diff --git a/faqs.rst b/faqs.rst index 9ef06099..c62ff8af 100644 --- a/faqs.rst +++ b/faqs.rst @@ -115,3 +115,21 @@ The interesting part of the versioning comes from the multi-repo structure. Flux A 'flux' meta-package (such as in spack or distro package managers) that would pull in compatible versions of the various sub-packages/repos is also versioned independently of any of its subcomponents. It is a similar situation for the flux-docs repo and the documentation up on readthedocs. Each repo has it's own documentation and that gets tagged and released along with the code, but the high-level "meta" documentation has it's own versioning that is divorced from any particular sub-packages/repos versioning. .. TODO: we should make a table and put it in the docs too + +---------------------------------------- +What versions of OpenMPI work with Flux? +---------------------------------------- + +Flux plugins were added to OpenMPI 3.0.0. Generally, these plugins enable OpenMPI major versions 3 and 4 to work with Flux. OpenMPI must be configured with the Flux plugins enabled. Your installed version may be checked with: + +.. code-block:: console + + $ ompi_info|grep flux + MCA pmix: flux (MCA v2.1.0, API v2.0.0, Component v4.0.3) + MCA schizo: flux (MCA v2.1.0, API v1.0.0, Component v4.0.3) + +Unfortunately, `an OpenMPI bug `_ broke the Flux plugins in OpenMPI versions 3.0.0-3.0.4, 3.1.0-3.1.4, and 4.0.0-4.0.2. The `fix `_ was backported such that the 3.0.5+, 3.1.5+, and 4.0.2+ series do not experience this issue. + +A slightly different `OpenMPI bug `_ caused segfaults of MPI in ``MPI_Finalize`` when UCX PML was used. `The fix `_ was backported to 4.0.6 and 4.1.1. If you are using UCX PML in OpenMPI, we recommend using 4.0.6+ or 4.1.1+. + +For the upcoming 5.0 release, the OpenMPI project dropped the Flux plugins and abstraction layer that contains them. There are two solutions being discussed, neither of which is implemented yet: `Running PRRTE inside a Flux allocation `_ and `Implementing a PMIx job shell plugin `_. diff --git a/spell.en.pws b/spell.en.pws index 92f41e42..dc654f96 100644 --- a/spell.en.pws +++ b/spell.en.pws @@ -477,3 +477,4 @@ dmesg eventlog eventlogs nodelist +backported