Cuckoo for Clients: Disaggregated Cuckoo Hashing

RCuckoo is a fully disaggregated lock-based key/value store in which clients cooperatively access a passive memory server using exclusively one-sided RDMA operations. RCuckoo employs cuckoo hashing to enable single round-trip reads of small values while updates and deletes require only two. We introduce locality-enhanced dependent hashing that allows us to adjust the expected distance between a key’s potential table locations, dramatically improving insert performance compared to prior cuckoo-hashing approaches while limiting I/O amplification and maintaining practical maximum fill factors. We show that not only does RCuckoo outperform all existing state-of-the-art RDMA-based key/value stores when reading small values, but under severe contention RCuckoo delivers up to 7×the throughput of comparison systems across the standard set of YCSB workloads. Moreover, RCuckoo’s lease-based locking mechanism enables it to gracefully recover from 100s of client failures per second.