The ROme OpTimistic Simulator: Core internals and programming model

In this article we overview the ROme OpTimistic Simulator (ROOT-Sim), an open source C/MPI-based simulation package targeted at POSIX systems, which implements a general-purpose parallel/distributed simulation environment relying on the optimistic (i.e., rollback based) synchronization paradigm. It offers a very simple programming model based on the classical notion of simulation-event handlers, to be implemented according to the ANSI-C standard, and transparently supports all the services required to parallelize the execution. It also offers a set of optimized protocols (e.g. CPU scheduling and state log/restore protocols) aimed at minimizing the run-time overhead of the platform, thus allowing for high performance and scalability. Here we overview the core internal mechanisms provided by ROOTSim, together with the offered APIs and the programming model that is expected to be agreed in order to produce simulation software that can be transparently run, in a concurrent fashion, on top of the ROOT-Sim layer.