GDH+: A GPGPU-Empowered Gradient Data Hierarchy and Key-Value Separation for Optimizing LSM-Tree-Based KV Stores

The rapid growth of unstructured data has driven the widespread adoption of LSM-tree-based key-value stores (KV stores). The write amplification resulting from compaction in LSM-trees causes a performance bottleneck. Existing solutions attempt to address this issue through key-value separation strategies. However, these studies fail to optimize the memory components of LSM-trees or provide efficient garbage collection (GC) strategies that achieve high performance while minimizing CPU overhead. These limitations motivate us to propose a GPGPU-empowered gradient data hierarchy and key-value separation for optimizing KV stores, named GDH+ . We utilize GPGPU acceleration for sorting and flushing operations, optimizing the memory components of the LSM-tree. Additionally, we enhance read performance with an LRU-based memory component that distinguishes between hot and cold data, in combination with an adaptive migration strategy. Furthermore, we propose an in-place GC strategy to reduce CPU overhead while maintaining high performance. GDH+ achieves a 2 ×, 1.5 ×, and 40% improvement in write performance, read performance, and CPU utilization, respectively, compared to state-of-the-art KV stores.