Enhancements to 4.4 BSD UNIX for Efficient Networked Multimedia in Project MARS

Abstract

Cluster based architectures that employ inexpensive Personal Computers (PCs) interconnected by high speed commodity interconnect have been recognized as a cost-effective way of building high performance scalable Multimedia-OnDemand (MOD) storage servers [3, 4, 6, 8]. Typically, the PCs in these architectures run operating systems such as UNIX that have traditionally been optimized for interactive computing and lack fast disk-to-network data paths and support for guaranteed CPU and storage access. In this paper we report design, implementation and performance measurements of innovative enhancements to 4.4 BSD UNIX carried out to rectify these limitations in the context of our Massively-parallel And Real-time Storage (MARS) project [6]. We have proposed and implemented the following enhancements to a 4.4 BSD compliant public domain NetBSD UNIX operating system: (1) A new kernel buffer management system called Multimedia M-buf (mmbuf) which shortens the data path from a storage devic..