The 39th IEEE International Parallel & Distributed Processing Symposium (IPDPS) 2025 

Paper Accepted at an Outstanding International Conference

(First authors: Kim Ki-hwan, Jung Hyun-seon, Ahn Seong-hoon; corresponding author: Professor Kim Young-jae)

▶ (From left) Kim Ki-hwan, master's student; Jung Hyun-seon, master's student; Ahn Seong-hoon, master's student

The paper 'KVAccel: A Novel Write Accelerator for LSM-Tree-Based KV Stores with Host-SSD Collaboration', written by Kim Ki-hwan (first author), Jung Hyun-seon (joint first author) and Ahn Seong-hoon (joint first author) of the Data-Centric Computing and Systems Laboratory (DISCOS) with Park Jun-hyuk (master's), Safdar Jamil (post-doctoral researcher), Byun Hong-su (doctoral) and Professor Kim Young-jae (corresponding author), has been accepted for publication at The 39th International Parallel & Distributed Processing Symposium (IPDPS '25).

Log-structured merge (LSM) tree based key-value stores (KVS) are widely used because they deliver high performance in write-intensive environments, but write stalls arising during compaction can degrade performance. Existing solutions throttle I/O traffic or use multiple threads to shorten compaction time, but these have the drawbacks of causing unexpected drops in throughput or increasing host CPU usage. Hardware-based approaches using FPGAs, GPUs or DPUs are effective at reducing compaction time but incur additional hardware costs. This research proposes KVACCEL, a hardware–software co-design framework that uses a dual-interface SSD to bypass write stalls. KVACCEL allocates logical NAND flash space so that it can be used through both a block interface and a key-value interface, and uses the key-value interface as a temporary write buffer during write stalls. This strategy effectively reduces write stalls and optimizes resource utilization, while consistency between host and device is maintained through a rollback process based on an in-device LSM-based write buffer and an iterator-based range scan mechanism.

On write-intensive workloads KVACCEL raised throughput by 37% over RocksDB, widely used as an industry standard, and achieved 17% higher throughput than the state-of-the-art ADOC. KVACCEL also reduced P99 latency, a quality-of-service (QoS) metric, by 30% and 20% compared with RocksDB and ADOC respectively. Kim Ki-hwan, the paper's first author, said: "I am delighted to have brought this research, which I began as an undergraduate researcher, to a good conclusion in my first semester after enrolling. It was demanding research requiring an understanding of the system as a whole, both software and hardware, but the passionate guidance and advice of Professor Kim Young-jae and collaboration with outstanding laboratory colleagues made a good result possible. This research has become the foundation of my life as a researcher, and I would like to express my deep thanks to Professor Kim Young-jae for giving me the opportunity and guiding me, and to my seniors Park Jun-hyuk (master's), Safdar Jamil (post-doctoral researcher) and Byun Hong-su (doctoral) for their help in writing the paper."

▲ KVACCEL's hybrid interface architecture within a single device

▲ The I/O redirection technique used during write stalls, KVACCEL's core technique

▲ Performance comparison of KVACCEL with RocksDB and ADOC: (a) throughput, (b) P99 latency, (c) efficiency

The 39th IEEE International Parallel & Distributed Processing Symposium (IPDPS '25) will be held at the Politecnico di Milano in Milan, Italy, from 3 to 7 June 2025. IPDPS is an international forum for presenting and discussing the latest research results in parallel and distributed computing, attended by engineers and scientists from around the world. It covers a wide range of topics including algorithms, applications, architecture, machine learning and artificial intelligence, programming models, compilers and system software. IPDPS is also listed among the outstanding conferences in the software field of the Korean Institute of Information Scientists and Engineers and among the outstanding international conferences in computer science under the BK21 Plus programme (BK IF=2).

 

References:

Conference: https://www.ipdps.org/

Paper: https://discos.sogang.ac.kr/file/2025/intl_conf/IPDPS_2025_K_Kim.pdf