DART: Aiming for Tail-Delay Control in Reconfigurable Networks

Abstract: Many systems serve different job classes by switching among configurations. Often, reconfiguration takes a stochastic amount of time that depends on direction and can differ in distribution between configurations. Reaching a target configuration may require crossing intermediate ones. Under a high-percentile delay objective, rarely served or pass-through configurations accumulate the long-waiting jobs that dominate the sojourn-time tail. Controlling that tail couples three decisions: which target to choose, which path to take, and whether and how many jobs to serve at the configurations crossed on the way. We introduce DART, an opportunistic commitment policy that commits to a target configuration to avoid myopic detours while serving a traversed configuration only when its weighted delay or backlog justifies the pause. We show how these decisions shape the weighted sojourn-time tail. Across six stress topologies, each isolating a different tail-control challenge, DART achieves the lowest P99 sojourn time in every case, up to 23% below the strongest baseline. The advantage holds under heterogeneous, heavy-tailed, and asymmetric reconfiguration times.