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Data-oriented design

DOD is a programing style that focus on the fact that the code in the end will run on some real hardware. While other paradigms try create a easy mental model for the programmer DOD aim to make it easy for the hardware to read and write the data. The problem that normally exist are as follows.  
  • The CPU needs to wait for memory access if things are not in the memory cache. The faster a CPU get relative to the memory the more CPU cycles is wasted on waiting. That can apply to both waiting for code instructions to be loaded or data to be loaded.  
  • When multi threading the CPU needs to wait for other resources to get unlocked so it can use them.
The goal is to get the maximum amount of flow of data without any stalls waiting for anything. This is done as follows.
  • Focus on data. How is it read, transformed and written.
  • Usage pattern
    • Activity - How often field is accessed. Often is hot and less often is cold.
    • Correlation - How often fields are used together.
  • Split data into hot and cold. A struct with the hot data that have a pointer to the cold data. All the hot data can then be one array and the cold another. If pure arrays and index are used on both one can skip the pointers.
  • Improve locality by keeping data that is accessed together close to each other.
  • Watch compiler padding so data structures do not bloat with padding.
  • Linear data is best.
  • The source data and the native data does not need to be the same. 
  • Linearize data at runtime.

Reference



Explaining Data Oriented Design - 2015


Data Oriented Design : Starting Up - 2013
Adventures in data-oriented design - 2013
Part 4: Skinning it to 11
Part 3c: External References
Part 3b: Internal References
Part 3a: Ownership
Part 2: Hierarchical data
Part 1: Mesh data
Behind the Mirror - Adding Reflection to C++ - 2011
Culling the Battlefield Data Oriented Design in Practice - 2011
Introduction to Data Oriented Design - 2010
Data oriented design links - 2010
Musings on Data-Oriented Design - 2010
Is Data-Oriented Design a Paradigm? - 2010
Data Oriented Luddites - 2010
Data-Oriented Design (Or Why You Might Be Shooting Yourself in The Foot With OOP) - 2009
Data Locality - 2009
Data Alignment - 2009. Part I & Part II.
A Templated C++ Attribute Library for Object Persistence and Export - 2008
Data-Oriented Design
Data-Oriented Design book
Practical Examples in Data Oriented Design
Memory Optimization
Adventures in data-oriented design – Part 3a: Ownership- 2013

Data Oriented Design : Starting Up - 2013
https://www.randygaul.net/2013/05/05/data-oriented-design-starting-up/

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