An investigation of arbitration in servers for distributed multimedia applications

For many client-server based multimedia applications, server performance is a crucial factor. Such applications often require the reliable support of continuous real-time data streaming to deliver audio-visual data to end users. In conventional multimedia servers, storage and network controllers can operate independently and concurrently. Conflicting accesses to shared resources, such as the system bus and main memory are traditionally resolved by arbitration, which can hence affect a server's ability to deliver streams to the network concurrently. We use simulations to study a number of arbitration protocols and their effects on server performance in a video-on-demand scenario. Our findings suggest that these protocol yield comparable performance (parallel data streams), as long as storage controllers are not treated preferentially. Moreover, the maximum bus tenure of I/O devices should be restricted to avoid starvation of network controllers operating with small block size.