Wimpy Nodes with 10GbE: Leveraging One-Sided Operations in Soft-RDMA to Boost Memcached

Recently, various key/value stores have been proposed targeting clusters built from low-power CPUs. The typical network configuration is that the nodes in those clusters are connected using 1 Gigabit Ethernet. During the last couple of years, 10 Gigabit Ethernet has become commodity and is increasingly used within the data centers providing cloud computing services. The boost in network link speed, however, poses a challenge to the cluster nodes because filling the network link can be a CPU-intensive task. In particular for CPUs running in low-power mode, it is therefore important to spend CPU cycles used for networking as efficiently as possible. In this paper, we propose a modified Memcached architecture to leverage the one-side semantics of RDMA. We show how the modified Memcached is more CPU efficient and can serve up to 20% more GET operations than the standard Memcached implementation on low-power CPUs. While RDMA is a networking technology typically associated with specialized hardware, our solution uses soft-RDMA which runs on standard Ethernet and does not require special hardware.