The Mobius execution policy

Mobius is an extensible framework and tool for performance and dependability modeling, and supports multiple modeling formalisms and solvers. As a framework, Mobius must be sufficiently general to capture the various formalism behaviors. Specifically, the Mobius execution policy must be flexible enough to accommodate the execution policies of all formalisms implemented in the framework. We know of no existing execution policy which is capable of doing this and meeting the many other goals of the framework. We present the Mobius execution policy that addresses these needs. In developing the policy, we have generalized the various preemption policies and made all aspects of the execution policy state-dependent, which has never before been considered. Because all aspects may be state-dependent, we also had to relax the assumption that work proceeds at a constant rate; this is also novel. Finally, we show that within the context of Mobius, the extra structure and overhead needed to implement a particular behavior can largely be avoided except when that behavior is present in a model.