Turn grouping for efficient barrier synchronization in wormhole mesh networks

Barrier is an important synchronization operation. On scalable parallel computers, it is often implemented as a collective communication with a reduction operation followed by a distribution operation. In this paper, we introduce a systematic way of generating efficient algorithms to perform barrier synchronization in mesh networks. The scheme works with any base routing algorithm derivable from the turn model. Our scheme extends the turn grouping method with two new algorithms, Tail to Central and Central to Tail, for scheduling the message transmission in the reduction and distribution phase respectively. Simulation results show that our approach can take advantage of the adaptivity of the turn-model based routing algorithms and outperform methods proposed previously.