OOI-CI & IOOS-DMAC Intersection Project FY2010. OOI Overview.
Games are Up for DVFS Yan Gu Samarjit Chakraborty Wei Tsang Ooi Department of Computer Science...
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Transcript of Games are Up for DVFS Yan Gu Samarjit Chakraborty Wei Tsang Ooi Department of Computer Science...
Games are Up for DVFSGames are Up for DVFS
Yan Gu Samarjit Chakraborty Wei Tsang OoiDepartment of Computer Science
National University of Singapore
OutlineOutline
Introduction
Anatomy of a Game Engine
A First Cut: Reduce Frame Rates
The Case for DVFS
DVFS for Games
Conclusion
Goal of this work:
• Explore the possibility of using DVFS for interactive games
• Characterize the workload of game applications and use it to propose a DVFS scheme for games
IntroductionIntroduction
Popularity of interactive games on battery-powered portable devices (e.g. mobile phones, PDAs, PSP, etc.)
Voltage and frequency-scalable processors on portable devices
Can DVFS algorithms developed for video decoding applications be applied to games? no interaction in video decoding, no buffering in games
We show that: It is meaningful to use DVFS in the context of games frame structure in game applications can be exploited to
develop DVFS algorithms
Anatomy of a Game EngineAnatomy of a Game Engine
Event
Physics
DollisionDetection
Particle
AI
Rendering Display
Computing
A First Cut: Reduce Frame RatesA First Cut: Reduce Frame Rates
Current game design principles: higher frame rates imply the better game quality
Recent study on frame rates [Claypool et al. MMCN 2006] very high frame rates are not necessary, very low frame
rates impact the game quality severely
A First Cut: Reduce Frame RatesA First Cut: Reduce Frame Rates
Snapshots of animation [Davis et al. Eurographics 2003]time
A First Cut: Reduce Frame RatesA First Cut: Reduce Frame Rates
Current game design principles: higher frame rates imply the better game quality
Recent study on frame rates [Claypool et al. MMCN 2006] very high frame rates are not necessary, very low frame
rates impact the game quality severely
Obvious question: Can the CPU be run at a constant but lower frequency (to reduce the frame rate)?
A First Cut: Reduce Frame RatesA First Cut: Reduce Frame Rates
Current game design the higher frame rate, the better game quality
Recent study of frame rate very high frame rates are not necessary, very low frame
rates impact the game quality severely
Obvious question: Can the CPU be run at a constant but lower frequency (to reduce the frame rate)?
However, can DVFS algorithms developed for video decoding applications be applied to games? unpredictable workload because of the interaction in game no frame structure in video decoding
A First Cut: Reduce Frame RatesA First Cut: Reduce Frame Rates
Average system-level power consumption for different processor frequencies
The Case for DVFS Snapshots of Game MapsThe Case for DVFS Snapshots of Game Maps
“Outer Base” game map in Quake II “Installation” game map in Quake II
Game workload includes computational workload and rendering workload correspondence with the complexity of the scene
Software renderer performs geometry, rasterization and texture processing on CPU portable devices without graphics accelerator
Software rasterization workload is the workload of rasterizing objects on the screen correspondence with the complexity of the scene
The Case for DVFS Workload in GamesThe Case for DVFS Workload in Games
The Case for DVFS Workload in GamesThe Case for DVFS Workload in Games
Game workload
Computational workload
Rendering workload
Other workload
Rasterization workload
The Case for DVFS Workload in GamesThe Case for DVFS Workload in Games
Game workload
Computational workload
Rendering workload
Other workload
Rasterization workload
Scene complexity
The Case for DVFSWorkload as a Function of Scene ComplexityThe Case for DVFSWorkload as a Function of Scene Complexity
The Case for DVFSWorkload CharacterizationThe Case for DVFSWorkload Characterization
Each frame constitutes of the following objects: brush model – construct the “world space” Alias model – model characters like monsters, soldiers
and weapons texture – give the appearance of the brush model light map – generate “lighting” effect particles – model small debris from gun shots ...
The Case for DVFSWorkload CharacterizationThe Case for DVFSWorkload Characterization
Each frame constitutes of the following objects: brush model – construct the “world space” Alias model – model characters like monsters, soldiers
and weapons texture – give the appearance of the brush model light map – generate “lighting” effect particles – model small debris from gun shots ...
Computing workload of a frame:
• Determine workload incurred in rasterizing each object offline
• Determine the number of occurrences of each object online
The Case for DVFSBrush ModelThe Case for DVFSBrush Model
Brush model parameter: the number of polygons constituting
the brush model
The Case for DVFSAlias ModelThe Case for DVFSAlias Model
Alias model parameters:
the number of pixels of triangles opaque or alpha blending mode of skin texture
The Case for DVFSTexture, light map and particlesThe Case for DVFSTexture, light map and particles
Texture parameter: the number of surfaces
Light map parameter: the number of surfaces
Particles parameters: the number of pixels of 3D points
Total rasterization workload = #cycles for brush X #brush models
+ #cycles for Alias X #Alias models
+ #cycles for texture X #textures
+ #cycles for light map X #light maps
+ #cycles for particle X #particles
DVFS for GamesDVFS for Games
Poll player’s message
Compute visible objects
Render the frame
Obtain workload parameters of each
object
Online predict workload
Compute required CPU frequency
Scale to required CPU frequency
Game loop
DVFS for GamesDVFS for Games
Data structures to maintain the correlation between the workload parameters and the corresponding rasterization workload of each type of object
Linear regression model to find the fitting functions between the workload parameters and the corresponding rasterization workload for each type of object
Initial experiments show significant system-level power saving with our proposed framework
ConclusionConclusion
Explore the possibility of using DVFS for interactive games
Propose the workload characterization for games
Outline DVFS algorithms with our proposed workload characterization