论文标题

关于缓解神经形态推理硬件中的读取障碍

On the Mitigation of Read Disturbances in Neuromorphic Inference Hardware

论文作者

Paul, Ankita, Song, Shihao, Titirsha, Twisha, Das, Anup

论文摘要

非挥发记忆(NVM)细胞用于神经形态硬件中,以存储模型参数,该参数被编程为电阻状态。 NVM遭受了读取干扰问题的困扰,在推理过程中,编程的电阻状态在重复访问细胞后会漂移。电阻漂移可以降低推理精度。为了解决这个问题,有必要定期重新编程模型参数(高间接费用操作)。我们研究读取NVM单元的干扰故障。我们的分析表明,既依赖于模型特征,例如突触激活和关键性,以及用于读取推断期间抗性状态的电压。我们提出了一个系统软件框架,以将这些依赖项纳入神经形态硬件NVM单元格上的编程模型参数中。我们的框架由凸优化公式组成,旨在实施具有更多激活且至关重要的突触权重,即那些对在推理过程中暴露于较低电压的NVM细胞准确性的高度影响的突触权重。这样,我们增加了模型参数的两个连续重编程之间的时间间隔。我们在神经形态硬件模拟器上使用许多新兴的推理模型评估了我们的系统软件,并显示了系统开销的显着降低。

Non-Volatile Memory (NVM) cells are used in neuromorphic hardware to store model parameters, which are programmed as resistance states. NVMs suffer from the read disturb issue, where the programmed resistance state drifts upon repeated access of a cell during inference. Resistance drifts can lower the inference accuracy. To address this, it is necessary to periodically reprogram model parameters (a high overhead operation). We study read disturb failures of an NVM cell. Our analysis show both a strong dependency on model characteristics such as synaptic activation and criticality, and on the voltage used to read resistance states during inference. We propose a system software framework to incorporate such dependencies in programming model parameters on NVM cells of a neuromorphic hardware. Our framework consists of a convex optimization formulation which aims to implement synaptic weights that have more activations and are critical, i.e., those that have high impact on accuracy on NVM cells that are exposed to lower voltages during inference. In this way, we increase the time interval between two consecutive reprogramming of model parameters. We evaluate our system software with many emerging inference models on a neuromorphic hardware simulator and show a significant reduction in the system overhead.

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