A summary of gpgpu

1. 2010/2/25
1
GPGPU
Ked
Result
Computation of Normal Vector
Image resolution: 640 x 480
CPU: 625 clock time
GPU: 125 clock time
Result
Computation of Normal Vector
Image resolution: 1280 x 1024
CPU: 2500 clock time
GPU: 172 clock time
OK, What is GPU
 A graphics accelerator incorporates custom
microchips which contain special mathematical
operations commonly used in graphics rendering.
GPGPU
• General purpose computing on GPU
 GPGPU
 GPGP
 GP2
(boring RD -.-||)‫‏‬
hi, I am R2-D2
Why faster

2. 2010/2/25
2
Why faster Why faster
 CPU GPU
General purpose Specialized hardware
Serial execution Parallel execution
Minimum latency Maximum throughput
Development tools:
Focus on GPGPU
 CUDA:
 Compute Unified Device Architecture
 Developed by NVIDIA
 C like language
 Full developing environment
 Compiler
 Debugger
 Math libraries
Development tools:
Focus on GPGPU
 Advantage:
 Shared memory amongst threads
 16k
 Faster downloads and readbacks to and from GPU
 Full support for integer and bitwise operations
Development tools:
Shader programming
 ARB low-level assembly language
 OpenGL shading language
 Cg programming language
 DirectX high-level shader language
Development tools:
Shader programming

3. 2010/2/25
3
Development tools:
Shader programming
 Developing tools of GLSL:
Pipeline of GPU processing
Shader programming
Vertex shader
Fragment shader
Geometry shader
RenderMan shading language
 Developed by Pixar has uncompromising image
quality as its fundamental goal
 Light shader
 Displacement shader
 Surface shader
 Volume shader
 Imager shader
Vertex shader Fragment shader

4. 2010/2/25
4
Streaming of fragment shader
 Stream processing is a computer programming paradigm,
related to SIMD, that allows some applications to more
easily exploit a limited form of parallel processing. Such
applications can use multiple computational units, such
as the floating point units on a GPU, without explicitly
managing allocation, synchronization, or communication
among those units.
Branch of fragment shader
Conception of GPGPU
 Textures => Computing arrays
 Vertex Coordinates => Computational range
 Fragment programs => Computation
 Read from framebuffer => Get result
Case study:
Computation of normal vector
 Normal(V0) =
[ normal(F401) +
normal(F102) +
normal(F203) +
normal(F304) ] / 4
 Normal(F102) =
cross(v1v0, v2v0)‫‏‬
Prepare:
Choose graphic card
Prepare:
Test the graphic card
need

5. 2010/2/25
5
Use GLSL in BCB environment:
Call GLee library Other choice: GLew
Install shader:
Run-time building
Texture:
Computing array
Vertex coordinate:
Computational range
Fragment program:
Computation
Read from framebuffer:
Get result
FameBuffer Object is a better choice

6. 2010/2/25
6
Trivia:
Ghost in numerical computing
Review the result
Image resolution: 640 x 480
CPU: 625 clock time
GPU: 125 clock time
Image resolution: 1280 x 1024
CPU: 2500 clock time
GPU: 172 clock time
Reference
 GPU Gems 2
 OpenGL Shading Language
 OpenGL Programming Guide
 Dominik Göddeke
-- GPGPU::Basic Math Tutorial
(website)‫‏‬
 GPGPU: SIGGRAPH 2004 course
 Batch, batch, batch:
what does it really means
Thx.