Guarded Sections: Structuring Air for Wait-Free Synchronisation

This paper is about a novel approach of organising non-sequential programs to the benefit of wait-free synchronisation. Other than critical sections, processes never block at entrance to a guarded section although only one process at a time is allowed to pass through. Competing processes are forced into bypass but, if necessary and by using futures, they can synchronise on concurrent state changes. In consequence, the execution model constrains the overlapping pattern of interacting (simultaneous) processes. Thereby, in the downstream transactional stage, efficient wait-free synchronisation of the "guarding operations" is gratifying by-product. First experimental results made with a 80-way multi-core system show that non-blocking wait-free synchronised guarded sections outperform MCS-locks.