Designing Network Design Spaces
Paper · 2020 · Ilija Radosavovic, Raj Prateek Kosaraju, Ross Girshick et al.
Summary
Neural architecture search usually returns one network tuned to one setting, such as a specific hardware target. That output says little about why the network works or how to adapt it elsewhere. The authors instead design whole design spaces, meaning parametrized families of architectures. They judge each space by sampling and training many models and examining the resulting error distribution, building on the methodology of Radosavovic et al. [21].
They start from a loosely constrained space called AnyNet, where stage widths and depths vary freely. A sequence of human-guided refinement steps then produces simpler spaces that keep or improve population quality. The result is RegNet, a low-dimensional space where stage widths and depths follow a quantized linear rule. The space is designed cheaply on ImageNet (400MF models, 10 epochs) and then shown to hold for larger compute, longer schedules and other block types.
RegNet models clearly beat ResNe(X)t and do well in the mobile regime. They also outperform EfficientNet at comparable flops and training setups while running up to 5× faster on GPUs. The work matters because it yields transferable design rules rather than one isolated model.
Key points
- The design process goes from AnyNet to RegNet. Space quality is measured with the error empirical distribution function (EDF) over sampled models, for example n = 500 models in the 400MF, 10-epoch regime.
- RegNet's main finding is that good networks have stage widths and depths explained by a quantized linear function of the stage/block index.
- Some findings go against common practice. The best models have roughly 20 blocks regardless of compute regime, and they use neither a bottleneck nor an inverted bottleneck.
- Training settings were checked on populations of models. lr = 0.1 and wd = 5·10⁻⁵ proved stable across flop regimes and schedule lengths. Among the block types tested (X, R, V, VR), the X block performed best, and residual connections did not help the V block.
- Training tricks strongly affect EfficientNet-B0 results: without them, error is about 2% worse. Generalization was also tested on ImageNetV2, and code and models are released in pycls.
Interesting ideas
- I1. Evaluate distributions, not single winners. Sample and train many cheap models from a configuration space and compare error distributions, which removes much of the luck of a single run. The same idea could be used to compare tokenizers, data mixes or model variants in NLP.
- I2. Refine the space step by step. Each step adds a constraint, such as shared parameters or monotone widths, and keeps it only if the population does not get worse. The result is an interpretable rule rather than a black-box search outcome.
- I3. Explore in a low-cost regime, then confirm at scale. Run the exploration at small compute and few epochs, then check that the conclusions hold for bigger models and longer training. This makes broad sweeps affordable on limited budgets.
- I4. Bootstrap confidence ranges for good settings. An empirical bootstrap over sampled models gives a likely range for the best value of each parameter, such as depth, width, learning rate or weight decay. This approach can be applied to hyperparameter studies in any domain.
- I5. Control the training setup in comparisons. Retrain baselines under the same recipe before comparing. The EfficientNet-B0 gap shows that training enhancements alone can account for differences that might otherwise be credited to the architecture.
Institutions
Fields, topics and concepts
📚 Shelves 3The field of science this work belongs to (OpenAlex fields).Computer Science · 18,614 worksArtificial Intelligence · 17,965 worksComputer Vision and Pattern Recognition · 3,486 works
Cite
Cite as Ilija Radosavovic, Raj Prateek Kosaraju, Ross Girshick, Kaiming He and Piotr Dollar. 2020. Designing Network Design Spaces. arXiv:2003.13678.
@misc{radosavovic2020designing,
title = {{Designing Network Design Spaces}},
author = {Ilija Radosavovic, Raj Prateek Kosaraju, Ross Girshick, Kaiming He and Piotr Dollar},
year = {2020},
doi = {10.48550/arxiv.2003.13678},
eprint = {2003.13678},
archivePrefix = {arXiv},
url = {https://doi.org/10.48550/arxiv.2003.13678}
}References
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