Modeling and evaluation of highly complex computer systems architectures

Modern computer based systems are characterized by several complexity dimensions: a non-exhaustive list includes scale, architecture, distribution, variability, flexibility, dynamics, workloads, time constraints, dependability, availability, security, performances. The design, implementation, operation, maintenance and evolution of such systems require informed decisions, that must be founded onto techniques and tools enabling an anticipated knowledge about the behavior of every subsystem, including hardware, software and interactions, and the whole system, and the relationship of the system and the external world, considering workloads, communication, sensing of physical interactions. Performance prediction, and in general behavior prediction, may exploit simulation based approaches or analytical techniques to evaluate in advance the effects of design choices, or variability under different workloads, or emerging behavior, of systems, and provide a valuable support in all the phases of the lifecycle of a system by means of proper modeling approaches. In this Special Issue we present some contributions that offer a glance on modeling and evaluation of complex computer based system, and that have been chosen in order to provide a view on different domains and different approaches, mainly focusing on simulation techniques and related applications