# KDEformer: Accelerating Transformers via Kernel Density Estimation

arXiv: https://arxiv.org/abs/2302.02451 · HTML: https://mlsanity.com/paper/2302.02451/

## Key facts

- Cited by 58 papers in the map (data through 14 Oct 2026).
- Builds on 26 of its 39 references that are in the map.
- First posted on arXiv 5 Feb 2023.

## Builds on (most cited first, 26 of 26)

- [Attention Is All You Need](https://mlsanity.com/paper/1706.03762/) (2017)
- [BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding](https://mlsanity.com/paper/1810.04805/) (2018)
- [Language Models are Few-Shot Learners](https://mlsanity.com/paper/2005.14165/) (2020)
- [An Image is Worth 16x16 Words: Transformers for Image Recognition at Scale](https://mlsanity.com/paper/2010.11929/) (2020)
- [Exploring the Limits of Transfer Learning with a Unified Text-to-Text Transformer](https://mlsanity.com/paper/1910.10683/) (2019)
- [End-to-End Object Detection with Transformers](https://mlsanity.com/paper/2005.12872/) (2020)
- [Improved Techniques for Training GANs](https://mlsanity.com/paper/1606.03498/) (2016)
- [XLNet: Generalized Autoregressive Pretraining for Language Understanding](https://mlsanity.com/paper/1906.08237/) (2019)
- [Large Scale GAN Training for High Fidelity Natural Image Synthesis](https://mlsanity.com/paper/1809.11096/) (2018)
- [Informer: Beyond Efficient Transformer for Long Sequence Time-Series Forecasting](https://mlsanity.com/paper/2012.07436/) (2020)
- [Transformers are RNNs: Fast Autoregressive Transformers with Linear Attention](https://mlsanity.com/paper/2006.16236/) (2020)
- [Big Bird: Transformers for Longer Sequences](https://mlsanity.com/paper/2007.14062/) (2020)
- [Reformer: The Efficient Transformer](https://mlsanity.com/paper/2001.04451/) (2020)
- [Rethinking Attention with Performers](https://mlsanity.com/paper/2009.14794/) (2020)
- [Tokens-to-Token ViT: Training Vision Transformers from Scratch on ImageNet](https://mlsanity.com/paper/2101.11986/) (2021)
- [Efficient Transformers: A Survey](https://mlsanity.com/paper/2009.06732/) (2020)
- [Long Range Arena: A Benchmark for Efficient Transformers](https://mlsanity.com/paper/2011.04006/) (2020)
- [Efficient Content-Based Sparse Attention with Routing Transformers](https://mlsanity.com/paper/2003.05997/) (2020)
- [An Introduction to Matrix Concentration Inequalities](https://mlsanity.com/paper/1501.01571/) (2015)
- [Scatterbrain: Unifying Sparse and Low-rank Attention Approximation](https://mlsanity.com/paper/2110.15343/) (2021)
- [Pixelated Butterfly: Simple and Efficient Sparse training for Neural Network Models](https://mlsanity.com/paper/2112.00029/) (2021)
- [Skyformer: Remodel Self-Attention with Gaussian Kernel and Nystr"om Method](https://mlsanity.com/paper/2111.00035/) (2021)
- [SMYRF: Efficient Attention using Asymmetric Clustering](https://mlsanity.com/paper/2010.05315/) (2020)
- [Hashing-Based-Estimators for Kernel Density in High Dimensions](https://mlsanity.com/paper/1808.10530/) (2018)
- [Kernel Density Estimation through Density Constrained Near Neighbor Search](https://mlsanity.com/paper/2011.06997/) (2020)
- [ViTALiTy: Unifying Low-rank and Sparse Approximation for Vision Transformer Acceleration with a Linear Taylor Attention](https://mlsanity.com/paper/2211.05109/) (2022)

## Built on by (most cited first, 30 of 58)

- [H2O: Heavy-Hitter Oracle for Efficient Generative Inference of Large Language Models](https://mlsanity.com/paper/2306.14048/) (2023)
- [MagicPIG: LSH Sampling for Efficient LLM Generation](https://mlsanity.com/paper/2410.16179/) (2024)
- [Fast Attention Requires Bounded Entries](https://mlsanity.com/paper/2302.13214/) (2023)
- [HyperAttention: Long-context Attention in Near-Linear Time](https://mlsanity.com/paper/2310.05869/) (2023)
- [Attention Scheme Inspired Softmax Regression](https://mlsanity.com/paper/2304.10411/) (2023)
- [An Over-parameterized Exponential Regression](https://mlsanity.com/paper/2303.16504/) (2023)
- [Solving Regularized Exp, Cosh and Sinh Regression Problems](https://mlsanity.com/paper/2303.15725/) (2023)
- [How to Capture Higher-order Correlations? Generalizing Matrix Softmax Attention to Kronecker Computation](https://mlsanity.com/paper/2310.04064/) (2023)
- [The Closeness of In-Context Learning and Weight Shifting for Softmax Regression](https://mlsanity.com/paper/2304.13276/) (2023)
- [Randomized and Deterministic Attention Sparsification Algorithms for Over-parameterized Feature Dimension](https://mlsanity.com/paper/2304.04397/) (2023)
- [An Iterative Algorithm for Rescaled Hyperbolic Functions Regression](https://mlsanity.com/paper/2305.00660/) (2023)
- [In-Context Learning for Attention Scheme: from Single Softmax Regression to Multiple Softmax Regression via a Tensor Trick](https://mlsanity.com/paper/2307.02419/) (2023)
- [InfoPrompt: Information-Theoretic Soft Prompt Tuning for Natural Language Understanding](https://mlsanity.com/paper/2306.04933/) (2023)
- [A Fast Optimization View: Reformulating Single Layer Attention in LLM Based on Tensor and SVM Trick, and Solving It in Matrix Multiplication Time](https://mlsanity.com/paper/2309.07418/) (2023)
- [The Fine-Grained Complexity of Gradient Computation for Training Large Language Models](https://mlsanity.com/paper/2402.04497/) (2024)
- [Training Tensor Attention Efficiently: From Cubic to Almost Linear Time](https://mlsanity.com/paper/2405.16411/) (2024)
- [A Mathematical Abstraction for Balancing the Trade-off Between Creativity and Reality in Large Language Models](https://mlsanity.com/paper/2306.02295/) (2023)
- [Differentially Private Attention Computation](https://mlsanity.com/paper/2305.04701/) (2023)
- [GradientCoin: A Peer-to-Peer Decentralized Large Language Models](https://mlsanity.com/paper/2308.10502/) (2023)
- [Multi-Layer Transformers Gradient Can be Approximated in Almost Linear Time](https://mlsanity.com/paper/2408.13233/) (2024)
- [Solving Attention Kernel Regression Problem via Pre-conditioner](https://mlsanity.com/paper/2308.14304/) (2023)
- [A Tighter Complexity Analysis of SparseGPT](https://mlsanity.com/paper/2408.12151/) (2024)
- [Beyond Classical Attention: Quantum Attention for Scalable Computation](https://mlsanity.com/paper/2307.08045/) (2023)
- [Zero-th Order Algorithm for Softmax Attention Optimization](https://mlsanity.com/paper/2307.08352/) (2023)
- [Why Softmax Attention Outperforms Linear Attention](https://mlsanity.com/paper/2310.11685/) (2023)
- [What Can We Learn from State Space Models for Machine Learning on Graphs?](https://mlsanity.com/paper/2406.05815/) (2024)
- [A Unified Scheme of ResNet and Softmax](https://mlsanity.com/paper/2309.13482/) (2023)
- [Unmasking Transformers: A Theoretical Approach to Data Recovery via Attention Weights](https://mlsanity.com/paper/2310.12462/) (2023)
- [Addax: Utilizing Zeroth-Order Gradients to Improve Memory Efficiency and Performance of SGD for Fine-Tuning Language Models](https://mlsanity.com/paper/2410.06441/) (2024)
- [Video Latent Flow Matching: Optimal Polynomial Projections for Video Interpolation and Extrapolation](https://mlsanity.com/paper/2502.00500/) (2025)

## Abstract (arXiv)

Dot-product attention mechanism plays a crucial role in modern deep architectures (e.g., Transformer) for sequence modeling, however, na"ive exact computation of this model incurs quadratic time and memory complexities in sequence length, hindering the training of long-sequence models. Critical bottlenecks are due to the computation of partition functions in the denominator of softmax function as well as the multiplication of the softmax matrix with the matrix of values. Our key observation is that the former can be reduced to a variant of the kernel density estimation (KDE) problem, and an efficient KDE solver can be further utilized to accelerate the latter via subsampling-based fast matrix products. Our proposed KDEformer can approximate the attention in sub-quadratic time with provable spectral norm bounds, while all prior results merely provide entry-wise error bounds. Empirically, we verify that KDEformer outperforms other attention approximations in terms of accuracy, memory, and runtime on various pre-trained models. On BigGAN image generation, we achieve better generative scores than the exact computation with over 4× speedup. For ImageNet classification with T2T-ViT, KDEformer shows over 18× speedup while the accuracy drop is less than 0.5%.