Analysis of a Window-Constrained Scheduler for Real-Time and Best-Effort Packet Streams
Abstract
This paper describes how Dynamic Window-Constrained Scheduling (DWCS) can
guarantee real-time service to packets from multiple streams with
different performance objectives. We show that: (1) DWCS can guarantee that
no more than x packets miss their deadlines for every y consecutive packets
requiring service, (2) using DWCS, the delay of service to real-time packet
streams is bounded even when the scheduler is overloaded, (3) DWCS can
ensure the delay bound of any given stream is independent of other streams,
and (4) a fast response time for best-effort packet streams, in the presence
of real-time packet streams, is possible. As long as the minimum aggregate
bandwidth requirement of all real-time packet streams does not exceed the
available bandwidth, DWCS can
guarantee that each such stream does not miss more than x deadlines for
every y requests. Furthermore, if a feasible schedule exists, each stream is
guaranteed a minimum fraction of available bandwidth over a finite window of
time. Consequently, DWCS can provide bounded delay of service to each
real-time stream in a manner which is independent of other streams, while
also meeting per-stream, explicit delay and loss constraints.