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arXiv 2109.01262cs.ARcs.LG
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模拟神经网络推理加速器的精度研究

On the Accuracy of Analog Neural Network Inference Accelerators

Sandia National Laboratories(桑迪亚国家实验室);Infineon Technologies(英飞凌科技);Arizona State University(亚利桑那州立大学)

T. Patrick Xiao, Ben Feinberg, Christopher H. Bennett, Venkatraman Prabhakar, Prashant Saxena, Vineet Agrawal, Sapan Agarwal, Matthew J. Marinella

摘要:

专门的加速器最近作为降低神经网络推理的功耗的方法而受到关注。一类有前途的加速器利用非易失性存储器阵列来存储权重并在阵列内执行$\textit{in situ}$模拟计算。虽然以前的工作已经探索了模拟加速器的设计空间,以优化性能和能源效率,很少有这些加速器的准确性进行严格的评估。这项工作显示了架构设计决策,特别是在映射神经网络参数到模拟存储单元,影响推理精度。当在ImageNet上使用ResNet50进行评估时,当硬件中的模拟量与网络中的权重成比例时,系统对模拟非理想性(单元编程错误,模数转换器分辨率和阵列寄生电阻)的弹性都有所改善。此外,与先前工作的假设相反,可以通过将权重完全存储为模拟量来实现对单元不精确性的几乎等效的恢复,而不是将权重位分散在多个设备上,通常称为位切片。通过利用比例性,模拟系统设计人员可以自由地将硬件的精度与算法的需求相匹配,而不是试图保证中间结果的精度与等效数字加速器相同。这最终导致模拟加速器更准确,对模拟误差更鲁棒,并且更节能。

英文摘要:

Specialized accelerators have recently garnered attention as a method to reduce the power consumption of neural network inference. A promising category of accelerators utilizes nonvolatile memory arrays to both store weights and perform $\textit{in situ}$ analog computation inside the array. While prior work has explored the design space of analog accelerators to optimize performance and energy efficiency, there is seldom a rigorous evaluation of the accuracy of these accelerators. This work shows how architectural design decisions, particularly in mapping neural network parameters to analog memory cells, influence inference accuracy. When evaluated using ResNet50 on ImageNet, the resilience of the system to analog non-idealities - cell programming errors, analog-to-digital converter resolution, and array parasitic resistances - all improve when analog quantities in the hardware are made proportional to the weights in the network. Moreover, contrary to the assumptions of prior work, nearly equivalent resilience to cell imprecision can be achieved by fully storing weights as analog quantities, rather than spreading weight bits across multiple devices, often referred to as bit slicing. By exploiting proportionality, analog system designers have the freedom to match the precision of the hardware to the needs of the algorithm, rather than attempting to guarantee the same level of precision in the intermediate results as an equivalent digital accelerator. This ultimately results in an analog accelerator that is more accurate, more robust to analog errors, and more energy-efficient.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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