April 2025 - slurm-users - lists.schedmd.com

slurmctld keeps segfaulting, possibly during or just after backfill
by Marcus Lauer 21 Jun '26

21 Jun '26

We are running into a problem where slurmctld is segfaulting a few times a day. We had this problem with SLURM 23.11.8 and now with 23.11.10 as well, though the problem only appears on one of the several SLURM clusters we have, and all of them use one of those versions of SLURM. I was wondering if anyone has encountered a similar issue and has any thoughts on how to prevent this. Obviously we use "SchedulerType=sched/backfill" but strangely when I switched to sched/builtin for a while there were still slurmctld segfaults. We also set "SchedulerParameters=enable_user_top,bf_max_job_test=2000". I have tried turning those off but it did not help. I have also tried tweaking several other settings to no avail. Most of the cluster runs Rocky Linux 8.10 (including the slurmctld system) though we still have some Scientific Linux 7.9 compute nodes (we compile SLURM separately for those). Here is the crash-time error from journalctl: Oct 02 06:31:20 our.host.name kernel: sched_agent[2048355]: segfault at 8 ip 00007fec755d7ea8 sp 00007fec6bffe7e8 error 4 in libslurmfull.so[7fec7555a000+1f4000] Oct 02 06:31:20 our.host.name kernel: Code: 48 39 c1 7e 19 48 c1 f8 06 ba 01 00 00 00 48 d3 e2 48 f7 da 48 0b 54 c6 10 48 21 54 c7 10 c3 b8 00 00 00 00 eb da 48 8b 4f 08 <48> 39 4e 08 48 0f 4e 4e 08 49 89 c9 48 83 f9 3f 76 4e ba 40 00 00 Oct 02 06:31:20 our.host.name systemd[1]: Started Process Core Dump (PID 2169426/UID 0). Oct 02 06:31:20 our.host.name systemd-coredump[2169427]: Process 2048344 ( slurmctld) of user 991 dumped core. This is followed by a list of each of the dozen or so related threads. The one which is dumping core is first and looks like this: Stack trace of thread 2048355: #0 0x00007fec755d7ea8 bit_and_not (libslurmfull.so) #1 0x000000000044531f _job_alloc (slurmctld) #2 0x000000000044576b _job_alloc_whole_node_internal (slurmctld) #3 0x0000000000446e6d gres_ctld_job_alloc_whole_node (slurmctld) #4 0x00007fec722e29b8 job_res_add_job (select_cons_tres.so) #5 0x00007fec722f7c32 select_p_select_nodeinfo_set (select_cons_tres.so) #6 0x00007fec756e7dc7 select_g_select_nodeinfo_set (libslurmfull.so) #7 0x0000000000496eb3 select_nodes (slurmctld) #8 0x0000000000480826 _schedule (slurmctld) #9 0x00007fec753421ca start_thread (libpthread.so.0) #10 0x00007fec745f78d3 __clone (libc.so.6) I have run slurmctld with "debug5" level logging and it appears that the error occurs right after backfill considers a large number of jobs. Slurmctld could be failing at the end of backfill or when doing something which happens just after backfill runs. Usually this is the last message before the crash: [2024-09-25T18:39:42.076] slurmscriptd: debug: _slurmscriptd_mainloop: finished If anyone has any thoughts or advice on this that would be appreciated. Thank you. -- Marcus Lauer Systems Administrator CETS Group, Research Support

4 4

Optimizing CPU allocation in Slurm with hyperthreading enabled
by Guillaume COCHARD 02 Mar '26

02 Mar '26

Hello, The Slurm documentation states that "The default allocation method within a node is cyclic allocation (allocate available CPUs in a round-robin fashion across the sockets within a node)." In our case, we are using hyperthreading, which means that if two jobs requesting one CPU each arrive at the same time on an empty node, they will be assigned to the two threads of the same physical core. To improve performance, we would like Slurm to allocate CPUs (in our case, threads) in a way that prioritizes using one thread per physical core first, and only once all cores are occupied, assign the second thread of each core. This would be similar to the Least Loaded Node (LLN) approach, but instead of distributing jobs across nodes, it would distribute them across physical cores (Least Loaded Core). We do not want to disable hyperthreading; we simply want to optimize core usage when a machine is not fully loaded. We also want this to be a cluster-wide setting, and not a user and/or job setting. Our current slurm.conf contains: ConstrainCores = no SelectType = select/cons_tres SelectTypeParameters = CR_CPU_MEMORY And our cgroup.conf contains: ConstrainDevices=yes ConstrainCores=yes Does anyone know how to achieve this? Thanks, Guillaume

3 2

slurmctld hourly: Unexpected missing socket error
by Jason Ellul 13 Jan '26

13 Jan '26

Hi all, I am hoping someone can help with our problem. Every hour after restarting slurmctld the controller becomes unresponsive to commands for 1 sec, reporting errors such as: [2024-07-15T11:45:48.509] error: slurm_send_node_msg: [socket:[934767]] slurm_bufs_sendto(msg_type=RESPONSE_JOB_INFO) failed: Unexpected missing socket error [2024-07-15T11:45:48.509] error: slurm_send_node_msg: [socket:[934760]] slurm_bufs_sendto(msg_type=RESPONSE_SLURM_RC) failed: Unexpected missing socket error [2024-07-15T11:45:48.509] error: slurm_send_node_msg: [socket:[934875]] slurm_bufs_sendto(msg_type=RESPONSE_JOB_INFO) failed: Unexpected missing socket error [2024-07-15T11:45:48.509] error: slurm_send_node_msg: [socket:[934906]] slurm_bufs_sendto(msg_type=RESPONSE_JOB_INFO) failed: Unexpected missing socket error [2024-07-15T11:45:48.509] error: slurm_send_node_msg: [socket:[939016]] slurm_bufs_sendto(msg_type=RESPONSE_JOB_INFO) failed: Unexpected missing socket error It occurs consistently at around the hour mark, but generally not at other times, unless we run a reconfigure or restart the controller. We don’t see any issues in the slurmdbd.log and the errors are also always msg type RESPONSE. We have tried building a new server on different infrastructure, but the problem has persisted. Yesterday we even tried updating slurm to v24.05.1 in the hope that may provide a fix. During our troubleshooting we have: Set: * SchedulerParameters = max_rpc_cnt=400,sched_min_interval=50000,sched_max_job_start=300,batch_sched_delay=20,bf_resolution=600,bf_min_prio_reserve=2000,bf_min_age_reserve=600 * SlurmctldPort = 6808-6817 But although the stats in sdiag have improved we still see the errors. On our monitoring software we also see a drop in network and disk activity during this 1 second, always at approx. 1 hour after restarting the controller. Many Thanks in advance Jason Jason Ellul Head - Research Computing Facility Office of Cancer Research Peter MacCallum Cancer Centre

6 8

Assistance with Node Restrictions and Priority for Users in Floating Partition
by Manisha Yadav 28 Aug '25

28 Aug '25

Dear Team, I have a scenario where I need to provide priority access to multiple users from different projects for only 3 nodes. This means that, at any given time, only 3 nodes can be used in that partition, and if one user is utilizing all 3 nodes, no other user should be able to submit jobs to that partition, or their jobs should remain in the queue. To achieve this, I attempted to use QoS by creating a floating partition with some of the nodes and configuring a QoS with priority. I also set a limit with GrpTRES=gres/gpu=24, given that each node has 8 GPUs, and there are 3 nodes in total. I then attached the QoS to the partition and assigned it to the users who need access. I Also tried MaxTRES=gres/gpu=24 While this setup works as expected in the testing environment for CPUs, it is not functioning as intended in production, and it is not effectively restricting node usage in the partition. Could anyone provide suggestions or guidance on how to properly implement node restrictions along with priority? Thank you for your assistance. Best regards, Manisha Yadav ------------------------------------------------------------------------------------------------------------ [ C-DAC is on Social-Media too. Kindly follow us at: Facebook: https://www.facebook.com/CDACINDIA & Twitter: @cdacindia ] This e-mail is for the sole use of the intended recipient(s) and may contain confidential and privileged information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies and the original message. Any unauthorized review, use, disclosure, dissemination, forwarding, printing or copying of this email is strictly prohibited and appropriate legal action will be taken. ------------------------------------------------------------------------------------------------------------

4 8

knl_generic.conf seems to be ignored and Slurm adopts default settings which specify Intel motherboard and syscfg - need help to figure out why Slurm is not reading my Dell knl_generic.conf parameters
by Bryan Johnston 01 May '25

01 May '25

Hi folks I'm in the process of standing up some Stampede2 Dell C3620p KNL nodes and I seem to be hitting a blind spot. I previously "successfully" configured KNL's on an Intel board (S7200AP), with OpenHPC and Rocky8. I say "successfully" because it works but evidently my latest troubleshooting has revealed that I may have been lucky rather than an expert KNL integrator :-) I thought I knew what I was doing, but after repeating my Intel KNL recipe with the Dell system, I have unearthed my ignorance with this wonderful (but deprecated) technology (anecdotally, the KNLs offer excellent performance and power efficiency for our workloads, particularly when contrasted with our alternative available hardware). The first discovery was the "syscfg" for Intel boards is not the same as the "syscfg" for Dell boards. I've since sorted this out. The second discovery was made while troubleshooting an issue that I'm hitting. After realising that the slurmd client nodes don't seem to be reading the "knl_generic.conf" parameters that are specified in /etc/slurm on the smshost (OpenHPC parlance for head node ... And it's a Slurm config less set up), I think my original Intel solution was working out of luck more than ingenuity. For reference , the Slurm configuration for KNL now includes: ``` NodeFeaturesPlugins=knl_generic DebugFlags=NodeFeatures GresTypes=hbm ``` And I've created a separate "knl_generic.conf" that points to the Dell specific tools and features. For the Dell system, slurmd seems to ignore my knl_generic.conf file and is drawing defaults from somewhere else. Slurm still considers SystemType to be Intel, SyscfgPath to be the default location, and SyscfgTimeout to be 1000. For Dell systems, Slurm needs to have SystemType=Dell and Timeout to be 1000. I don't understand why the nodes are not reading the knl_generic file - any help or clues would be appreciated. Here's my theory on what is happening: The Intel KNL system was successful by luck ... It probably exhibited the same ignore-the-config-file but ran default NodeFeatures for some generic knl_generic settings which are stored somewhere as default parameters. I must have just lucked out when I was using my Intel KNL system because it was using the defaults (that are compatible with Intel). If this assumption is correct, the Dell system is not working because it isn't compatible with the Intel defaults. Any clues on how to successfully invoke the config file (or better debuggingtechniwues to figure out why it isn't) would be appreciated. I can share journalctl feedback if necessary. For now, I've tried changing ownership of the config files to root:slurm, copied knl_generic.conf to the compute nodes' /etc/slurm/ and also tried to specify the config file by running (on the compute nodes) "slurmd" with "-f" ... No joy; if slurmd runs successfully (when I don't screw up some random experimental settings) then it always seems to ignore knl_generic.conf and loads some default settings from somewhere. A few questions: 1. Are there default settings stored somewhere? I might be barking up the wrong tree, although I've looked for files that may clash with the config file I've created but can't find any. 2. Is there a better way to force the knl_generic file to be loaded? 3. Is the configless Slurm somehow not reading the knl_generic file to the clients? I understand that all configuration files are read from the host server. Many thanks for any help! Regards / Groete / Sala(ni) Kahle - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bryan Johnston Senior HPC Technologist II Lead: HPC Ecosystems Project HPCwire 2024's Outstanding Leader in HPC CHPC | www.chpc.ac.za | NICIS | nicis.ac.za Centre for High Performance Computing If you receive an email from me out of office hours for you, please do not feel obliged to respond during off-hours! Book time to meet with me<https://outlook.office.com/bookwithme/user/87af4906a703488386578f34e4473c74…>

1 1

Slurm and Kerberos/GSSAPI
by Burian, John 01 May '25

01 May '25

Does anyone have any experience with using Kerberos/GSSAPI and Slurm? I’m specifically wondering if there is a known mechanism for providing proper Kerberos credentials to Slurm batch jobs, such that those processes would be able to access a filesystem that requires Kerberos credentials. Some quick searching returned nothing useful. Interactive jobs have a similar problem, but I’m hoping that SSH credential forwarding can be leveraged there. I’m nothing like an expert in Kerberos, so forgive any apparent ignorance. Thanks, John

2 3

Can't specify multiple partitions when submitting GPU jobs
by milad＠earthspecies.org 29 Apr '25

29 Apr '25

Hi, I have defined a partition for each GPU type we have in the cluster. This was mainly because I have different Node types for each GPU type and I want to set `DefCpuPerGPU` `DefMemPerGPU` for each of them. Unfortunately one can't set them per node but can do that per partition. Now sometimes people don't care about the GPU type and would like any of the partitions to pick up the job. The `--partition` in `sbatch` does allow specifying multiple partitions and this works fine when I'm not specifying `--gpu`. However when I add do something like `sbatch -p A,B --gpus 1 script.sh` then I get "srun: job 6279 queued and waiting for resources" even though partition B does have a GPU to offer. Strangely if the first partition specified (i.e. A) had a free GPU it would allocate the GPU and run the job. Is this a bug? Perhaps related to this: https://groups.google.com/g/slurm-users/c/UOUVfkajUBQ

3 4

Re: Error "_check_core_range_matches_sock" when
by Gestió Servidors 29 Apr '25

29 Apr '25

Hello, Yes, I know system is single-socket, but in a similar computer, this configuration works fine... After some tests, I have realized that with SLURM 23.11.0 I can assign CPUs in "gres.conf" (and, then, use half CPU for one GPU and other half for other GPU), but with SLURM 24.11.4 I receive " _check_core_range_matches_sock". I have read "NEWS" file inside sources files in 24.11.4 tgz and it says: […] * Changes in Slurm 23.11.7 ========================== […] -- Fix issue that only left one thread on each core available when "CPUs=" is configured to total thread count on multi-threaded hardware and no other topology info ("Sockets=", "CoresPerSocket", etc.) is configured. […] So, I suppose, in version 23.11.7 SLURM corrected that behaviour. Could someone confirm that? Thanks.

1 0

Error "_check_core_range_matches_sock" when starting "slurmctld"
by Gestió Servidors 28 Apr '25

28 Apr '25

Hello, I have compiled SLURM-24.11.3 and I have configured two GPUs in my system (slurmctld and slurmd are running in the same computer). Computes has a old processor Intel i7 with 4 cores and 4 hyperthreading. Node is configured with "NodeName=mysystem CPUs=8 Boards=1 SocketsPerBoard=1 CoresPerSocket=4 ThreadsPerCore=2 RealMemory=7940 Gres=gpu:geforce_gtx_titan_x:1,gpu:geforce_gtx_titan_black:1". "lscpu" command returns: Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian 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 BIOS Model name: Intel(R) Core(TM) i7 CPU 950 @ 3.07GHz File gres.conf is: NodeName=mysystem Autodetect=off Name=gpu Type=geforce_gtx_titan_x File=/dev/nvidia0 CPUs=0-1 NodeName=mysystem Autodetect=off Name=gpu Type=geforce_gtx_titan_black File=/dev/nvidia1 CPUs=2-3 However, when I start daemon "slurmctld", system returns this error: [2025-04-28T09:35:41.003] error: _check_core_range_matches_sock: gres/gpu GRES core specification 0-1 for node aopcvis5 doesn't match socket boundaries. (Socket 0 is cores 0-3) [2025-04-28T09:35:41.003] error: Setting node aopcvis5 state to INVAL with reason:gres/gpu GRES core specification 0-1 for node aopcvis5 doesn't match socket boundaries. (Socket 0 is cores 0-3) Where is my configuration error? Thanks.

2 1

How can we put limits on interactive jobs?
by Ole Holm Nielsen 25 Apr '25

25 Apr '25

We would like to put limits on interactive jobs (started by salloc) so that users don't leave unused interactive jobs behind on the cluster by mistake. I can't offhand find any configurations that limit interactive jobs, such as enforcing a timelimit. Perhaps this could be done in job_submit.lua, but I couldn't find any job_desc parameters in the source code which would indicate if a job is interactive or not. Question: How do people limit interactive jobs, or identify orphaned jobs and kill them? Thanks a lot, Ole -- Ole Holm Nielsen PhD, Senior HPC Officer Department of Physics, Technical University of Denmark

4 4