Spiking Neural Networks (SNNs) are widely used in brain-inspired computing and neuroscience research. Several many-core accelerators have been built to improve the running speed and energy efficiency of SNNs. However, current accelerators generally need explicit synchronization among all cores after each timestep of SNNs, which poses a challenge to overall efficiency. This paper proposes DepAsync, an asynchronous architecture that eliminates inter-core synchronization, facilitating fast and energy-efficient SNN inference with commendable scalability. The main idea is to exploit the dependency of neuromorphic cores predetermined at compile time. We design a DepAsync scheduler for each core to trace the running state of its dependencies and control the core to safely forward to the next timestep without waiting for other cores to complete their tasks. This approach prevents the necessity for global synchronization, allowing DepAsync to minimize core waiting time facing inherent core and time imbalance in SNN workloads. The comprehensive evaluations using five SNN workloads show that DepAsync achieves 2.47x speedup and 1.55x energy efficiency compared to the state-of-the-art synchronization architectures.

Neuromorphic hardware systems—designed as 2D-mesh structures with parallel neurosynaptic cores—have proven highly efficient at executing large-scale spiking neural networks (SNNs). A critical challenge, however, lies in mapping neurons efficiently to these cores. While existing approaches work well with regular, fully functional mesh structures, they falter in real-world scenarios where hardware has irregular shapes or non-functional cores caused by defects or resource fragmentation. To address these limitations, we propose a novel mapping method based on an innovative space-filling curve: the Adaptive Locality-Preserving (ALP) curve. Using a unique divide-and-conquer construction algorithm, the ALP curve ensures adaptability to meshes of any shape while maintaining crucial locality properties—essential for efficient mapping. Our method demonstrates exceptional computational efficiency, making it ideal for large-scale deployments. These distinctive characteristics enable our approach to handle complex scenarios that challenge conventional methods. Experimental results show that our method matches state-of-the-art solutions in regular-shape mapping while achieving significant improvements in irregular scenarios, reducing communication overhead by up to 57.1%.

Neuromorphic hardware is a multi-core computer system specifically designed to run Spiking Neuron Network (SNN) applications. As the scale of neuromorphic hardware increases, it becomes very challenging to efficiently map a large SNN to hardware. In this paper, we proposed an efficient approach to map very large scale SNN applications to neuromorphic hardware, aiming to reduce energy consumption, spike latency, and on-chip network communication congestion. The approach consists of two steps. Firstly, it solves the initial placement using the Hilbert curve, a space-filling curve with unique properties that are particularly suitable for mapping SNNs. Secondly, the Force Directed (FD) algorithm is developed to optimize the initial placement. The FD algorithm formulates the connections of clusters as tension forces, thus converts the local optimization of placement as a force analysis problem. The proposed approach is evaluated with the scale of 4 billion neurons, which is more than 200 times larger than previous research. The results show that our approach achieves state-of-the-art performance, significantly exceeding existing approaches.