Hardware and Software Co-Design for Optimized Decoding Schemes and Application Mapping in NVM Compute-in-Memory Architectures

The computation-in nonvolatile memory (NVM-CiM) approach addresses the growing computational demands and the memory-wall problem faced by traditional processor-centric architectures. Computation-in-memory (CiM) capitalizes on the parallel nature of memory arrays enabling effective computation through multirow memristor reading and sensing. In this context, the conventional design of memory decoders needs to be accordingly modified for efficient multirow activation and parallel data processing. This article presents the design and optimization of address decoders for NVM-CiM system architectures, employing a cross-layer co-optimization approach that integrates circuit and architecture design with application requirements. Our methodology starts at the circuit level, examining various decoder designs, including cascaded, hierarchical, latched, and hybrid models. An in-depth application-level characterization follows, utilizing an extended NVM-CiM-capable gem5 simulator to assess the impact of these decoders on the mapping of CiM-friendly applications and the resulting system performance, particularly in facilitating rapid and efficient activation of multirow memory configurations. This holistic analysis allows us to identify the bottlenecks and requirements from the application side and adjust the design of the decoder accordingly. Our analysis reveals that Hybrid Decoders significantly decrease latency and power consumption compared to other decoder designs within NVM-CiM systems. This highlights the crucial role of the decoder's row selection flexibility, reducing additional system-level data movement even at the expense of its performance, can substantially improve the overall efficiency of NVM-CiM systems.