MNSIM 2.0: A Behavior-Level Modeling Tool for Processing-In-Memory Architectures

In the age of artificial intelligence (AI), the huge data movements between memory and computing units become the bottleneck of von Neumann architectures, i.e., the 'memory wall' problem. In order to tackle this challenge, processing-in-memory (PIM) architectures are proposed, which perform in-situ computations in memory and give alternative solutions to boost the computing energy efficiency and performance. Because of the large-scale neural network (NN) algorithm models and the huge hardware design space, various factors affect computing accuracy and performance, bringing the need for efficient PIM modeling and evaluation tools. In this work, we propose a behavior-level modeling tool, MNSIM 2.0, to model the performance of PIM architectures efficiently. At the hardware level, MNSIM 2.0 provides a hierarchical PIM modeling structure with flexible architecture configurability and components extensibility. Moreover, the first unified PIM memory array model is proposed for describing both digital and analog PIM. At the algorithm level, MNSIM 2.0 supports the PIM-based NN computing accuracy simulation considering various architecture and device parameters. A PIM-oriented NN model training and quantization flow is also integrated to improve the performance gain brought by PIM. At the scheduling level, MNSIM 2.0 adopts a universal scheduling description compatible with different scheduling strategies. Validation using fabricated PIM macros shows the relative modeling error rate of MNSIM 2.0 is 3.8%-5.5%. Case studies show that MNSIM 2.0 enables PIM design space explorations, influences analysis of device parameters, and architecture design insight discoveries.