Temperature-Aware DRAM Cache Management-Relaxing Thermal Constraints in 3-D Systems

High bandwidth 3-D-stacked dynamic random access memory (DRAM) has been proposed to address the memory wall in modern systems, especially when it is used as a large last-level cache (LLC). However, stacking DRAM directly on top of the processor significantly impedes the efficiency of cooling, potentially causing thermal issues both in the processor and DRAM. Dynamic thermal management (DTM) based on DRAM temperature can be heavily intrusive because the normal working temperature for DRAM is lower than the processor temperature limit. This paper shows that in many cases it is better to disable hot portions of the cache rather than apply DTM and slow down the processor. Three temperature-aware cache management mechanisms are proposed to decrease the performance impact of DTM on 3-D systems. Our experiments show these techniques can improve the performance of DRAM-targeted DTM by 26.1% on average which make 3-D systems more practical for the future high-performance computing.