A simple, fast and scalable non-blocking concurrent FIFO queue for shared memory multiprocessor systems

A non-blocking FIFO queue algorithm for multiprocessor shared memory systems is presented in this paper. The algorithm is very simple, fast and scales very well in both symmetric and non-symmetric multiprocessor shared memory systems. Experiments on a 64-node SUN Enterprise 10000 — a symmetric multiprocessorsystem — and on a 64-node SGI Origin 2000 — a cache coherent non uniform memory access multiprocessorsystem — indicate that our algorithm considerably outperforms the best of the known alternatives in both multiprocessors in any level of multiprogramming. This work introduces two new, simple algorithmic mechanisms. The first lowers the contention to key variables used by the concurrent enqueue and/or dequeue operations which consequently results in the good performance of the algorithm, the second deals with the pointer recycling problem, an inconsistency problem that all non-blocking algorithms based on the compare-and-swap synchronisation primitive have to address. In our construction we selected to use compare-and-swap since compare-and-swap is an atomic primitive that scales well under contention and either is supported by modern multiprocessors or can be implemented efficiently on them.