A Host-SSD Collaborative Write Accelerator for LSM-Tree-Based Key-Value Stores

TL;DR

This paper introduces KVACCEL, a hardware-software co-designed framework utilizing dual-interface SSDs to eliminate write stalls in LSM-tree-based key-value stores, improving throughput and efficiency for write-intensive workloads.

Contribution

KVACCEL is a novel co-design that uses a dual-interface SSD to prevent write stalls, combining hardware and software innovations for improved performance.

Findings

KVACCEL outperforms ADOC by up to 1.17x in throughput.

KVACCEL reduces write stalls significantly during intensive workloads.

Performance is comparable to existing solutions in mixed read-write scenarios.

Abstract

Log-Structured Merge (LSM) tree-based Key-Value Stores (KVSs) are widely adopted for their high performance in write-intensive environments, but they often face performance degradation due to write stalls during compaction. Prior solutions, such as regulating I/O traffic or using multiple compaction threads, can cause unexpected drops in throughput or increase host CPU usage, while hardware-based approaches using FPGA, GPU, and DPU aimed at reducing compaction duration introduce additional hardware costs. In this study, we propose KVACCEL, a novel hardware-software co-design framework that eliminates write stalls by leveraging a dual-interface SSD. KVACCEL allocates logical NAND flash space to support both block and key-value interfaces, using the key-value interface as a temporary write buffer during write stalls. This strategy significantly reduces write stalls, optimizes resource usage, and ensures consistency between the host and device by implementing an in-device LSM-based write buffer with an iterator-based range scan mechanism. Our extensive evaluation shows that for write-intensive workloads, KVACCEL outperforms ADOC by up to 1.17x in terms of throughput and performance-to-CPU-utilization efficiency. For mixed read-write workloads, both demonstrate comparable performance.