Output Rate-Controlled Scheduling Policy: End-to-End Delay Bounds Calculation

Recently many packet scheduling algorithms based on generalized processor sharing (GPS) and earliest deadline first (EDF) have been proposed in order to guarantee deterministic or statistical delay bounds. GPS provides a minimum guaranteed service rate for each session and tight end-to-end delay bounds for leaky bucket constrained sessions. However, the delay bounds are unnecessarily large because each session is served according to its associated constant weight until the session buffer is empty. EDF is the optimal scheduling algorithm in terms of schedulable region in a single-node network. However, using EDF to provide end-to-end delay bounds is problematic because the traffic will be distorted after traffic aggregation in a multi-node network. In this paper, we present a scheduling policy called output rate-controlled generalized processor sharing (ORC-GPS) in order to guarantee deterministic delay bounds. ORC-GPS is a rate-based scheduling like GPS and controls the service rate to lower the delay bounds for leaky bucket constrained sessions. We compare ORC-GPS with GPS and EDF in terms of delay bounds.