COOL Chips IV A High Performance 3D Graphics Raste rizer with Effective Memory Structure Woo-Chan Park, Kil-Whan Lee*, Seung-Gi Lee, Moon-H ee Choi, Won-Jong Lee, Cheol-Ho Jeong, Byung-Uck Kim, Woo-N am Jung, Il-San Kim, Won-Ho Chun, Won-Suk Kim, Tack-Don Han , Moon-Key Lee, Sung-Bong Yang, and Shin-Dug Kim Media System Lab. Yonsei University Seoul, Korea E-mail : [email protected]
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COOL Chips IV A High Performance 3D Graphics Rasterizer with Effective Memory Structure Woo-Chan Park, Kil-Whan Lee*, Seung-Gi Lee, Moon-Hee Choi, Won-Jong.
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COOL Chips IV
A High Performance 3D Graphics Rasterizer with Effective Memory Structure
Woo-Chan Park, Kil-Whan Lee*, Seung-Gi Lee, Moon-Hee Choi,
Won-Jong Lee, Cheol-Ho Jeong, Byung-Uck Kim, Woo-Nam Jung,
Il-San Kim, Won-Ho Chun, Won-Suk Kim, Tack-Don Han,
High Performance 3D Graphics Rasterizer with Effective Memory Str
ucture (David Rasterizer)
COOL Chips IV
- - 1111 - -
Architectural features of David rasterizer
Performing z-test pipeline before TBE(Texture, Bump, and Environment) mapping completion Saving memory bandwidth Solve the incosistency problem with tagging schem
e for pixel cache Texture cache sharing with BE(Bump and Envi
ronment) mapping Efficient structure
COOL Chips IV
- - 1212 - -
Rasterizer model : Neon, S3
Texture cache
Texture read / filter
Texture blend
Pixel information
memory
Z read
Z test
Z write
Alpha test
Destination read
Alpha blend
Destination write
memory
Texture cache
Z read
Z test
Z write
Texture read / filter
Texture blend
Alpha test
Destination read
Alpha blend
Destination write
Pixel information
Neon S3
COOL Chips IV
- - 1313 - -
David Rasterizer
memory
Texture cache
Tag test and Z read
Z test
Texture read / filter
Texture blend
Alpha test
Destination read
Alpha blend
Destination write
Pixel information
Pixel cache
Pixel cache
Tag update and Z write
wid
e se
par
ate
COOL Chips IV
- - 1414 - -
Architecture Comparison Neon
When is texture mapping performed?
before Z test
OpenGL semantics for perfectly transparent texture
Support
S3
after Z test
Not support
David
after Z test
Support
Advantages• Support OpenGL semantics
• No wasting bandwidth No fetching texture data that are obscured
• Simple scheme• No wasting bandwidth No fetching texture data that are obscured• Support OpenGL semantics
Disadvantages • Wasting bandwidth• Unable to support OpenGL semantics
• Wide separation Inconsistency problemSolve it using additional flag bits in a pixel cache
COOL Chips IV
- - 1515 - -
Texture Cache Sharing
Texture Mapping #2Texture Mapping #1 Cache DRAM
Bump Mapping
Environment Mapping
Current 3D Architecture
Texture Mapping #1
DRAM
David 3D Architecture
Shared H/W
Bump Mapping
Texture Mapping #2
Shared H/W
Environment Mapping
SharedCache
DRAM
DRAM
Current Architecture David Architecture
Mapping Hardware
Cache Size
# of Read Port in Cache
Independent H/WShared H/W
Reduce H/W cost (about 30%)
Same Same
2 2
Throughput 1 CycleTexture Mapping : 1 Cycle
BE Mapping : 2 Cycles (infrequent operations)
Features BE Mapping : DRAM AccessBE Mapping : Cache Access
Remove Pipeline Stalls due to DRAM Access
COOL Chips IV
Performance Analysis
COOL Chips IV
- - 1717 - -
Z Depth Complexity, # of Z Test Fails
Environments for Performance Evaluation
Model DataModel Data
Mesa Library CallMesa Library Call
Miss Ratio, Performance
Rasterizer
OpenGL format
Setup pipelineSetup pipeline
Edge work pipelineEdge work pipeline
Span processingSpan processing
MC for frame buffer accessMC for frame buffer access