friday, August 22, 2008 - link
how amazing would this be. nice article with what you were given.MrHanson - Friday, August 22, 2008 - link
I thing having a separete box with it's own power supply(s) is ideal for something like this. That way if you want to add 2 or more gpu's to your hydra system, you don't have to rip apart your computer and put in a different motherboard and power supply. I imagine this system will probably come with it's own mainboard and power supply with several separate pcie x16 slots for scalablity. Also if you were to upgrade your motherboard and cpu, you don't have to worry about getting a motherboard with enough pcie x16 slots or if the motherboard supports the hydra engine. Any ol' motherboard with one pci express slot will do.