Eight million pixels and counting: improving texture atlas allocation in Firefox (2021)

The article discusses the improvement of texture atlas allocation in WebRender, focusing on the development of the guillotiere crate and its impact on texture memory usage in WebRender/Firefox. Texture atlas allocation is crucial for efficiently submitting work to the GPU by grouping drawing primitives into batches. The guillotine algorithm was initially used but was replaced due to fragmentation issues. A new guillotine allocator was developed to address fragmentation efficiently. Visualizing the atlas using SVG format was found to be a powerful tool for debugging and tuning the algorithm. The article also touches on the simplicity and effectiveness of Rust programming language and ecosystem in developing and testing the guillotiere crate. Furthermore, the importance of fuzzing using Cargo fuzz for testing and improving code robustness is highlighted. The article concludes with the exploration of further improvements in draw call batching and texture upload overhead to enhance performance on low-end Intel GPUs. The balancing act between packing more items into fewer textures and cache management is discussed, emphasizing the benefits of better texture atlases in reducing driver overhead and improving performance.