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Slurm 24.05 and OpenMPI
by Matthias Leopold 28 Mar '25

28 Mar '25

Hi, I built a small Slurm 21.08 cluster with NVIDIA GPU hardware and NVIDIA deepops framework a couple of years ago. It is based on Ubuntu 20.04 and makes use of the NVIDIA pyxis/enroot container solution. For operational validation I used the nccl-tests application in a container. nccl-tests is compiled with MPI support (OpenMPI 4.1.6 or 4.1.7) and I used it also for validation of MPI jobs. Slurm jobs use "pmix" and tasks are launched via srun (not mpirun). Some of the GPUs can talk to each other via Infiniband, but MPI is rarely used at our site and I'm fully aware that my MPI knowledge is very limited. Still it worked with Slurm 21.08. Now I built a Slurm 24.05 cluster based on Ubuntu 24.04 and started to move hardware there. When I run my nccl-tests container (also with newer software) I see error messages like this: [node1:21437] OPAL ERROR: Unreachable in file ext3x_client.c at line 111 -------------------------------------------------------------------------- The application appears to have been direct launched using "srun", but OMPI was not built 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 requires that you configure and build SLURM --with-pmix. Versions earlier than 16.05: you must use either SLURM's PMI-1 or PMI-2 support. SLURM builds PMI-1 by default, or you can manually install PMI-2. You must then build Open MPI using --with-pmi pointing to the SLURM PMI library location. Please configure as appropriate and try again. -------------------------------------------------------------------------- *** An error occurred in MPI_Init *** on a NULL communicator *** MPI_ERRORS_ARE_FATAL (processes in this communicator will now abort, *** and potentially your MPI job) [node1:21437] Local abort before MPI_INIT completed completed successfully, but am not able to aggregate error messages, and not able to guarantee that all other processes were killed! One simple question: Is this related to https://github.com/open-mpi/ompi/issues/12471? If so: is there some workaround? I'm very grateful for any comments. I know that a lot of detail information is missing, but maybe someone can still already give me a hint where to look. Thanks a lot Matthias

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Doubt with SelectTypeParameters in slurm.conf
by Gestió Servidors 28 Mar '25

28 Mar '25

Hello, I'm running some tests in a very small testing environment (before applying in the real scenario). My environment is only a computer with a old Intel i4 with this "lscpu" configuration: Architecture: x86_64 CPU(s): 8 On-line CPU(s) list: 0-7 Thread(s) per core: 2 Core(s) per socket: 4 Socket(s): 1 NUMA node(s): 1 Vendor ID: GenuineIntel BIOS Vendor ID: Intel(R) Corporation CPU family: 6 Model: 26 Model name: Intel(R) Core(TM) i7 CPU 950 @ 3.07GHz "slurmd -C" returns: "CPUs=8 Boards=1 SocketsPerBoard=1 CoresPerSocket=4 ThreadsPerCore=2". My slurm.conf is configured with: SelectType=select/cons_tres SelectTypeParameters=CR_Core AccountingStorageTRES=cpu,mem,node,billing,fs/disk,vmem,pages After running a simple "helloworld" test, I have noticed that if SelectTypeParameters=CR_Core, system always reserves me an even number of CPUs (during "pending" time, I can see the real number I have requested, but when job starts "running", that number is increased to the next even number). Howerver, if I reconfigure slurm with SelectTypeParameters=CR_CPU, system reserves me the correct number of CPUs (during "pending" time and, also, during "running" time). I suppose that my system must be configured with CR_CPU, according https://slurm.schedmd.com/cons_tres.html, but could someone confirm that? Thanks.

2 1

bit_cache_init failure on the second time backup controller tries to take control
by Safdar Iqbal 28 Mar '25

28 Mar '25

Hi, We're running into an issue where slurmctld core-dumps with the following error. This happens on the backup controller, if it needs to take over from the primary, _for a second time_. slurmctld: fatal: bit_cache_init: cannot change size once set Has anyone seen this error before? Also if there are any existing discussions and/or tickets related to this, please let me know. Our slurm version is 24.11.1. ________________ Steps to reproduce: 1. On a healthy cluster, we make the primary controller unavailable. Since we're running our cluster on cloud VMs, we cause this by stopping the primary controller VM. 2. From the logs we can see the backup controller take over, and log the message "Running as primary controller" 3. We then start the primary again, making sure the IP addresses and hostnames stay consistent. Once slurmctld on the primary has started and taken back control, we can see the log "Running as primary controller" on that VM. 4. We then stop the primary controller VM again, causing the backup to try taking the control a second time. This time however the slurmctld on the backup coredumps, with following log entries from journalctl -u slurmctld: slurmctld: fatal: bit_cache_init: cannot change size once set slurmctld.service: Main process exited, code=dumped, status=6/ABRT slurmctld.service: Failed with result 'core-dump'. Thanks! - Safdar

1 0

How limit CPUs per node in a partition
by Gestió Servidors 27 Mar '25

27 Mar '25

Hello, I have a testing partition with only a node. That server has 12 CPUs (it's a very old server) (2 sockets, 6 cores per socket, 1 thread per core). That partition, called "test.q" only has that node, so by default, partition test.q has 12 CPUs (all from testing node). However, now I would like to decrease that CPU number from 12 to 4, for example. "slurmd -C" returns "CPUs=12 Boards=1 SocketsPerBoard=2 CoresPerSocket=6 ThreadsPerCore=1" as I have said to you before and if in slurm.conf I configure partition in this way "PartitionName=test.q Nodes=test-node MaxTime=10:00 State=UP AllocNodes=clus-login MaxCPUsPerNode=4", partition continues accepting jobs with 12 CPUs. Is it any wrong in my configuration? How could I get my purpose? Thanks. -- [cid:image001.jpg@01DB9F0E.FDD9A7A0]<http://www.uab.cat/> Daniel Ruiz Molina Tècnic Mitjà Informàtic Arquitectura de Computadors i Sistemes Operatius Escola d'Enginyeria Edifici Q - Despatx QC/3052 - Carrer de les Sitges Campus de la UAB · 08193 Bellaterra (Cerdanyola del Vallès) · Barcelona · Spain +34 93 581 35 44 www.uab.cat<http://www.uab.cat/> Daniel Ruiz at UAB<https://tinyurl.com/yd95zb8j> [cid:image002.jpg@01DB9F0E.FDD9A7A0]<www.linkedin.com/in/daniel-ruiz-molina-50a83b27> Aquest missatge s'adreça exclusivament a la persona destinatària i pot contenir informació privada o confidencial. Si l'heu rebut per error, comuniqueu-nos-ho i destruïu-lo, i tingueu present que no teniu autorització per fer-ne cap ús. Abans d'imprimir aquest missatge penseu en el medi ambient.

1 0

Re: Using more cores/CPUs that requested with
by Shunran Zhang 26 Mar '25

26 Mar '25

Ugh I think I did not catch up with the docs. I started with a system that defaults to cgroup v1 but the Slurm doc for that plugin is NOT available at that time. Thus I converted everything to cgroup v2. It appears that they are both supported and that documentation issue is more on the dev side than admin side. Thanks for pointing that out. I misinterpreted the "coming soon" part of cgroup v1 plugin and the "legacy" naming for "do not use". It should be fine. 2025年3月27日(木) 0:48 Williams, Jenny Avis <jenny_williams(a)unc.edu>: > “ … As cgroup is likely not supposed to be used in newer deployments of > Slurm.” > > > > I am curious about this statement. Would someone expand on this, to either > support or counter it? > > > > Jenny Williams > > UNC Chapel Hill > > > > > > *From:* Shunran Zhang via slurm-users <slurm-users(a)lists.schedmd.com> > *Sent:* Wednesday, March 26, 2025 10:52 AM > *To:* Gestió Servidors <sysadmin.caos(a)uab.cat> > *Cc:* Slurm User Community List <slurm-users(a)lists.schedmd.com> > *Subject:* [slurm-users] Re: Using more cores/CPUs that requested with > > > > If you are letting systemd taking most things over, you got systemd-cgtop > that work better than top for your case. There is also systemd-cgls for > non-interactive listing. > > > > Also mind to check if you are using cgroup2? A mount to check your cgroup > would suffice. As cgroup is likely not supposed to be used in newer > deployments of Slurm. > > > > > > 2025年3月26日(水) 17:14 Gestió Servidors via slurm-users < > slurm-users(a)lists.schedmd.com>: > > Hello, > > > > Thanks for your answers. I will try now!! One more question: is there any > way to check if Cgroups restrictions is working fine during a “running” job > or during SLURM scheduling process? > > > > Thanks again! > > > > > -- > slurm-users mailing list -- slurm-users(a)lists.schedmd.com > To unsubscribe send an email to slurm-users-leave(a)lists.schedmd.com > >

1 0

Re: Using more cores/CPUs that requested with
by Gestió Servidors 26 Mar '25

26 Mar '25

Hello, Thanks for your answers. I will try now!! One more question: is there any way to check if Cgroups restrictions is working fine during a "running" job or during SLURM scheduling process? Thanks again!

4 3

Using more cores/CPUs that requested with sbatch
by Gestió Servidors 25 Mar '25

25 Mar '25

Hello, I would like to know if there is any mechanism to avoid a user to do "cheating" when he submits a job. For example, a user submits a OpenMP job requesting 1 node (-N 1) and 2 tasks (-n 2). However, inside his script (or compiled in his binany), user uses more than 2 ntasks, for example, all free cores. For SLURM, job is only using 2, but really, node is 100% assigned to that job. SLURM can control that "abuse" in some way? Cgroups? Thanks.

3 2

Re: Using more cores/CPUs that requested with sbatch
by Megan 25 Mar '25

25 Mar '25

Slurm can restrict jobs to their allocated resources using cgroups. To use cgroups you will have to configure the TaskPlugin cgroup option and specify how the cgroups should behave in cgroup.conf. slurm.conf TaskPlugin=task/cgroup Slurm Workload Manager - slurm.conf <https://slurm.schedmd.com/slurm.conf.html#OPT_task/cgroup> cgroup.conf ConstrainCores=yes Slurm Workload Manager - cgroup.conf <https://slurm.schedmd.com/cgroup.conf.html#OPT_ConstrainCores> Regards, --Megan

1 0

slurmrestd equivalent to "srun -n 10 echo HELLO"
by Dan Healy 24 Mar '25

24 Mar '25

Hi Slurm Community, I'm starting to experiment with slurmrestd for a new app we're writing. I'm having trouble understanding one aspect of submitting jobs. When I run something like `srun -n 10 echo HELLO', I get HELLO returned to my console/stdout 10x. When I submit this command as a script to the /jobs/submit route, I get success/200, but *I cannot determine how to get the console output of HELLO 10x in any form*. It's not in my stdout log for that job even though I can verify that the job ran successfully. Any suggestions? -- Thanks, Daniel Healy

3 2

Priority/Top seems to not be working
by Dan Healy 24 Mar '25

24 Mar '25

Hi Slurm Users, I have a newer install (23.11.3) and the priority of most all jobs is 1 and other small numbers. In previous versions, I would see numbers like 2^32. I have the multifactor plugin configured and confirmed it's in-use when I show the config. When I run `scontrol top` for a given job, the priority number doesn't change from 1. I have lots of jobs running at the moment and many queued as well. I've been using `scontrol top` for years and have seen the priority successfully change. I'm repeating this now with the newer version of Slurm and now seeing it work the same. Are you seeing this too? -- Thanks, Daniel Healy

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