Thwarting Virtual Bottlenecks in Multi-Bitrate Streaming Servers
Bin Liu, Raju Rangaswami, and Zoran Dimitrijevic
 
Current cycle-based disk IO schedulers for multi-bitrate streaming servers are unable to avoid the formation of virtual bottlenecks. We term a bottleneck as {\em virtual} when it occurs within a single resource subsystem, and it is possible to use a secondary under-utilized resource to thwart the bottleneck. We present {\em stream combination}, an IO scheduling technique that addresses this problem. Stream combination predicts the formation of virtual bottlenecks and proactively alters the IO schedule to avoid them. A simulation study suggests significant performance gains compared to the current state-of-the-art fixed time-cycle IO scheduler.