Task-Node Mapping in an Arbitrary Computer Network Using SMT Solver

Abstract

The problem of mapping (assigning) application tasks to processing nodes in a distributed computer system for spacecraft is investigated in this paper. The network architecture is developed in the project ‘Scalable On-Board Computing for Space Avionics’ (ScOSA) at the German Aerospace Center (DLR). In ScOSA system the processing nodes are connected to a network with an arbitrary topology. The applications are structured as directed graphs of periodic and aperiodic tasks that exchange messages. In this paper a formal definition of the mapping problem is given. We demonstrate several ways to formulate it as a satisfiability modulo theories (SMT) problem and then use Z3, a state-of-the-art SMT solver, to produce the mapping. The approach is evaluated on a mapping problem for an optical navigation application as well as on a set of randomly generated task graphs.