I doubled checked and yes, you definitely want the pmix headers and libpmix
library installed before you configure slurm.No need to use --with-pmix if pmix
is installed in standard system locations. Configure slurm and it will see the
pmix installation. After configuring slurm, but before installing it, manually
remove the pmix versions of libpmi.so* and libpmi2.so*. Install slurm and use
its versions of those libs. Test every mpi variant seen when you run `srun
--mpi=list hostname`. You should see pmi2 and pmix in that list and several
others. The pmix option will invoke a slurm plugin that is linked directly to
the libpmix.so library. If you favor using the pmix versions of pmi/pmi2,
sounds like you'll get better performancewhen using pmi/pmi2, but as mentioned,
you would want to test every mpi variant listed to make sure everything works.
On Tuesday, November 28, 2017 9:57 PM, "r...@open-mpi.org"
<r...@open-mpi.org> wrote:
My apologies - I guess we hadn’t been tracking it that way. I’ll try to add
some clarification. We presented a nice table at the BoF and I just need to
find a few minutes to post it.
I believe you do have to build slurm against PMIx so that the pmix plugin is
compiled. You then also have to specify --mpi=pmix so slurm knows to use that
plugin for this specific job.
You actually might be able to use the PMIx backward compatibility, and you
might want to do so with slurm 17.11 and above as Mellanox did a nice job of
further optimizing launch performance on IB platforms by adding fabric-based
collective implementations to the pmix plugin. If you replace the slurm libpmi
and libpmi2 with the ones from PMIx, what will happen is that PMI and PMI2
calls will be converted to their PMIx equivalent and passed to the pmix plugin.
This lets you take advantage of what Mellanox did.
The caveat is that your MPI might ask for some PMI/PMI2 feature that we didn’t
implement. We have tested with MPICH as well as OMPI and it was fine - but we
cannot give you a blanket guarantee (e.g., I’m pretty sure MVAPICH won’t work).
Probably safer to stick with the slurm libs for that reason unless you test to
ensure it all works.
On Nov 28, 2017, at 6:42 PM, Paul Edmon <ped...@cfa.harvard.edu> wrote:
Okay, I didn't see any note on the PMIx 2.1 page about versions of slurm it was
combatible with so I assumed all of them. My bad. Thanks for the correction
and the help. I just naively used the rpm spec that was packaged with PMIx
which does enable the legacy support. It seems best then to let PMIx handle
pmix solely and let slurm handle the rest. Thanks!Am I right in reading that
you don't have to build slurm against PMIx? So it just interoperates with it
fine if you just have it installed and specify pmix as the launch option?
That's neat.
-Paul Edmon-
On 11/28/2017 6:11 PM, Philip Kovacs wrote:
Actually if you're set on installing pmix/pmix-devel from the rpms and then
configuring slurm manually, you could just move the pmix-installed versions of
libpmi.so* and libpmi2.so* to a safe place, configure and install slurm which
will drop in its versions pf those libs and then either use the slurm versions
or move the the pmix versions of libpmi and libpmi2 back into place in
/usr/lib64.
On Tuesday, November 28, 2017 5:32 PM, Philip Kovacs <pkde...@yahoo.com>
wrote:
This issue is that pmi 2.0+ provides a "backward compatibility"
feature, enabled by default, which installs both libpmi.so and libpmi2.so in
addition to libpmix.so. The route with the least friction for you would
probably be to uninstall pmix, then install slurm normally, letting it install
its libpmi and libpmi2. Next configure and compile a custom pmix with that
backward feature _disabled_, so it only installs libpmix.so. Slurm will "see"
the pmix library after you install it and load it via its plugin when you use
--mpi=pmix. Again, just use the Slurm pmi and pmi2 and install pmix
separately with the backward compatible option disabled.
There is a packaging issue there in which two packages are trying to install
their own versions of the same files. That should be brought to attention of
the packages. Meantime you can work around it.
For PMIX:
./configure --disable-pmi-backward-compatibility // ... etc ...
On Tuesday, November 28, 2017 4:44 PM, Artem Polyakov <artpo...@gmail.com>
wrote:
Hello, Paul
Please see below.
2017-11-28 13:13 GMT-08:00 Paul Edmon <ped...@cfa.harvard.edu>:
So in an effort to future proof ourselves we are trying to build Slurm against
PMIx, but when I tried to do so I got the following:
Transaction check error:
file /usr/lib64/libpmi.so from install of slurm-17.02.9-1fasrc02.el7.cen
tos.x86_64 conflicts with file from package pmix-2.0.2-1.el7.centos.x86_64
file /usr/lib64/libpmi2.so from install of slurm-17.02.9-1fasrc02.el7.cen
tos.x86_64 conflicts with file from package pmix-2.0.2-1.el7.centos.x86_64
This is with compiling Slurm with the --with-pmix=/usr option. A few things:
1. I'm surprised when I tell it to use PMIx it still builds its own versions
of libpmi and pmi2 given that PMIx handles that now.
PMIx is a plugin and from multiple perspectives it makes sense to keep the
other versions available (i.e. backward compat or perf comparison)
2. Does this mean I have to install PMIx in a nondefault location? If so how
does that work with user build codes? I'd rather not have multiple versions of
PMI around for people to build against.
When we introduced PMIx it was in the beta stage and we didn't want to build
against it by default. Now it probably makes sense to assume --with-pmix by
default. I'm also thinking that we might need to solve it at the packagers
level by distributing "slurm-pmix" package that is builded and depends on the
pmix package that is currently shipped with particular Linux distro.
3. What is the right way of building PMIx and Slurm such that they
interoperate properly?
As for now it is better to have a PMIx installed in the well-known location.
And then build your MPIs or other apps against this PMIx installation. Starting
(I think) from PMIx v2.1 we will have a cross-version support that will give
some flexibility about what installation to use with application,
Suffice it to say little to no documentation exists on how to properly this,
so any guidance would be much appreciated.
Indeed we have some problems with the documentation as PMIx technology is
relatively new. Hopefully we can fix this in near future. Being the original
developer of the PMIx plugin I'll be happy to answer any questions and help to
resolve the issues.
-Paul Edmon-
--
С Уважением, Поляков Артем Юрьевич
Best regards, Artem Y. Polyakov
