On the Impact of Cluster Configuration on RoCE Application Design

RDMA over Converged Ethernet (RoCE) allows RDMA-enabled NICs to operate in datacenter networks. This study focuses on identifying how different aspects of datacenter cluster configuration impact the latency, and throughput, and CPU utilization of different ways of transferring data in RoCE (RDMA verbs). We look into the impact of colocated applications competing for both the CPU and access to the NIC as well as the impact of the network MTU. We find that RDMA applications do not fairly share the NIC, large frames should not be used, and that correct verb choice is dependent on many variables, including application access patterns, object size, and the load of both the local and remote CPU.