Balancing Performance Against Cost and Sustainability in Multi-Chip-Module GPUs

MCM-GPUs scale performance by integrating multiple chiplets within the same package. How to partition the aggregate compute resources across chiplets poses a fundamental trade-off in performance versus cost and sustainability. We propose the Performance Per Wafer (PPW) metric to explore this trade-off and we find that while performance is maximized with few large chiplets, and while cost and environmental footprint is minimized with many small chiplets, the optimum balance is achieved with a moderate number of medium-sized chiplets. The optimum number of chiplets depends on the workload and increases with increased inter-chiplet bandwidth.