Uncertainty profiles are used to study the effects of contention within cloud and service-based environments. An uncertainty profile provides a qualitative description of an environment whose quality of service (QoS) may fluctuate unpredictably. For example, the performance of an application running on a virtual machine can be affected both by the way in which resources are allocated at run-time as well as by hardware contention issues. The aim of this paper is to model the influence that cloud (or service-based) environments can have on an application's performance. % Uncertain environments are modelled by strategic games with two agents; a daemon is used to represent overload and high resource contention; an angel is used to represent an idealised resource allocation situation with no underlying contention. %An assessment of mixed-stress situations is found by finding the Nash equilibria of games constructed from uncertainty profiles. Assessments of uncertainty profiles are useful in two ways: firstly, they provide a broad understanding of how environmental stress can effect an application's performance (and reliability); secondly, they allow the effects of introducing redundancy into a computation to be assessed.

Peer Reviewed