CIDER: Boosting Memory-Disaggregated Key-Value Stores with Pessimistic Synchronization

Abstract

Memory-disaggregated key-value (KV) stores suffer from a severe performance bottleneck due to their I/O redundancy issues. A huge amount of redundant I/Os are generated when synchronizing concurrent data accesses, making the limited network between the compute and memory pools of DM a performance bottleneck. We identify the root cause for the redundant I/O lies in the mismatch between the optimistic synchronization of existing memory-disaggregated KV stores and the highly concurrent workloads on DM. In this paper, we propose to boost memory-disaggregated KV stores with pessimistic synchronization. We propose CIDER, a compute-side I/O optimization framework, to verify our idea. CIDER adopts a global write-combining technique to further reduce cross-node redundant I/Os. A contention-aware synchronization scheme is designed to improve the performance of pessimistic synchronization under low contention scenarios. Experimental results show that CIDER effectively improves the throughput of state-of-the-art memory-disaggregated KV stores by up to $6.6\times$ under the YCSB benchmark.

Figures (24)

• Figure 1: The throughput and retry count of the pointer array with optimistic synchronization under a highly-contented write-intensive workload.
• Figure 2: The throughput of the pointer array with optimistic and pessimistic synchronizations as a function of the number of clients.
• Figure 3: The throughput of RACE with optimistic and pessimistic synchronizations as a function of the number of clients.
• Figure 4: The actual WC rate of local WC and the theoretical upper bound as a function of the number of CNs.
• Figure 5: The throughput of optimistic and pessimistic synchronizations as a function of the skew factor (larger values mean more skew).