This paper presents an architecture for Quality of Service (QoS) control of time- sensitive applications in multi-programmed embedded systems. In such systems, tasks must receive appropriate timeliness guarantees from the Operating System independently from one another, otherwise the QoS experienced by users may decrease. Moreover, fluctuations in time of the workloads make a static partitioning of the CPU not appropriate nor convenient, whereas an adaptive allocation based on an on-line monitoring of the application behaviour leads to an optimum design. By combining a resource reservation scheduler and a feedback based mechanism, we allow applications to meet their QoS requirements with the minimum possible impact on CPU occupation. We implemented the framework in AQuoSA [8], a software architecture that runs on top of the Linux kernel.We provide extensive experimental validation of our results and offer evaluation of the introduced overhead, which is perfectly sustainable in the class of addressed applications.