Abstract
We present a new distributed performance analysis service of the ASKALON integrated Grid environment for computing runtime overheads of dynamic workflows in realtime based on event correlation techniques. We illustrate a formal method to express precise overhead correlation rules, including several performance contracts as quality of service parameters based on fuzzy logic to be enforced in dynamic environments though rescheduling, various runtime optimisations, and steering techniques. We demonstrate experimental results for two real applications from material chemistry and graphics rendering domains.