QoS-aware resource management for distributed multimedia applications^{1}

The ability of operating system and network infrastructure to provide end-to-end quality of service (QoS) guarantees in multimedia is a major acceptance factor for various distributed multimedia applications due to the temporal audio-visual and sensory information in these applications. Our constraints on the end-to-end guarantees are (1) QoS should be achieved on a general-purpose platform with a real-time extension support, and (2) QoS should be application-controllable. In order to achieve the users’ acceptance requirements and to satisfy our constraints on the multimedia systems, we need a QoS-compliant resource management which supports QoS negotiation, admission and reservation mechanisms in an integrated and accessible way. In this paper we present a new resource model and a time-variant QoS management, which are the major components of the QoS-compliant resource management. The resource model incorporates, the resource scheduler, and a new component, the resource broker, which provides negotiation, admission and reservation capabilities for sharing resources such as CPU, network or memory corresponding to requested QoS. The resource brokers are intermediary resource managers; when combined with the resource schedulers, they provide a more predictable and finer granularity control of resources to the applications during the end-to-end multimedia communication than what is available in current general-purpose networked systems. Furthermore, this paper presents the QoS-aware resource management model called QualMan, as a loadable middleware, its design, implementation, results, tradeoffs, and experiences. There are trade-offs when comparing our QualMan QoS-aware resource management in middleware and other QoS-supporting resource management solutions in kernel space. The advantage of QualMan is that it is flexible and scalable on a general-purpose workstation or PC. The disadvantage is the lack of very fine QoS granularity, which is only possible if supports are built inside the kernel. Our overall experience with QualMan design and experiments show that (1) the resource model in QualMan design is very scalable to different types of shared resources and platforms, and it allows a uniform view to embed the QoS inside distributed resource management; (2) the design and implementation of QualMan is easily portable; (3) the good results for QoS guarantees such as jitter, synchronization skew, and end-to-end delay, can be achieved for various distributed multimedia applications.