论文标题

低位和硬件符合硬件的神经网络的两个量化功率量化

Power-of-Two Quantization for Low Bitwidth and Hardware Compliant Neural Networks

论文作者

Przewlocka-Rus, Dominika, Sarwar, Syed Shakib, Sumbul, H. Ekin, Li, Yuecheng, De Salvo, Barbara

论文摘要

在低功率嵌入式设备中部署深层神经网络以进行实时约束应用程序需要优化网络的内存和计算复杂性,通常是通过量化权重。大多数现有作品都采用线性量化,这会导致重量宽度低于8的准确性降解。由于权重的分布通常是不均匀的(大多数重量集中在零左右),因此其他方法(例如对数量化)更适合,因为它们能够保留重量分布的形状更精确。此外,使用base-2对数表示允许通过以位移动替换乘法来优化乘法。在本文中,我们探讨了非线性量化技术,以利用较低的位精度并确定有利的硬件实现选项。我们开发了量化意识培训(QAT)算法,该算法允许训练低宽度的两个两个(POT)网络,并与最先进的浮点模型相同,以实现精确的不同任务。我们探索了用于三种不同量化方案的MAC单元的锅重量编码技术,并研究了用于三种不同的量化方案的硬件设计 - 均匀,锅和添加剂(APOT),以显示使用建议的方法时的效率提高。最终,实验表明,对于低宽度精度,非均匀量化的性能要比均匀的,同时,POT量化大大降低了神经网络的计算复杂性。

Deploying Deep Neural Networks in low-power embedded devices for real time-constrained applications requires optimization of memory and computational complexity of the networks, usually by quantizing the weights. Most of the existing works employ linear quantization which causes considerable degradation in accuracy for weight bit widths lower than 8. Since the distribution of weights is usually non-uniform (with most weights concentrated around zero), other methods, such as logarithmic quantization, are more suitable as they are able to preserve the shape of the weight distribution more precise. Moreover, using base-2 logarithmic representation allows optimizing the multiplication by replacing it with bit shifting. In this paper, we explore non-linear quantization techniques for exploiting lower bit precision and identify favorable hardware implementation options. We developed the Quantization Aware Training (QAT) algorithm that allowed training of low bit width Power-of-Two (PoT) networks and achieved accuracies on par with state-of-the-art floating point models for different tasks. We explored PoT weight encoding techniques and investigated hardware designs of MAC units for three different quantization schemes - uniform, PoT and Additive-PoT (APoT) - to show the increased efficiency when using the proposed approach. Eventually, the experiments showed that for low bit width precision, non-uniform quantization performs better than uniform, and at the same time, PoT quantization vastly reduces the computational complexity of the neural network.

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