From 6168621d4259dba1f7c4e59f12880cf4ed5592a8 Mon Sep 17 00:00:00 2001 From: Jim Garlick Date: Thu, 1 Apr 2021 15:02:33 -0700 Subject: [PATCH] faqs: what versions of OpenMPI work with Flux? Problem: some versions of OpenMPI work with Flux and some do not, and it would be helpful to users to know which ones should work. Add a FAQ entry. --- faqs.rst | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/faqs.rst b/faqs.rst index 9ef06099..d989aa37 100644 --- a/faqs.rst +++ b/faqs.rst @@ -115,3 +115,19 @@ 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, `a bug `_ broke the Flux plugins in versions 3.1.0 through 4.0.1 (inclusive). The `the trivial fix `_ may be back-ported to the broken versions, if needed. + +The OpenMPI project dropped the Flux plugins--in fact, that whole abstraction layer that contains them--in the development branch that will become major version 5. 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 `_.