Heterogeneous die stacking of SRAM row cache and 3-D DRAM: An empirical design evaluation

As DRAM scaling becomes more challenging and its energy efficiency receives a growing concern for data center operation, an alternative approach- stacking DRAM die with thru-silicon vias (TSV) using 3-D integration technology is being undertaken by industry to address these looming issues. Furthermore, 3-D technology also enables heterogeneous die stacking within one DRAM package. In this paper, we study how to design such a heterogeneous DRAM chip for improving both performance and energy efficiency, in particular, we propose a novel floorplan and several architectural techniques to fully exploit the benefits of 3-D die stacking technology when integrating an SRAM row cache into a DRAM chip. Our multi-core simulation results show that, by tightly integrating a small row cache with its corresponding DRAM array, we can improve performance by 30% while saving dynamic energy by 31% for memory intensive applications.