MNEMOSENE++: Scalable Multi-Tile Design with Enhanced Buffering and VGSOT-MRAM based Compute-in-Memory Crossbar Array

Carlos Escuin, Fernando García-Redondo, Mahdi Zahedi, Pablo Ibáñez, Teresa Monreal, Víctor Viñals, José María Llabería, James Myers, Julien Ryckaert, Dwaipayan Biswas, Francky Catthoor

Abstract: This paper optimizes the MNEMOSENE architecture, a compute-in-memory (CiM) tile design integrating computation and storage for increased efficiency. We identify and address bottlenecks in the Row Data (RD) buffer that cause losses in performance. Our proposed approach includes mitigating these buffering bottlenecks and extending MNEMOSENE’s single-tile design to a multi-tile configuration for improved parallel processing. The proposal is validated through comprehensive analyses exploring the mapping of diverse neural networks evaluated on CiM crossbar arrays based on NVM technologies. These proposed enhancements lead up to 55% reduction in execution time compared to the original single-tile architecture for any general matrix multiplication (GEMM) operation. Our evaluation shows that while ReRAM and PCM offer notable energy advantages, their integration with scaled CMOS is limited, which leads to VGSOT-MRAM emerging as a promising alternative due to its good balance between energy efficiency and superior integration capabilities. The VGSOT-MRAM crossbar arrays provide $12 \times, 49 \times$, and $346 \times$ more energy efficiency than PCM, ReRAM, and STT-MRAM ones, respectively. It translates, on average for the considered workload, in $1.5 \times, 3 \times$, and $14.5 \times$ better energy efficiency of the entire system.