HI Craig,
Its not essential to use the pmix lib used to build the SLURM pmix plugin but
it does reduce likelihood of problems.
I don’t know how, but there is some way that the admin installing SLURM can
“name” the available pmix –mpi options.
For instance on one of our systems, the admin has built multiple variants of
the pmix plugin:
MPI plugin types are...
cray_shasta
none
pmi2
pmix
specific pmix plugin versions available:
pmix_v2,pmix_v3,pmix_v314,pmix_v4,pmix_v422
This naming convention has helped us with “decoupling” building of Open MPI
from SLURM build, but does mean some coordination with the sys admins.
We’re using SLURM 22.05.6
Hope this helps,
Howard
From: slurm-users <slurm-users-boun...@lists.schedmd.com> on behalf of Craig
<cfre...@super.org>
Reply-To: Slurm User Community List <slurm-users@lists.schedmd.com>
Date: Monday, March 27, 2023 at 2:01 PM
To: "slurm-users@lists.schedmd.com" <slurm-users@lists.schedmd.com>
Subject: Re: [slurm-users] [EXTERNAL] OpenMPI and Slurm clarification?
conf.log...
checking if user requested PMI support
result: no
checking if user requested internal PMIx support(yes)
result: no
checking for pmix.h in /usr
result: not found
checking for pmix.h in /usr/include
result: not found
WARNING: discovered external PMIx version is less than internal version 3.x
WARNING: using internal PMIx
So is looks like it used the internal version (which is what I was aiming for)
and that's ok by me since it seems to be working, but if I'm really supposed to
be using the same one that SLURM used then I'm gonna have to figure out a way
to determine what that was/is.
On 3/27/23 15:28, Pritchard Jr., Howard wrote:
HI Craig,
Your use of the –with-pmix on the open mpi configure line is important.
Without any args to this configure option open mpi configure will first check
if there’s an external pmix which is newer than the one that is included in the
openmpi release tarball. If it is not, the internal pmix is built.
You can check in the config.log whether the internal PMix or an external one
was used.
If you want to be extra careful, find the location of the PMIx v3 used to build
the SLURM PMIx plugin, and then rebuild your open mpi 4.1.5 with
./configure … --with-pmix=path_to_pmix_used_for_slurm_pmix_plugin_build ….
But you may be okay without doing this. You can check this by running your
open mpi job with
srun –mpi=pmix_v3 -N2 foo
and see if it behaves as expected.
I’m not sure what the “openmpi” result from srun –mpi=list is about.
Howard
From: slurm-users
<slurm-users-boun...@lists.schedmd.com><mailto:slurm-users-boun...@lists.schedmd.com>
on behalf of Craig <cfre...@super.org><mailto:cfre...@super.org>
Reply-To: Slurm User Community List
<slurm-users@lists.schedmd.com><mailto:slurm-users@lists.schedmd.com>
Date: Monday, March 27, 2023 at 12:54 PM
To: "slurm-users@lists.schedmd.com"<mailto:slurm-users@lists.schedmd.com>
<slurm-users@lists.schedmd.com><mailto:slurm-users@lists.schedmd.com>
Subject: Re: [slurm-users] [EXTERNAL] OpenMPI and Slurm clarification?
srun: MPI types are...
srun: none
srun: openmpi
srun: pmix_v3
srun: pmi2
srun: pmix
but I'm not sure that tells me much about how I am supposed to be building
OpenMPI?
On 3/27/23 14:41, Pritchard Jr., Howard wrote:
HI Craig,
If you run
srun –mpi=list
what does slurm report?
That will help in determining what argument you want to supply for the –mpi
srun option.
Howard
From: slurm-users
<slurm-users-boun...@lists.schedmd.com><mailto:slurm-users-boun...@lists.schedmd.com>
on behalf of Craig <cfre...@super.org><mailto:cfre...@super.org>
Reply-To: Slurm User Community List
<slurm-users@lists.schedmd.com><mailto:slurm-users@lists.schedmd.com>
Date: Monday, March 27, 2023 at 12:38 PM
To: "slurm-users@lists.schedmd.com"<mailto:slurm-users@lists.schedmd.com>
<slurm-users@lists.schedmd.com><mailto:slurm-users@lists.schedmd.com>
Subject: [EXTERNAL] [slurm-users] OpenMPI and Slurm clarification?
Can someone please clarify the "best practices" for building OpenMPI compatible
with Slurm?
https://slurm.schedmd.com/mpi_guide.html#open_mpi<https://urldefense.com/v3/__https:/slurm.schedmd.com/mpi_guide.html*open_mpi__;Iw!!Bt8fGhp8LhKGRg!Cb86a2IwxgqfT5fv1_eEByDpAyhly3ZdN6Wwl7Wod9FRPx9HBpvFVojIRgu5oSpti_3jOXhNyvJqEMGs$>
tells me what I _can_ do but I'm unclear as to what I _should_ do.
I've built OpenMPI 4.1.5 with: --with-pmix --with-libevent=internal
--with-hwloc=internal --with-slurm. If I run an MPI program on my cluster
(slurm 18.08.8) with "srun -N2 foo" it seems to work fine. (slurm.conf has
MpiDefault=pmix).
If I "srun --mpi=openmpi -N2 foo" it chokes with:
OPAL_ERROR: Unreachable in file
../../../../../opal/mca/pmix/pmix3/pmix3x_client.c at line 112
-------------------------------------------------------------------------------------------------------------------
This application appears to have been direct launched using "srun",
but OMPI was not build with SLURM's PMI support and therefore cannot
execute. There are several options for building PMI support under
SLURM, depending upon the SLURM version you are using:
version 16.05 or later: you can use SLURM's PMIx support. THis
require that you configure and uild SLURM --with-pmix.
.
.
.
So I guess the question is, what is the "right" way to build OpenMPI with
Slurm. Is the fact that my non-Slurm pmix works "correct" or am I just getting
lucky that the various software I have just happens to be compatible. If I
build OpenMPI am I supposed to use Slurm's pmix/libevent/hwloc or is that
optional. If it's optional when/why might I choose to do so. If I need
Slurm's versions is there some way to find which pmix/libevent/hwloc my current
Slurm install is using? Note: my sysadmins are not going to be helpful as they
think Slurm 18 and OpenMPI 4.0.2a is adequate for users' needs :^(.
I like the idea of _not_ tying my OpenMPI to the installed Slurm just in case
our support people ever decide to upgrade system software.
Thanks.
