Queues don’t matter when you can Jump them! In this talk I will be discussing our upcoming NSDI paper which describes QJump. QJump is a simple and immediately deployable approach to controlling network interference in datacenter networks. Network interference occurs when congestion from throughput-intensive applications causes queueing that delays traffic from latency-sensitive applications. To mitigate network interference, QJump applies Internet QoS-inspired techniques to datacenter applications. Each application is assigned to a latency sensitivity level (or class). Packets from higher levels are rate-limited in the end host, but once allowed into the network can “jump-the-queue” over packets from lower levels. In settings with known node counts and link speeds, QJump can support service levels ranging from strictly bounded latency (but with low rate) through to line-rate throughput (but with high latency variance). We have implemented QJump as a Linux Traffic Control module. QJump achieves bounded latency and reduces in-network interference by up to 300×, outperforming Ethernet Flow Control (802.3x), ECN (WRED) and DCTCP. We also show that QJump improves average flow completion times, performing close to or better than DCTCP and pFabric.

Matthew P. Grosvenor is a PhD student at the University of Cambridge Computer Laboratory. He holds bachelors degrees in Mechatronic Engineering and Computer Science from the University of New South Wales in Sydney Australia. His interests lie in cross-layer optimizations of networks and operating systems, with a particular focus on netowk latency. He has completed research internships at NICTA (Sydney), Microsoft Research (Silicon Valley), Microsoft Research (Cambridge). Before moving to Cambridge, Matthew worked at the high-frequency trading firm Zomojo.