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Preemption Scheduler Tuning Knobs
by Reed Dier 13 Oct '25

13 Oct '25

Hoping someone may be able to help demystify some questions around the scheduler and preemption decisions. I'm trying to help better predict the scheduler behavior as it pertains to preemption to create more predictable scheduling. Version is 24.11.5, OS U22.04 I have a fairly simple lo/hi partition which the same set of nodes are assigned > PartitionName=partition-lo Nodes=foo[00..NN] Default=YES MaxTime=INFINITE OverSubscribe=FORCE:1 State=UP > PartitionName=partition-hi Nodes=foo[00..NN] Default=YES MaxTime=INFINITE OverSubscribe=NO State=UP PreemptMode=OFF And then I have 2 QOSs per partition > Name Priority GraceTime Preempt PreemptMode UsageFactor MaxJobsPU MaxTRESPA MaxJobsPA > ---------------- ---------- ---------- ---------------------- ----------- ----------- --------- ------------- --------- > qos-stateless-lo 1 00:00:00 requeue 1.000000 > qos-stateful-lo 1 00:00:00 suspend 1.000000 NN cpu=NNN NNN > qos-stateful-hi 5 00:00:00 qos-state[ful,less]-lo cluster 1.000000 cpu=NNN > qos-stateless-hi 5 00:00:00 qos-state[ful,less]-lo cluster 1.000000 And the general way that it works out is that stateful jobs will typically spawn stateless jobs. Stateful jobs will get suspended, while stateless jobs will get requeued. And then there are some general guard rails around stateful jobs clogging the queue and preventing stateless jobs from scheduling and creating a deadlock, but thats not the specific issue here. > SchedulerType=sched/backfill > SelectType=select/cons_tres > SelectTypeParameters=CR_CPU_Memory > SchedulerParameters=max_rpc_cnt=500,\ > sched_min_interval=50000,\ > sched_max_job_start=300,\ > batch_sched_delay=6 > PriorityType=priority/multifactor > PreemptType=preempt/qos > PreemptMode=SUSPEND,GANG Workload is rather "high throughput", so a few settings were influenced by that <https://slurm.schedmd.com/high_throughput.html> guide. What I end up seeing is that it can take sometimes, but not always, take a while for lo jobs to be preempted by hi jobs, an example below, but if the mailing list eats images, a link to it here: https://imgur.com/a/7xVFC8a This is a rather low resolution view, as it is just a scraper running on 5 minute increments, but the blue filled area are "hi" jobs running, where the yellow are "lo" jobs running. Second image (dashed lines) are pending jobs for the same partitions. Oddly, this specific instance did not show any preemption events in the slurmctld logs, but users/admins were a bit perplexed as to why this drug on for so long, and without preemption kicking in. I was considering looking deeper into to try to better understand and predict preemption decisions: default_queue_depth partition_job_depth sched_interval sched_min_interval defer Hopefully someone can point me to some nuggets of information around this? Appreciate any pointers, Reed

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About tpology.conf
by ysaiki18＠gmail.com 12 Oct '25

12 Oct '25

Must topology.conf, like slurm.conf, be accessible to all nodes?

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Prolog error causing node to drain
by Ratnasamy, Fritz 11 Oct '25

11 Oct '25

Hi, We have a running slurm cluster and users have been submitting jobs for the past 3 months without any issues. Recently, some nodes jobs are getting drained randomly due to the reason "prolog error" Our slurm.conf has these 2 lines regarding prolog: PrologFlags=Contain,Alloc,X11 Prolog=/slurm_stuff/bin/prolog.d/prolog* Inside the prolog.d folder, there are 2 scripts which run with no errors as far as I can see but is there a way to debug why the nodes are going in draining mode once in a while because of "prolog error"? That seems to happen at random times and on random nodes. From the log file, I can see only this: Oct 06 00:57:43 pgpu008.chicagobooth.edu slurmd[3709622]: slurmd: error: prolog failed: rc:230 output:Successfully started proces> Oct 06 00:57:43 pgpu008.chicagobooth.edu slurmd[3709622]: slurmd: error: [job 20398] prolog failed status=230:0 Oct 06 00:57:43 pgpu008 slurmd[3709622]: slurmd: Job 20398 already killed, do not launch batch job Oct 06 13:06:23 pgpu008 systemd[1]: Stopping Slurm node daemon... Oct 06 13:06:23 pgpu008 slurmd[3709622]: slurmd: Caught SIGTERM. Shutting down. Oct 06 13:06:23 pgpu008 slurmd[3709622]: slurmd: Slurmd shutdown completing Currently, now the job 20398 that is getting killed in the picture above is in the state "Launch failed requeue held" after I resume the node. *Fritz Ratnasamy*Data Scientist Information Technology

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Testing Slurm on FreeBSD – Offering Feedback and Collaboration
by Rikka Göring 08 Oct '25

08 Oct '25

Hello everyone, I’d like to briefly introduce myself and share some good news. I maintain the FreeBSD port of Slurm (sysutils/slurm-wlm) and have just completed the upgrade to the latest release. Alongside this, several FreeBSD-related fixes I had been maintaining locally have now been merged upstream by SchedMD engineers, which is an encouraging step for portability. With the updated port now running reliably on FreeBSD, I can offer: - Regular build and runtime testing of Slurm on FreeBSD, - Feedback on portability patches and non-Linux code paths, - Collaboration with anyone interested in running or experimenting with Slurm on BSD systems. My goal is to help ensure that Slurm remains portable and usable on FreeBSD, and to contribute back testing and fixes where possible. If you’re working on anything that may affect portability, feel free to reach out — I’d be glad to test and provide results from the FreeBSD side. Best regards, Rikka Göring

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Unexpected missing socket error
by Ozeryan, Vladimir 07 Oct '25

07 Oct '25

Hello everyone, Not sure if you guys have heard this tune already but did anyone come across a solution for "Unexpected missing socket error". There is nothing useful in the logs but the message appears on compute nodes and slurm controller node. Thank you, Vlad Ozeryan AMDS - AB1 Linux-Support Vladimir.Ozeryan(a)jhuapl.edu Ext. 23966

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Setting GrpTRES for specific Account only for specific Partition(s)
by Paul Raines 06 Oct '25

06 Oct '25

I am trying to figure out how one can limit resources like with GrpTRES for specific accounts only for specific partitions in the cluster Lets say I have a cluster with 3 partitions Part1, Part2, and Part3 and 3 accounts Acct1, Acct2, and Acct3 I want Acct1 to be limited to 10 cpus on Part1, Acct2 to be limited to 5 cpus on Part1, and Acct3 to be limited to 8 cpus on Part1. No limits for any account on the other two partitions at present. I have tried # sacctmgr modify account Acct1 where partition=Part1 set GrpTRES=cpu=10 Modified account associations... Nothing modified I have tried creating a QOS to assign # sacctmgr add qos cpus10 # sacctmgr modify qos cpus10 set GrpTRES=cpu=10 # sacctmgr modify account Acct1 where partition=Part1 set qos=cpus10 Modified account associations... Nothing modified I cannot set a Partition QOS since that would apply to all accounts on the partition giving them the same limit I cannot just set a general Account limit (or QOS) since that would apply to all Partitions. I really don't want to have to have different Accounts for each partition so I can set Account wide limits. That would make users have to remember which Account to use with which Partiton. It looks like the following works but requires having to repeat for all users in every Account sacctmgr -i add user User1 account=Acct1 partition=Part1 \ fairshare=parent qos=cpus10 # limits on the Acct1 partition sacctmgr -i add user User1 account=Acct1 \ fairshare=parent # no limits on any other partition But in essense is not much better than having different Accounts for each partition as I now have to maintain multiple user entries per Account: one for partitios with no-limits and and additional one for each partition that needs limits. I guess at least users don't have to remember what account to use when submitting to a partition. Its seems there should be some simpler way to do this. A way to say "this is the limit for this Account on this Partion for all current users and any future users added to the Account" Am I missing something? The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Mass General Brigham Compliance HelpLine at https://www.massgeneralbrigham.org/complianceline <https://www.massgeneralbrigham.org/complianceline> . Please note that this e-mail is not secure (encrypted). If you do not wish to continue communication over unencrypted e-mail, please notify the sender of this message immediately. Continuing to send or respond to e-mail after receiving this message means you understand and accept this risk and wish to continue to communicate over unencrypted e-mail.

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cloud compute limits/budget
by Tom Sparks 03 Oct '25

03 Oct '25

I am setting up a single user slurm I have limited budget for cloud gpu compute ($40) I am wondering if slurm has ability to stop me from going over my budget? I have read the slurm's powersaving / configureless nodes guides Are they other guides I should look at?

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SRUN and SBATCH network issues on configless login node.
by Bruno Bruzzo 01 Oct '25

01 Oct '25

Hi all, first of all, sorry for my English, it's not my native language. We are currently experiencing an issue with srun and salloc on our login nodes, while sbatch works properly. slurm version 23.11.4. slurmctld runs on management node mmgt01. srun and salloc fail intermittently on login node, that means we can successfully use srun on login node from time to time, but it stops working for a while without us changing any configuration. login nodes reports the following to the user: $ srun -N 1 -n 64 --partition=gpunode --pty /bin/bash srun: job 4872 queued and waiting for resources srun: error: Security violation, slurm message from uid 202 srun: error: Security violation, slurm message from uid 202 srun: error: Security violation, slurm message from uid 202 srun: error: Task launch for StepId=4872.0 failed on node cn065: Invalid job credential srun: error: Application launch failed: Invalid job credential srun: Job step aborted uid 202 is the slurm user. On the server side, slurmctld logs show: sched: _slurm_rpc_allocate_resources JobId=4872 NodeList=(null) usec=228 sched: Allocate JobId=4872 NodeList=cn065 #CPUs=64 Partition=gpunode error: slurm_receive_msgs: [[snmgt01]:38727] failed: Zero Bytes were transmitted or received Killing interactive JobId=4872: Communication connection failure _job_complete: JobId=4872 WEXITSTATUS 1 _job_complete: JobId=4872 done step_partial_comp: JobId=4872 StepID=0 invalid; this step may have already completed _slurm_rpc_complete_job_allocation: JobId=4872 error Job/step already completing or completed We suspect it is a network issue regarding the Zero Bytes were transmitted or received. The configless system is working properly. Slurmd on login node can read changes made at slurm.conf after a scontrol reconfig. srun runs successfully from management nodes and from compute nodes. The issue is from the login node. scontrol ping always shows DOWN from login node, even when we can successfully run srun or salloc. $ scontrol ping Slurmctld(primary) at mmgt01 is DOWN We checked as well for munge consistency. mmgt and login nodes have the hostnames of their respective others on /etc/hosts. They can communicate. We would really appreciate some tips on what we could be missing. Best regards, Bruno Bruzzo System Administrator - Clementina XXI

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Re: How to make TLS and PMIx v4 work together?
by Grigory Shamov 30 Sep '25

30 Sep '25

Forgot to add: the s2n-tls comes from EPEL and is ver 1.5.10. On 2025-09-25, 11:56 AM, "Grigory Shamov via slurm-users" <slurm-users(a)lists.schedmd.com <mailto:slurm-users@lists.schedmd.com>> wrote: Caution! This message was sent from outside the University of Manitoba. Hi All, We have updated SLURM to the current 25.05.x and tried to enable TLS on it. The OS is Alma 8.10, cgroups v1, and PMIx v 4. We see that srun fails for MPI jobs across the nodes, with TLS related errors when using PMIx (the default) but passes with srun --mpi=pmi2 or with mpirun . TLSType = tls/s2n TLSParameters = ca_cert_file= (has all the certs here under /etc/slurm/certs) And the errors when using PMIx are 025-09-25T11:04:43.894] error: con_close_on_poll_error: [n388:6818(fd:15)] socket error encountered while polling: Connection reset by peer [2025-09-25T11:04:50.102] [6451416.0] error: _negotiate: s2n_negotiate() failed S2N_ERR_CERT_UNTRUSTED[335544366]: Certificate is untrusted -> Error encountered in /builddir/build/BUILD/s2n-tls-1.5.10/tls/s2n_x509_validator.c:494 (couple of these) [2025-09-25T11:05:57.878] [6451416.0] error: tls_p_recv: s2n_recv() failed S2N_ERR_CLOSED[134217728]: connection is closed -> Error encountered in /builddir/build/BUILD/s2n-tls-1.5.10/utils/s2n_io.c:37 [2025-09-25T11:05:57.883] [6451416.0] error: tls_p_send: s2n_send() failed S2N_ERR_IO[67108864]: underlying I/O operation failed, check system errno -> Error encountered in /builddir/build/BUILD/s2n-tls-1.5.10/utils/s2n_io.c:28 (couple of these) [2025-09-25T11:05:59.076] error: wrap_on_data: [unix:/var/spool/slurmd/slurmd.socket(fd:17)] on_data returned rc: Unable to proxy slurmstepd message [2025-09-25T11:05:59.076] [6451416.0] error: _stepd_send_recv_msg: slurmd was unable to proxy request message to its final destination [2025-09-25T11:05:59.878] error: _slurmd_send_recv_msg: Failed to send/recv slurmstepd message MESSAGE_TASK_EXIT using proxy_type PROXY_TO_NODE_SEND_RECV 2025-09-25T11:07:36.335] [6451416.0] error: mpi/pmix_v4: pmixp_p2p_send: n388 [0]: pmixp_utils.c:469: send failed, rc=1001, exceeded the retry limit [2025-09-25T11:07:36.335] [6451416.0] error: mpi/pmix_v4: _slurm_send: n388 [0]: pmixp_server.c:1586: Cannot send message to /var/spool/slurmd/stepd.slurm.pmix.6451416.0, size = 27679, hostlist: (null) (and couple more PMIx errors). Looks like PMIx cannot talk to their peers now ? There was no specific configuration for the certgen plugin, because SLURM documentation seems to say it is optional(?). I wonder what do we miss here to have SLURM 25.05 in with TLS enabled and PMIx working? Any advice appreciated! Thanks! -- Grigory Shamov Site Lead / HPC Specialist University of Manitoba and DRI Alliance Canada -- slurm-users mailing list -- slurm-users(a)lists.schedmd.com <mailto:slurm-users@lists.schedmd.com> To unsubscribe send an email to slurm-users-leave(a)lists.schedmd.com <mailto:slurm-users-leave@lists.schedmd.com>

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FUTURE nodes do not return to idle on slurmctld restart
by Steve Kirk 26 Sep '25

26 Sep '25

Hello, We've got a few nodes defined in our slurm.conf in 'FUTURE' state as it's a new hardware type we're working on brining into service. The nodes are currently all allocated to a dedicated partition. The partition is configured as 'state=UP'. As we've built the new nodes and started slurmd+munge, they've appeared in an idle state in the new partition as expected. All good so far. However if the slurmctld is restarted the nodes go back to being in 'FUTURE' state, and do not transition to idle, accept jobs etc. The slurm daemon on the new nodes can clearly still talk to the slurmctld, s* commands on the new nodes work as expected but remain in FUTURE state - until slurmd on each node is restarted. I could have misunderstood something about the FUTURE state but I was expecting them to go back to idle; I understand that slurmctld doesn't communicate out to nodes in FUTURE state but I at least expected them to be picked up when they communicate _in_ to the slurmctld. Is this expected behaviour or perhaps a bug? The reason I've defined the new nodes this way so I don't have to update slurm.conf and restart slurmctld as each is built, but can do that as a single job once everything is finished, however it seems less useful if they can 'disappear' from the cluster as far as users are concerned. Cheers, Steve

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2025

2024