StageWise: Accelerating Persistent Key-Value Stores by Thread Model Redesigning
zhihua Li, Youmin Chen, Qing Wang, Youyou Lu, Jiwu Shu · IEEE Transactions on Computers · 2025
With the emergence of fast NVMe SSDs, key-value stores are becoming more CPU-efficient in order to reap their bandwidth. However, current CPU-optimized key-value stores adopt suboptimal intra- and inter-thread models, hence incurring memory-level stalling and load imbalance that hinder cores from realizing their full potential.We present STAGEWISE, an CPU-efficient key-value store on fast NVMe SSDs with high throughput. To achieve this, we introduce a new thread model for StageWise to process KV requests. Specifically, STAGEWISEconverts the processing of each KV request into multiple asynchronous stages, and thus enables pipelining across all stages. STAGEWISEfurther introduces a client-driven share-index architecture to ease inter-thread load imbalance and maximize the pipelining opportunity. Guided by Little’s Law, STAGEWISEimproves concurrency, and therefore efficiently uses CPU to reach higher throughput. Extensive experimental results show that STAGEWISEoutperforms CPUoptimized key-value stores (e.g., KVell) by up to 3.5× with writeintensive workloads, and storage-optimized ones (e.g., RocksDB) by over an order of magnitude. STAGEWISEalso shows higher read performance and excellent scalability under various workloads.