Experiences with OpenMP in tmLQCD

Understand

An overview is given of the lessons learned from the introduction of multi-threading using OpenMP in tmLQCD.

• In particular, programming style, performance measurements, cache misses, scaling, thread distribution for hybrid codes, race conditions, the overlapping of communication and computation and the measurement and reduction of certain overheads are discussed.
• Performance measurements and sampling profiles are given for different implementations of the hopping matrix computational kernel.