Transformers are Multi-State RNNs

Fuente: arXiv
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Autori principali: Oren, Matanel, Hassid, Michael, Yarden, Nir, Adi, Yossi, Schwartz, Roy
Natura: Preprint
Pubblicazione: 2024
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author Oren, Matanel
Hassid, Michael
Yarden, Nir
Adi, Yossi
Schwartz, Roy
author_facet Oren, Matanel
Hassid, Michael
Yarden, Nir
Adi, Yossi
Schwartz, Roy
contents Transformers are considered conceptually different from the previous generation of state-of-the-art NLP models - recurrent neural networks (RNNs). In this work, we demonstrate that decoder-only transformers can in fact be conceptualized as unbounded multi-state RNNs - an RNN variant with unlimited hidden state size. We further show that transformers can be converted into $\textit{bounded}$ multi-state RNNs by fixing the size of their hidden state, effectively compressing their key-value cache. We introduce a novel, training-free compression policy - $\textbf{T}$oken $\textbf{O}$mission $\textbf{V}$ia $\textbf{A}$ttention (TOVA). Our experiments with four long range tasks and several LLMs show that TOVA outperforms several baseline compression policies. Particularly, our results are nearly on par with the full model, using in some cases only $\frac{1}{8}$ of the original cache size, which translates to 4.8X higher throughput. Our results shed light on the connection between transformers and RNNs, and help mitigate one of LLMs' most painful computational bottlenecks - the size of their key-value cache. We publicly release our code at https://github.com/schwartz-lab-NLP/TOVA
format Preprint
id arxiv_https___arxiv_org_abs_2401_06104
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Transformers are Multi-State RNNs
Oren, Matanel
Hassid, Michael
Yarden, Nir
Adi, Yossi
Schwartz, Roy
Computation and Language
Transformers are considered conceptually different from the previous generation of state-of-the-art NLP models - recurrent neural networks (RNNs). In this work, we demonstrate that decoder-only transformers can in fact be conceptualized as unbounded multi-state RNNs - an RNN variant with unlimited hidden state size. We further show that transformers can be converted into $\textit{bounded}$ multi-state RNNs by fixing the size of their hidden state, effectively compressing their key-value cache. We introduce a novel, training-free compression policy - $\textbf{T}$oken $\textbf{O}$mission $\textbf{V}$ia $\textbf{A}$ttention (TOVA). Our experiments with four long range tasks and several LLMs show that TOVA outperforms several baseline compression policies. Particularly, our results are nearly on par with the full model, using in some cases only $\frac{1}{8}$ of the original cache size, which translates to 4.8X higher throughput. Our results shed light on the connection between transformers and RNNs, and help mitigate one of LLMs' most painful computational bottlenecks - the size of their key-value cache. We publicly release our code at https://github.com/schwartz-lab-NLP/TOVA
title Transformers are Multi-State RNNs
topic Computation and Language
url https://arxiv.org/abs/2401.06104