Cited by 149Advanced Neural Network ApplicationsParallel Computing and Optimization TechniquesLow-power high-performance VLSI design

The DOI matches its Crossref record; 22 of the 23 references it cites were found in a registry or an index.

Softermax: Hardware/Software Co-Design of an Efficient Softmax for Transformers

Open access
Stevens, Jacob R., Venkatesan, Rangharajan, Dai, Steve, Khailany, Brucek, Raghunathan, Anand·2021·2021 58th ACM/IEEE Design Automation Conference (DAC)

Abstract

Transformers have transformed the field of natural language processing. Their superior performance is largely attributed to the use of stacked “self-attention” layers, each of which consists of matrix multiplies as well as softmax operations. As a result, unlike other neural networks, the softmax operation accounts for a significant fraction of the total run-time of Transformers. To address this, we propose Softermax, a hardware-friendly softmax design. Softermax consists of base replacement, low-precision softmax computations, and an online normalization calculation. We show Softermax results in 2.35x the energy efficiency at 0.90x the size of a comparable baseline, with negligible impact on network accuracy.

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Crossref · 10.1109/dac18074.2021.9586134

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Figures

Fig. 1 Runtime breakdown for BERT-Large on a Volta GPU. Softmax contributes a larger fraction of the run time in Transformers than other DNNs, particularly at the longer sequence lengths seen in state-of-the-art networks
Fig. 1 Runtime breakdown for BERT-Large on a Volta GPU. Softmax contributes a larger fraction of the run time in Transformers than other DNNs, particularly at the longer sequence lengths seen in state-of-the-art networksCC-BY-NC-ND · From the PDF
Fig. 2 A Transformer layer consists of a multi-headed self attention block and a feedforward block. Of particular note is the use of softmax as a crucial operation in the self-attention block.
Fig. 2 A Transformer layer consists of a multi-headed self attention block and a feedforward block. Of particular note is the use of softmax as a crucial operation in the self-attention block.CC-BY-NC-ND · From the PDF
Fig. 3 The algorithmic changes proposed in Softermax consist of: (1) replacing e x with a low-precision implementation of 2 x , (2) replacing an explicit pass to calculate the max with an online version, and (3) replacing the maximum function with an integer-based version to simplify the renormalization calculations.
Fig. 3 The algorithmic changes proposed in Softermax consist of: (1) replacing e x with a low-precision implementation of 2 x , (2) replacing an explicit pass to calculate the max with an online version, and (3) replacing the maximum function with an integer-based version to simplify the renormalization calculations.CC-BY-NC-ND · From the PDF
Fig. 4 (a) The Unnormed Softmax Unit determines the local max, performs the power of 2 calculation using the current max, and accumulates the denominator. (b) The Normalization Unit performs the renormalization of the numerator, as well as the final division of the numerator by the accumulated sum. (c) In an example accelerator [17], the Unnormed Softmax can be integrated into the post-processing vector unit on a per PE basis, while the Normalization Unit can be shared across multiple PEs and integrated between the PEs and the Global Buffer
Fig. 4 (a) The Unnormed Softmax Unit determines the local max, performs the power of 2 calculation using the current max, and accumulates the denominator. (b) The Normalization Unit performs the renormalization of the numerator, as well as the final division of the numerator by the accumulated sum. (c) In an example accelerator [17], the Unnormed Softmax can be integrated into the post-processing vector unit on a per PE basis, while the Normalization Unit can be shared across multiple PEs and integrated between the PEs and the Global BufferCC-BY-NC-ND · From the PDF
Fig. 5 Energy consumption of a Softermax -based PE vs a DesignWare baseline for SELF+Softmax as the sequence length increases. We evaluate 16- and 32-wide implementations.
Fig. 5 Energy consumption of a Softermax -based PE vs a DesignWare baseline for SELF+Softmax as the sequence length increases. We evaluate 16- and 32-wide implementations.CC-BY-NC-ND · From the PDF

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Research works printed but not linked: 2

  1. 2017, Nvidia tesla v100 gpu architecture
  2. radford, 2019, Language models are unsupervised multitask learners, OpenAIRE blog, 1, 9

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Metadata

Authors
Stevens, J. R., Venkatesan, R., Dai, S., Khailany, B., & Raghunathan, A.
Affiliations
  • Purdue University West Lafayette (US)
  • Nvidia (United Kingdom) (GB)
Venue
2021 58th ACM/IEEE Design Automation Conference (DAC)
Publisher
IEEE
Published
2021-12-05
Pages
469-474
ISSN
0738-100X (ISSN-L)
OpenAlex
W3137649401
Cited by
148
References
23
Citations by year
2026: 22 · 2025: 68 · 2024: 35 · 2023: 16 · 2022: 5 · 2021: 2
FWCI
4.74
Type
conference paper
Language
en
Open access
Locations
  • ACM/IEEE Design Automation Conference (DAC) (publishedVersion)
  • arXiv (Cornell University) (submittedVersion, cc-by-nc-nd)
  • arXiv (Cornell University) (submittedVersion)
  • arXiv (Cornell University)
Topics
  • Physical Sciences › Computer Science › Computer Vision and Pattern Recognition › Advanced Neural Network Applications
  • Physical Sciences › Computer Science › Hardware and Architecture › Parallel Computing and Optimization Techniques
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Low-power high-performance VLSI design
Keywords
softmax, transformer models, hardware-software co-design, self-attention, low-precision arithmetic, energy efficiency, neural network acceleration

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