AnandTech: The GPU Advances: ATI's Stream Processing & Folding@Home

In the continual progression of GPU technology, we've seen GPUs become increasingly useful at generalized tasks as they have added flexibility for game designers to implement more customized and more expansive graphical effects. What started out as a simple fixed-function rendering process, where texture and vertex data were fed into a GPU and pixels were pushed out, has evolved into a system where a great deal of processing takes place inside the GPU. The modern GPU can be used to store and manipulate data in ways that go far beyond just quickly figuring out what happens when multiple textures are mixed together.

What GPUs have evolved into today are devices that are increasingly similar to CPUs in their ability to do more things, while still specializing in only a subset of abilities. Starting with Shader Model 2.0 on cards like the Radeon 9700 and continuing with Shader Model 3.0 and today's latest cards, GPUs have become floating-point powerhouses that are able to do most floating-point calculations many times faster than a CPU, a necessity as 3D rendering is a very FP-intensive process. At the same time, we have seen GPUs add programming constructs like looping, branching, and other abilities previously only used on CPUs, but which are crucial to enable effective programmer use of the GPU resources . In short, today's GPUs have in many ways become extremely powerful floating-point processors that have been used for 3D rendering but little else.

Both ATI and NVIDIA have been looking to put the expanded capabilities of their GPUs to good use, with varying success. So far, the only types of programs that have effectively tapped this power other than applications and games requiring 3D rendering have also been video related, such as video decoders, encoders, and video effect processors. In short, the GPU has been underutilized, as there are many tasks that are floating-point hungry while not visual in nature, and these programs have not used the GPU to any large degree so far.

Meanwhile the academic world has been working on designing and utilizing custom-built floating-point hardware for years for their own research purposes. The class of hardware related to today's topic, stream processors, are extremely powerful floating-point processors able to process whole blocks of data at once, where CPUs carry out only a handful of numerical operations at a time. We've seen CPUs implement some stream processing with instruction sets like SSE and 3DNow!+, but these efforts still pale in comparison to what custom hardware has been able to do. This same progress was happening on GPUs, only in a different direction, and until recently GPUs remained untapped as anything other than a graphics tool.

Today's GPUs have evolved into their own class of stream processors, sharing much in common with the customized hardware of researchers, as a result of the 3D rendering process also being a streaming task. The key difference here however is that while GPU designers have cut a couple of corners where they don't need certain functionality for 3D rendering as compared to what a custom processor can do, by and large they have developed extremely fast stream processors that are just as fast as custom hardware but due to economies of scale are many, many times cheaper than a custom design.

It's here where ATI is looking for new ideas on what to run on their GPUs as part of their new stream computing initiative. The academic world is full of such ideas, chomping at the bit to run their experiments on more than a handful of customized hardware designs. One such application, and part of the star of today's announcement, is Folding@Home, a Stanford research project designed to simulate protein folding in order to unlock the secrets of diseases caused by flawed protein folding.