zFabric: How to virtualize lossless ethernet?

Abstract

Converged Enhanced Ethernet (CEE) is a crucial step in embracing storage, cluster, and high-performance computing fabrics under a common network. However, the adoption of lossless CEE in virtualized clusters is hindered by the lack of network hypervisor software that addresses the major issues of losslessness, i.e., head-of-line blocking and saturation trees. Our objective is to design a hypervisor that prevents miscon-figured or malicious virtual machines from filling the lossless network with stalled packets, thus compromising tenant isolation. Furthermore, we observe that current hypervisors perform compulsory isolation, management, and mobility functions, but introduce new bottlenecks on the data-path. By taking advantage of the lossless fabric, we deconstruct the existing virtualized networking stack into its core functions and consolidate them into zFabric, an efficient hypervisor that meets our aforementioned goals. To demonstrate zFabric's benefits, we evaluate a prototype implementation on a datacenter testbed. Besides resolving head-of-line blocking, zFabric improves throughputs for long flows by up to 56%, lowers CPU utilization by up to 63%, and shortens completion times by up to 7x for partition-aggregate queries when compared with current virtualized TCP stacks.