We propose an algorithm for assessing probabilistic performance constraints for systems including components with uncertain delays. Wemake a case for designing systems based on a probabilistic relaxation of performance constraints, as this has the potential for resulting in lower silicon area and/or power consumption. We consider a concrete example, an MPEG decoder, for which we discuss modeling and assessment of probabilistic throughput constraints. 1 Introduction This paper discusses models and algorithms to support statistical relaxations of worst case constraints on system performance. Consider, for example, a system which is designed to meet a delay constraint d and suppose the critical path's delay D p is in fact random. A design based on a worst case analysis would ensure that P#D p #d#=0:In our view, for a number of application domains, such designs may be unnecessarily conservative. For example, suppose the design constraint d can be relaxed in the sense that it can be ..