Pac-PIM: A Parallel Communication Framework for Commodity Processing-in-memory Systems

Processing-in-memory (PIM) is a promising paradigm to effectively alleviate the bottleneck of memory access for memory-intensive applications. UPMEM PIM-enabled DIMMs, the first commercially available PIM platform integrating processing elements (PEs) in DIMMs, exemplifies this trend. However, the communication overhead between the host and PIM-enabled DIMMs remains significant. Although previous studies have attempted to reduce this overhead between the host and PIM-enabled DIMMs, our detailed investigation reveals that, from the software perspective, the native communication framework fails to fully leverage its parallelism for communication. We propose to combine rank-level parallelism and process-level parallelism in the layered fashion to take advantage of these and avoid their respective drawbacks. And we revamp the native communication framework by integrating this combination to introduce Pac-PIM ( Pa rallel C ommunication Framework for PIM ). Our evaluation, conducted using real UPMEM PIM-enabled DIMMs and representative PIM-enabled applications, shows that Pac-PIM significantly improves communication performance in all scenarios, with an average speedup of 1.53× compared to the native communication framework with excellent scalability. In addition, Pac-PIM can further improve communication performance along with other optimizations.