Algorithm to Technology Co-Optimization for CiM-Based Hyperdimensional Computing

Hyperdimensional computing (HDC) has been recognized as an efficient machine learning algorithm in recent years. Robustness against noise and simple computational operations, while being limited by the memory bandwidth, make it a perfect fit for the concept of computation in memory (CiM) with emerging nonvolatile memory (NVM) technologies. For an HDC accelerator based on NVM-CiM, there are different parameters from the algorithm all the way down to the technology that interact with each other and affect the overall inference accuracy as well as the energy efficiency of the accelerator. Therefore, in this paper, we propose, for the first time, a full-stack co-optimization method and use it to design an HDC accelerator based on NVM-based content addressable memory (CAM). By incorporating the device manufacturing variability and co-optimizing the algorithm and hardware design, HDC inference on our proposed NVM-based CiM accelerator can reduce the energy consumption by 3.27x, while compared to the purely software-based implementation, the inference accuracy loss is merely 0.125%.