FlashNet: Flash/network stack co-design

During the past decade, network and storage devices have undergone rapid performance improvements, delivering ultra-low latency and several Gbps of bandwidth. Nevertheless, current network and storage stacks fail to deliver this hardware performance to the applications, often due to the loss of IO efficiency from stalled CPU performance. While many efforts attempt to address this issue solely on either the network or the storage stack, achieving highperformance for networked-storage applications requires a holistic approach that considers both. In this paper, we present FlashNet, a software IO stack that unifies high-performance network properties with ash storage access and management. FlashNet builds on RDMA principles and abstractions to provide a direct, asynchronous, end-to-end data path between a client and remote ash storage. The key insight behind FlashNet is to codesign the stack's components (an RDMA controller, a ash controller, and a file system) to enable cross-stack optimizations and maximize IO efficiency. In micro-benchmarks, FlashNet improves 4kB network IOPS by 38:6% to 1:22M, decreases access latency by 43:5% to 50.4 μsecs, and prolongs the ash lifetime by 1:6-5:9× for writes. We illustrate the capabilities of FlashNet by building a Key-Value store, and porting a distributed data store that uses RDMA on it. The use of FlashNet's RDMA API improves the performance of KV store by 2×, and requires minimum changes for the ported data store to access remote ash devices.