GitHub - AminRezaei0x443/memory-efficient-attention: Memory Efficient Attention (O(sqrt(n)) for Jax and PyTorch (original) (raw)

arXiv PyPI version

This is unofficial implementation of Self-attention Does Not Need O(n^2) Memory for Jax and PyTorch.

Implementation is almost same as the one proposed in the paper, with additional masking and adding bias compatibility, batch dimensions support and PyTorch implementation. For computing attention, the proposed method requires only O(sqrt(n)) memory, and the provided functions can be used as a drop-in replacement for attention calculation.

Important Note: This implementation is a trade-off between memory requirements and runtime, so you should adjust key_chunk_size and query_chunk_size parameters to achieve the best configuration for your usecase. Here is a note from the paper's authors:

While a constant chunk size for the queries and a chunk size of sqrt(n) for the keys and values is optimal for memory consumption, the runtime is also affected by the choice of chunk size in practice, which is heavily affected by the choice of hardware. Ultimately, we have to leave this trade-off to the programmer, and expose the chunk sizes as arguments query_chunk_size and key_chunk_size. In Figure 1 we provide default values for the chunk sizes that lead to minimal runtime impact (on TPUv2), while still providing significant memory savings.

Quick Start

  1. Install the library

for Jax

pip install memory-efficient-attention[jax]

for PyTorch

pip install memory-efficient-attention[torch]

for Running Tests

pip install memory-efficient-attention[testing]

  1. Compute attention with the proper function

import numpy as np

for PyTorch

from memory_efficient_attention import efficient_dot_product_attention_pt

or for Jax

from memory_efficient_attention import efficient_dot_product_attention_jax

Random Data (batch dimensions are not necessary)

b = 8 query = np.random.rand(1, b, 128, 16, 8).astype("float32") key = np.random.rand(1, b, 128, 16, 8).astype("float32") value = np.random.rand(1, b, 128, 16, 8).astype("float32")

optional, for casual tasks, ...

mask = np.random.rand(1, b, 16, 128, 128) > 0.5 bias = np.random.rand(1, b, 16, 128, 128).astype("float32") / 100

Adjust chunk sizes

efficient_dot_product_attention_jax(query, key, value, mask, bias, key_chunk_size=..., query_chunk_size=...)

Citation

Please cite if this implementation helps your research. You can use the following BibTeX entry:

@misc{memory_efficient_attention, title = {Memory Efficient Attention}, author = {Rezaei, Amin}, howpublished = {\url{github.com/AminRezaei0x443/memory-efficient-attention}}, year = {2021} }

Also, for the paper:

@misc{rabe2021selfattention, title={Self-attention Does Not Need O(n2)O(n^2)O(n2) Memory}, author={Markus N. Rabe and Charles Staats}, year={2021}, eprint={2112.05682}, archivePrefix={arXiv}, primaryClass={cs.LG} }