Efficient User-Level Multi-Path Utilization in RDMA Networks

RDMA has become one of the most prominent networking technologies in DCNs by providing high bandwidth and ultra-lowlatency, especially for data-intensive applications. An important challenge with RDMA is to exploit multi-path for high throughput and reliability. Several studies have been proposed to utilize multi-path in RDMA networks, but they commonly require modification of RDMA NICs, which makes it hard to deploy them in practice. In this paper, we propose a user-level multi-path RDMA (UL-MPRDMA) scheme, in which a flow is partitioned into sub-flows, and transferred via multiple connections to make full use of multiple paths in DCNs. UL-MPRDMA quickly responds to sudden network trouble and congestion by performing dynamic sub-flow scheduling, and also effectively avoids the performance degradation problem due to the limited memory of RDMA NICs without the intervention of CPU. We implement UL-MPRDMA on a real test-bed with commercial RDMA NICs, and show that UL-MPRDMA can achieve 30% higher link utilization than an existing RDMA transport technique.