SpikeStream: Accelerating Spiking Neural Network Inference on RISC-V Clusters with Sparse Computation Extensions

Spiking Neural Network (SNN) inference has a clear potential for high energy efficiency as computation is triggered by events. However, the inherent sparsity of events poses challenges for conventional computing systems, driving the development of specialized neuromorphic processors, which come with high silicon area costs and lack the flexibility needed for running other computational kernels, limiting widespread adoption. In this paper, we explore the low-level software design, parallelization, and acceleration of SNNs on general-purpose multicore clusters with a low-overhead RISC-V ISA extension for streaming sparse computations. We propose SpikeStream, an optimization technique that maps weights accesses to affine and indirect register-mapped memory streams to enhance performance, utilization, and efficiency. Our results on the end-to-end Spiking-VGG11 model demonstrate a significant 4.39× speedup and an increase in utilization from 9.28% to 52.3 % compared to a non-streaming parallel baseline. Additionally, we achieve an energy efficiency gain of 3.46× over LSMCore and a performance gain of 2.38× over Loihi.