Scalability Evaluation of Barrier Algorithms for OpenMP

OpenMP relies heavily on barrier synchronization to coordinate the work of threads that are performing the computations in a parallel region. A good implementation of barriers is thus an important part of any implementation of this API. As the number of cores in shared and distributed shared memory machines continues to grow, the quality of the barrier implementation is critical for application scalability. There are a number of known algorithms for providing barriers in software. In this paper, we consider some of the most widely used approaches for implementing barriers on large-scale shared-memory multiprocessor systems: a “blocking” implementation that de-schedules a waiting thread, a “centralized” busy wait and three forms of distributed “busy” wait implementations are discussed. We have implemented the barrier algorithms in the runtime library associated with a research compiler, OpenUH. We first compare the impact of these algorithms on the overheads incurred for O...

• Type: Conference
• Year: 2009
• Where: IWOMP
• Authors: Ramachandra C. Nanjegowda, Oscar Hernandez, Barbara M. Chapman, Haoqiang Jin
• Keywords: Barrier Implementations, Barrier Synchronization, IWOMP 2009, OpenMP, Programming Languages