[Openmp-commits] [openmp] [OpenMP] Use distributed fork/join barrier for large teams by default (PR #195473)

[Terry Wilmarth via Openmp-commits]

TerryLWilmarth wrote:

The distributed barrier was designed for the sort of cases you are encountering, but particularly for Intel hardware, so it's interesting, and great that it also seems to work well on AMD.  But since this is a specific application behavior, it's best not to change the defaults of the runtime.  Rather, just use the environment variables to select the barrier you wish to use for your specific case.  KMP_FORKJOIN_BARRIER_PATTERN=dist,dist for example.  This will get you a warning to change all barrier patterns to dist, because dist doesn't mix with other barrier algorithms.  So KMP_PLAIN_BARRIER_PATTERN and KMP_REDUCTION_BARRIER_PATTERN will need to be set too.

https://github.com/llvm/llvm-project/pull/195473