Accuracy Booster: Enabling 4-bit Fixed-point Arithmetic for DNN Training

Fuente: arXiv
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Autores principales: Harma, Simla Burcu, Chakraborty, Ayan, Sperry, Nicholas, Falsafi, Babak, Jaggi, Martin, Oh, Yunho
Formato: Preprint
Publicado: 2022
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author Harma, Simla Burcu
Chakraborty, Ayan
Sperry, Nicholas
Falsafi, Babak
Jaggi, Martin
Oh, Yunho
author_facet Harma, Simla Burcu
Chakraborty, Ayan
Sperry, Nicholas
Falsafi, Babak
Jaggi, Martin
Oh, Yunho
contents The unprecedented demand for computing resources to train DNN models has led to a search for minimal numerical encoding. Recent state-of-the-art (SOTA) proposals advocate for multi-level scaled narrow bitwidth numerical formats. In this paper, we show that single-level scaling is sufficient to maintain training accuracy while maximizing arithmetic density. We identify a previously proposed single-level scaled format for 8-bit training, Hybrid Block Floating Point (HBFP), as the optimal candidate to minimize. We perform a full-scale exploration of the HBFP design space using mathematical tools to study the interplay among various parameters and identify opportunities for even smaller encodings across layers and epochs. Based on our findings, we propose Accuracy Booster, a mixed-mantissa HBFP technique that uses 4-bit mantissas for over 99% of all arithmetic operations in training and 6-bit mantissas only in the last epoch and first/last layers. We show Accuracy Booster enables increasing arithmetic density over all other SOTA formats by at least 2.3x while achieving state-of-the-art accuracies in 4-bit training.
format Preprint
id arxiv_https___arxiv_org_abs_2211_10737
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Accuracy Booster: Enabling 4-bit Fixed-point Arithmetic for DNN Training
Harma, Simla Burcu
Chakraborty, Ayan
Sperry, Nicholas
Falsafi, Babak
Jaggi, Martin
Oh, Yunho
Machine Learning
The unprecedented demand for computing resources to train DNN models has led to a search for minimal numerical encoding. Recent state-of-the-art (SOTA) proposals advocate for multi-level scaled narrow bitwidth numerical formats. In this paper, we show that single-level scaling is sufficient to maintain training accuracy while maximizing arithmetic density. We identify a previously proposed single-level scaled format for 8-bit training, Hybrid Block Floating Point (HBFP), as the optimal candidate to minimize. We perform a full-scale exploration of the HBFP design space using mathematical tools to study the interplay among various parameters and identify opportunities for even smaller encodings across layers and epochs. Based on our findings, we propose Accuracy Booster, a mixed-mantissa HBFP technique that uses 4-bit mantissas for over 99% of all arithmetic operations in training and 6-bit mantissas only in the last epoch and first/last layers. We show Accuracy Booster enables increasing arithmetic density over all other SOTA formats by at least 2.3x while achieving state-of-the-art accuracies in 4-bit training.
title Accuracy Booster: Enabling 4-bit Fixed-point Arithmetic for DNN Training
topic Machine Learning
url https://arxiv.org/abs/2211.10737