Experiences with adaptive QOS mapping scheme

In multimedia computing, guaranteeing Quality of Service(QOS) is one of the most important topics. If QOS values specified by users are not ensured, the users may not put up with the degraded quality of media streams. However, operating systems cannot understand QOS values specified by users directly, then the QOS values should be mapped to the CPU capacity that is required for guaranteeing the QOS values. There are two approaches for realizing the mapping. In the first approach called static mapping, the mapping is calculated before applications are started. In the second approach called dynamic mapping, the mapping is calculated at run-time. The system monitors the actual CPU utilization of continuous media applications, and adjusts their reserved CPU resources at run-time. The advantage of the approach is that it does not require to estimate the CPU utilization that each application requires. In this paper, we propose an adaptive QOS mapping scheme using a feedback control. Also, we show that high level QOS values can be adjusted according to the reserved CPU capacity by using our algorithm.