Ensuring the (re)usability of QoS-intensive software requires that it be adaptable and portable, i.e., it should be configurable to run efficiently, robustly, and predictably on a wide range of hardware, OS, network, and compiler platforms that provide fine-grained knobs to tune QoS behavior. It is therefore important that functional correctness be verified and QoS properties be validated for the configured operating contexts and environments. This section describes several feasibility studies that how Skoll can be used to assess and assure PSAs associated with functional correctness and run-time performance.