Timothy John Purcell

A Survey of General-Purpose Computation on Graphics Hardware

The rapid increase in the performance of graphics hardware, coupled with recent improvements in its programmability, have made graphics hardware a compelling platform for computationally demanding tasks in a wide variety of application domains. In this report, we describe, summarize, and analyze the latest research in mapping general‐purpose computation to graphics hardware.

Ray tracing on programmable graphics hardware

Recently a breakthrough has occurred in graphics hardware: fixed function pipelines have been replaced with programmable vertex and fragment processors. In the near future, the graphics pipeline is likely to evolve into a general programmable stream processor capable of more than simply feed-forward triangle rendering.In this paper, we evaluate these trends in programmability of the graphics pipeline and explain how ray tracing can be mapped to graphics hardware. Using our simulator, we analyze the performance of a ray casting implementation on next generation programmable graphics hardware. In addition, we compare the performance difference between non-branching programmable hardware using a multipass implementation and an architecture that supports branching. We also show how this approach is applicable to other ray tracing algorithms such as Whitted ray tracing, path tracing, and hybrid rendering algorithms. Finally, we demonstrate that ray tracing on graphics hardware could prove to be faster than CPU based implementations as well as competitive with traditional hardware accelerated feed-forward triangle rendering.

GPGPU: general purpose computation on graphics hardware

The graphics processor (GPU) on todays commodity video cards has evolved into an extremely powerful and flexible processor. The latest graphics architectures provide tremendous memory bandwidth and computational horsepower, with fully programmable vertex and pixel processing units that support vector operations up to full IEEE floating point precision. High level languages have emerged for graphics hardware, making this computational power accessible. Architecturally, GPUs are highly parallel streaming processors optimized for vector operations, with both MIMD (vertex) and SIMD (pixel) pipelines. Not surprisingly, these processors are capable of general-purpose computation beyond the graphics applications for which they were designed. Researchers have found that exploiting the GPU can accelerate some problems by over an order of magnitude over the CPU.However, significant barriers still exist for the developer who wishes to use the inexpensive power of commodity graphics hardware, whether for in-game simulation of physics of for conventional computational science. These chips are designed for and driven by video game development; the programming model is unusual, the programming environment is tightly constrained, and the underlying architectures are largely secret. The GPU developer must be an expert in computer graphics and its computational idioms to make effective use of the hardware, and still pitfalls abound. This course provides a detailed introduction to general purpose computation on graphics hardware (GPGPU). We emphasize core computational building blocks, ranging from linear algebra to database queries, and review the tools, perils, and tricks of the trade in GPU programming. Finally we present some interesting and important case studies on general-purpose applications of graphics hardware.The course presenters are experts on general-purpose GPU computation from academia and industry, and have presented papers and tutorials on the topic at SIGGRAPH, Graphics Hardware, Game Developers Conference, and elsewhere.

Debugging tools

Programming Soap Box • Successful programming systems require at least three ‘tools’ • Compiler •Cg, HLSL, GLSL, RTSL, Brook... • Debugger • Profiler Debugging State of the Art • ‘printf’ debugging • MOV suspect register to output •Comment out anything else writing to output •Scale and bias as needed • Recompile • Display/readback frame buffer • Check values • Repeat until error is (hopefully) found