[Openmp-commits] [PATCH] D107121: [OpenMP] Fix performance regression reported in bug #51235

Shilei Tian via Phabricator via Openmp-commits openmp-commits at lists.llvm.org
Wed Aug 4 09:52:13 PDT 2021

tianshilei1992 added a comment.

In D107121#2924543 <https://reviews.llvm.org/D107121#2924543>, @protze.joachim wrote:

> I think, I found the issue with the two tests:
> On our system, the default env sets `OMP_NUM_THREADS=1`. When I set `OMP_NUM_THREADS=5` before running the tests, the tests succeed. I guess you should be able to reproduce the assertion by exporting `OMP_NUM_THREADS=1` before running the tests.
> Since the tests do not specify explicit number of threads (using the `num_threads` clause or setting the env var), the team will run serially.
> The taskwait synchronization fails in that case, because the last task has td_flags.team_serial set. I think, `td_incomplete_child_tasks` needs to be maintained for serialized teams, as soon as a hidden/detached task is created in a task. @AndreyChurbanov how should we handle the synchronization for such tasks?
> For better test coverage, we should add two run lines to the tests, one setting `OMP_NUM_THREADS=1`, one setting `OMP_NUM_THREADS=5`.

Yeah, I also found the issue and reported in https://bugs.llvm.org/show_bug.cgi?id=51258.

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