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

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

Wrong MaxRSS Behavior with cgroup v2 in Slurm
by Guillaume COCHARD 19 Jun '25

19 Jun '25

Hello, We've noticed a recent change in how MaxRSS is reported on our cluster. Specifically, the MaxRSS value for many jobs now often matches the allocated memory, which was not the case previously. It appears this change is due to how Slurm accounts for memory when copying large files, likely as a result of moving from cgroup v1 to cgroup v2. Here’s a simple example: copy_file.sh #!/bin/bash cp /distributed/filesystem/file5G /tmp cp /tmp/file5G ~ Two jobs with different memory allocations: Job 1 sbatch -c 1 --mem=1G copy_file.sh seff <jobid> Memory Utilized: 1021.87 MB Memory Efficiency: 99.79% of 1.00 GB Job 2 sbatch -c 1 --mem=10G copy_file.sh seff <jobid> Memory Utilized: 4.02 GB Memory Efficiency: 40.21% of 10.00 GB With cgroup v1, this script typically showed minimal memory usage. Now, under cgroup v2, memory usage appears inflated and depends on the allocated memory, which seems wrong. I believe this behavior aligns with similar issues raised by the Kubernetes community [1], and is consistent with how memory.current behaves in cgroup v2 [3]. According to Slurm’s documentation about cgroup v2, "this plugin provides cgroup's memory.current value from the memory interface, which is not equal to the RSS value provided by procfs. Nevertheless it is the same value that the kernel uses in its OOM killer logic." [2] While technically correct, this seems to mark a significant change in what MaxRSS and "Memory Efficiency" actually measure and renders those metrics almost useless. Our Configuration: ProctrackType=proctrack/cgroup TaskPlugin=task/cgroup,task/affinity Question: Is there a way to restore more realistic MaxRSS values — specifically, ones that exclude file-backed page cache — while still using cgroup v2? Thanks, Guillaume References: [1] https://github.com/kubernetes/kubernetes/issues/118916 [2] https://slurm.schedmd.com/cgroup_v2.html#limitations [3] https://facebookmicrosites.github.io/cgroup2/docs/memory-controller.html

3 4

Restrict and prioritize usage of certain nodes according to accounts
by thomas.hartmann＠th-ht.de 09 Jun '25

09 Jun '25

Hi, I'm going to have the following situation on my hands and I would like to ask for some suggestions how to solve this in slurm. We're talking about a cluster that is not yet operational so there are no real legacy configs that one needs to take into account. I have two sets of physical nodes: 1. node01 - nodeXX: General Purpose Nodes. Everybody can use them 2. project_A_01 - project_A_XX: These nodes come with some restrictions regarding who can and who must not run jobs on them. Users are organized into accounts, pseudohierarchically representing workgroups / projects etc within the university. For instance, there is going to be a "physics" account with "project_blackhole", "workgroup_miller" as children. Users are associated with one or more accounts. I have three sets of accounts (each can have child accounts): 1. "General" accounts: These are allowed to use all physical nodes. 2. "ForProfit" accounts: These absolutely must not use the project_A_* nodes 3. "Project_A" accounts: Their jobs should run first and foremost on the project_A_* nodes but they are also allowed to run on the node* nodes. My first idea would be to create two partitions, one with all nodes in there and a second one with only those nodes that the "ForProfit" are allowed to use. Using "AllowAccounts" or "DenyAccounts" would implement the restriction I need. In the future, there might be more project specific nodes for other projects. I would be grateful for any alternative solution or hints, how this could be solved optimally. Thanks a lot! Thomas

5 4

Slurm version 25.05 is now available
by Tim Wickberg 29 May '25

29 May '25

We are pleased to announce the availability of Slurm 25.05. The release notes summarizing the new features, and including links to the corresponding documentation, can be found at: https://slurm.schedmd.com/release_notes.html A more extensive list of changes are available in the CHANGELOG: https://github.com/SchedMD/slurm/blob/slurm-25.05/CHANGELOG/slurm-25.05.md The Slurm documentation has also been updated to the 25.05 release: https://slurm.schedmd.com Slurm can be downloaded from: https://www.schedmd.com/download-slurm/ -- Tim Wickberg Chief Technology Officer, SchedMD LLC Commercial Slurm Development and Support

1 0

Slurm accounts managed via ansible
by Ratnasamy, Fritz 28 May '25

28 May '25

Hi, I was wondering whether there might be built in support for managing slurm accounts,users,associations in ansible. it would be nice to be able to organize accounts in a yaml style file and modify accounts settings via gitlab CI/CD. For example, in a format as such: accounts: - name: "Boss1" parent: "root" description: "Big Boos" fairshare: 20 - name: "UnderBoss1" parent: "root" description: "working for Boss1" fairshare: 1 users: -username: "user1" -username: "user2" *Fritz Ratnasamy* Data Scientist Information Technology

3 2

Account getting duplicated
by Ratnasamy, Fritz 27 May '25

27 May '25

Hi, the slurm db duplicates all our account associations. one with cluster=cluster and another where cluster=venus (which is our actual cluster). is that intended? Or should I make any changes? *Fritz Ratnasamy*Data Scientist Information Technology

2 1

Slurm Reporting Difference between sreport and sacct
by Passant Hafez 23 May '25

23 May '25

Hi all, I was wondering if someone can help explaining this discrepancy. I have different values for project gpu consumption using sreport vs sacct (+ some calculations) This is an example that shows this: sreport -t hours -T gres/gpu cluster AccountUtilizationByuser start=2025-04-01 end=2025-04-05 | grep project1234 gives 178 while sacct -n -X --allusers --accounts=project1234 --start=2025-04-01 --end=2025-04-05 -o elapsedraw,AllocTRES%80,user,partition gives 213480 billing=128,cpu=128,gres/gpu=8,mem=1000G,node=2 gpuplus 249507 billing=128,cpu=128,gres/gpu=8,mem=1000G,node=2 gpuplus 13908 billing=64,cpu=64,gres/gpu=4,mem=500G,node=1 gpuplus 9552 billing=64,cpu=64,gres/gpu=4,mem=500G,node=1 gpuplus 4 billing=16,cpu=16,gres/gpu=1,mem=200G,node=1 gpu 11 billing=16,cpu=16,gres/gpu=1,mem=200G,node=1 gpu ... I will not bore you with the full output and its calculation, but the first job alone consumed 213480 seconds/60/60 * 8 gpus that's 474.4 gpu hours which is way more than the 178 hrs reported by sreport Any clue why these are inconsistent? or how sreport calculated the 178 value? All the best, Passant

3 3

Crash in "slurmd -C" when latest NVIDIA drivers are used
by Taras Shapovalov 22 May '25

22 May '25

Hello, Does someone have idea why "slurmd -C" crashes when it unloads gpu_nrt.so with latest NVIDIA drivers (570 and 575)? We checked, there is no crash in cuda at the moment and gpu_nvml.so works fine, all nvml calls finish successfully, dlclose on gpu_nvml.so works fine. The crash does not depend whether real GPUs present or not. Steps to reproduce: 1. Install Ubuntu 24.04 2. wget https://download.schedmd.com/slurm/slurm-24.11.4.tar.bz2<https://download.schedmd.com/slurm/slurm-24.11.4.tar.bz2;> 3. tar fx ./slurm-24.11.4.tar.bz2 4. cd slurm-24.11.4 5. apt-get install cuda-12-8 hwloc libmunge-dev -y 6. ./configure 7. make && make install 8. Run "slurmd -C", or sometimes "slurmd -vvv -C" to get the crash. Stack trace: #0 0x0000155555544b2a strlen (ld-linux-x86-64.so.2 + 0x28b2a) #1 0x000015555551fc08 __GI__dl_exception_create (ld-linux-x86-64.so.2 + 0x3c08) #2 0x000015555551d298 __GI__dl_signal_error (ld-linux-x86-64.so.2 + 0x1298) #3 0x000015555551e81d _dl_close (ld-linux-x86-64.so.2 + 0x281d) #4 0x000015555551d51c __GI__dl_catch_exception (ld-linux-x86-64.so.2 + 0x151c) #5 0x000015555551d669 _dl_catch_error (ld-linux-x86-64.so.2 + 0x1669) #6 0x0000155554e97c73 _dlerror_run (libc.so.6 + 0x97c73) #7 0x0000155554e979a6 __dlclose (libc.so.6 + 0x979a6) #8 0x0000155555388a25 gpu_plugin_fini (libslurmfull.so + 0x188a25) #9 0x000015555538f2ef gres_get_autodetected_gpus (libslurmfull.so + 0x18f2ef) #10 0x0000555555564828 _print_config (slurmd + 0x10828) #11 0x0000155554e2a1ca __libc_start_call_main (libc.so.6 + 0x2a1ca) #12 0x0000155554e2a28b __libc_start_main_impl (libc.so.6 + 0x2a28b) #13 0x000055555555fc75 _start (slurmd + 0xbc75) I don't really think the problem is in gpu_nrt itself, seems the problem is in memory corruption somewhere else, but I am not sure. The issue is reproduced constantly. A Best regards, Taras

2 3

2026

2025

2024

slurm-users May 2025