Fine-Grained Structured Sparse Computing for FPGA-Based AI Inference

With the explosive growth in the number of parameters in deep neural networks (DNNs), sparsity-centric algorithm and hardware designs have become critical for low-latency AI serving systems. However, the inherent randomness in pruning methods often leads to fragmented data access and irregular computation patterns in sparse matrices, resulting in significantly reduced hardware efficiency. Addressing the balance between the ‘randomness’ required to maintain model accuracy and the ‘regularity’ needed for efficient hardware design is crucial for realizing effective sparse computing in AI. This article proposes a fine-grained structured sparsity (FSS) paradigm. The pruned sparse matrices in this paradigm exhibit characteristics of ‘local randomness’ and ‘global regularity’. This dual-feature design allows AI accelerator hardware based on the FSS paradigm to maintain both high model accuracy and efficient hardware design. We implemented this novel accelerator on the Xilinx Alveo U280 and validated our concept across three different AI models, including CNN, RNN, and LLM, demonstrating performance that significantly outperforms prior methods.