On network CoProcessors for scalable, predictable media services

Abstract

This paper presents the embedded realization and experimental evaluation of a media stream scheduler on Network Interface (NI) CoProcessor boards. When using media frames as scheduling units, the scheduler is able to operate in real-time on streams traversing the Coprocessor, resulting in its ability to stream video to remote clients at real-time rates. The contributions of this paper are its detailed evaluation of the effects of placing application or kernel-level functionality, like packet scheduling on NIs, rather than the host machines to which they are attached. The main benefits of such placement are 1) that traffic is eliminated from the host bus and memory subsystem, thereby allowing increased host CPU utilization for other tasks, and 2) that NI-based scheduling is immune to host-CPU loading, unlike host-based media schedulers that are easily affected even by transient load conditions. An outcome of this work is a proposed cluster architecture for building scalable media servers by distributing schedulers and media stream producers across the multiple NIs used by a single server and by clustering a number of such servers using commodity network hardware and software.