HybridSkipList: A Case Study of Designing Distributed Data Structure with Hybrid RDMA

RDMA (Remote Direct Memory Access) delivers both high performance and OS kernel bypass thus triggers the revolutions of the modern data center. Especially, compared with traditional Ethernet, by exploiting memory semantics operations, RDMA-based data structure has shown great potential for high scalability and CPU utilization reduction. SkipList is an elegant sorted index data structure, and yet presents low throughput upon memory semantics RDMA due to the heavy remote access. By using SkipList as a case study, we revisit the current design paradigm of RDMA such as operation type, transport type, and caching. Accordingly, we propose a one-sided/two-sided hybrid paradigm to gain high scalability and at the same time achieve high throughput based on lock-based concurrent SkipList. To reduce the number of expensive network round trips, a client-sided cache is presented. With an in-depth analysis of the design choices, we implement HybridSkipList and deploy at an eight-machine RDMA cluster. The evaluations show it can outperform two baselines by 4.41 x and 3.45 x respectively.