Monitoring the resources of distributed systems is essential to the successful deployment and execution of grid applications, particularly when such applications have welldefined QoS requirements. The dproc system-level monitoring mechanisms implemented for standard Linux kernels have several key components. First, utilizing the familiar /proc filesystem, dproc extends this interface with resource information collected from both local and remote hosts. Second, to predictably capture and distribute monitoring information, dproc uses a kernel-level group communication facility, termed KECho, which is based on events and event channels. Third and the focus of this paper is dproc?s run-time customizability for resource monitoring, which includes the generation and deployment of monitoring functionality within remote operating system kernels. Using dproc, we show that (a) data streams can be customized according to a client?s resource availabilities (dynamic stream management), (b) by dynamically varying distributed monitoring (dynamic .ltering of monitoring information), appropriate balance can be maintained between monitoring overheads and application quality, and (c) by performing monitoring at kernel-level, the information captured enables decision making that takes into account the multiple resources used by applications.