Re: [HTCondor-users] Parallel universe - Multi-hosts MPI UCX not working

["Beaumont, Martin" <Martin.Beaumont@xxxxxxxxxxxxxxx>]

Hello again,

 

So after several tests during the path month, Iâve finally made it work.

 

First, during the configure process of compiling Open MPI, OFI support must be added:

 

Transports

-----------------------

OpenFabrics OFI Libfabric: yes

 

For me, this meant I required to install the libfabric-devel package on my system (Rocky Linux 8.x).

This made jobs using the openib work again with Open MPI 4.1.x under condor, but still wasnât working for ucx jobs.

 

Second, and for reasons I do not know, you have to disable btl ofi when launching ucx jobs.

In other words, Open MPI must be compiled with OFI support, but also be disabled for UCX jobs to work correctly within condor.

Simply excluding OFI support during Open MPI compilation does not make UCX jobs work under condor.

 

Here are the working mca parameters for both types of transport:

 

--mca btl ^openib,ofi --mca pml ucx --mca plm rsh     # UCX

--mca btl openib,self --mca pml ^ucx --mca plm rsh    # OpenIB

 

Some quick unprofessional benchmarks using an SU2 example shows some improvements between Open MPI versions and transports selection, at least proving that it wasnât all for nothing!

 

Open MPI            Transport            Time

4.1.4                      openib                  252s

4.1.4                      ucx                         242s

4.0.7                      openib                  250s

4.0.7                      ucx                         250s

3.1.6                      openib                  292s

3.1.6                      ucx                         287s

 

 

Martin

 

From: HTCondor-users <htcondor-users-bounces@xxxxxxxxxxx> On Behalf Of Jason Patton via HTCondor-users
Sent: November 18, 2022 5:18 PM
To: HTCondor-Users Mail List <htcondor-users@xxxxxxxxxxx>
Cc: Jason Patton <jpatton@xxxxxxxxxxx>
Subject: Re: [HTCondor-users] Parallel universe - Multi-hosts MPI UCX not working

 

Hi Martin,

 

I helped develop part of the openmpiscript a few years ago, and it hasn't been tested since the days that OpenMPI 3.x was current, so I'm not too surprised that it's probably time to look at it again. I don't know what MCA parameters are available for UCX, but maybe you could try fiddling with MCA parameters to crank up the verbosity of messages (based on your email, I'm guessing one of these could be "--mca pml_ucx_verbose 100") and send along what you find.

 

Jason Patton

 

On Thu, Nov 17, 2022 at 12:07 PM Beaumont, Martin <Martin.Beaumont@xxxxxxxxxxxxxxx> wrote:

Hello all,

 

Using Open MPI 4.x does not work when a parallel universe job requests more than 1 host. Has anyone succeeded in using ucx PML with htcondorâs openmpiscript wrapper example?

 

$CondorVersion: 9.0.15 Jul 20 2022 BuildID: 597761 PackageID: 9.0.15-1 $

$CondorPlatform: x86_64_Rocky8 $

 

Using both OpenFOAM and SU2 compiled against Open MPI 4.1.4, using the following mpirun mca arguments â--mca btl ^openib --mca pml ucx --mca plm rshâ, parallel jobs running on only 1 host complete successfully. If more than one host is requested, UCX blurps out memory allocation errors and the job fails right away. This is using an InfiniBand fabric.

 

 

[1668707979.493116] [compute1:22247:0]       ib_iface.c:966  UCX  ERROR ibv_create_cq(cqe=4096) failed: Cannot allocate memory

â. X number of cores

[compute1:22247] ../../../../../ompi/mca/pml/ucx/pml_ucx.c:309  Error: Failed to create UCP worker

--------------------------------------------------------------------------

No components were able to be opened in the pml framework.

 

This typically means that either no components of this type were

installed, or none of the installed components can be loaded.

Sometimes this means that shared libraries required by these

components are unable to be found/loaded.

 

  Host:      compute1

  Framework: pml

--------------------------------------------------------------------------

[compute1:22247] PML ucx cannot be selected

[compute1:22236] ../../../../../ompi/mca/pml/ucx/pml_ucx.c:309  Error: Failed to create UCP worker

â. X number of cores

[compute2:22723] 31 more processes have sent help message help-mca-base.txt / find-available:none found

[compute2:22723] Set MCA parameter "orte_base_help_aggregate" to 0 to see all help / error messages

 

 

If I instead use Open MPI 3.1.6, with the arguments â--mca btl openib,self --mca plm rshâ, then multi-hosts jobs complete successfully.

Also, if I use the same mpirun command with â--mca btl ^openib --mca pml ucxâ without using HTCondor (no schedd, live on cluster using passwordless ssh), multi-hosts jobs also works.

 

Since openib is already deprecated with OMPI 4.x and scheduled to be removed in 5.x (https://www.open-mpi.org/faq/?category=openfabrics#openfabrics-default-stack), instead of trying to make openib work again with OMPI 4+, Iâd prefer to find a way to make UCX work within htcondor.

Using OMPI 3.1.6 is still viable for now, but Iâm guessing weâll eventually find an OS or app version that simply wonât work with old ompi versions.

 

My wild guess is that it has something to do with âorted_launcher.sh / get_orted_cmd.sh / condor_chirpâ and UCX not being able to work together properly, but this is beyond my understanding at this point.

 

Any clues would be appreciated. Thanks!

 

Martin

 

_______________________________________________
HTCondor-users mailing list
To unsubscribe, send a message to htcondor-users-request@xxxxxxxxxxx with a
subject: Unsubscribe
You can also unsubscribe by visiting
https://lists.cs.wisc.edu/mailman/listinfo/htcondor-users

The archives can be found at:
https://lists.cs.wisc.edu/archive/htcondor-users/