Techniques for Reliability and Fault Tolerance in OpenMP

Mission critical applications, like those used in flight traffic control systems or in the reactive systems, need to be reliably executed to preserve integrity of their own operating environment and to ensure correct course of operations. The design of these systems must take into account aspects of reliability but, at the same time, cannot neglect the performance aspects. Techniques for adding reliability to computation demand for redundant processors and memory banks. Target architectures of choice are in most cases based on processors with not very high computing power and use special purpose coprocessors to perform heavy load computations, because in most applications the principal task is to control an event flow incoming from the external environment. Whenever the main target is high performance along with reliability, with little reactivity demands, the host architecture for these applications can be a general purpose parallel architecture; most suited is a shared memory multiprocessor architecture. OpenMP [1] has recently emerged as an industry standard interface for high level programming of Shared Memory parallel architectures. Using OpenMP, it is possible to write applications within a shared memory programming model, portable to a wide range of parallel computers. This paper explores the possibility to automatically produce reliable OpenMP code, starting from OpenMP code augmented with suitable directives expressing need for reliability. In this work we propose a technique and a tool for adding to the parallel functionalities offered by OpenMP compilers some new capabilities that allow for automatically obtaining reliable OpenMP codes or reliable code portions within an OpenMP code. We show how such reliable capabilities can be obtained by definition of suitable translation rules; these latter can be implemented within a sourceto-source translator that automatically generates a reliable pure OpenMP compliant code from reliable-annotated OpenMP code.