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Question about IB and Ethernet networks
by Dan Healy 04 Mar '24

04 Mar '24

Hi Fellow Slurm Users, This question is not slurm-specific, but it might develop into that. My question relates to understanding how *typical* HPCs are designed in terms of networking. To start, is it typical for there to be a high speed Ethernet *and* Infiniband networks (meaning separate switches, NICs)? I know you can easily setup IP over IB, but is IB usually fully reserved for MPI messages? I’m tempted to spec all new HPCs with only a high speed (200Gbps) IB network, and use IPoIB for all slurm comms with compute nodes. I plan on using BeeGFS for the file system with RDMA. Just looking for some feedback, please. Is this OK? Is there a better way? If yes, please share why it’s better. Thanks, Daniel Healy

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How to get usage data for a QOS
by thomas.hartmann＠th-ht.de 01 Mar '24

01 Mar '24

Hi, so, I figured out that I can give some users priority access for a specific amount of TRES by creating a qos with the GrpTRESMins property and the DenyOnLimit,NoDecay flags. This works nicely. However, I would like to know, how much of this has already been consumed and I have not yet found a way to do this. Like: How can I get the amount of TRES/TRES minutes consumed for a certain QOS? Thanks a lot! Thomas

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MinTRES in QoS and power saving
by Stefan Walter 01 Mar '24

01 Mar '24

I am running a GPU cluster where nodes are mostly off to save on electricity. I have run into the problem that if I set 'MinTRES=gres/gpu=1' in the QoS for user-account associations, waking up nodes on-demand stops working for these users. Jobs are allocated on all running nodes but if a user starts a job that would require a node to be woken up, it remains pending with 'QOSMinGRES'. In the verbose logs, such a job will show this: debug3: TRES Weight: cpu = 1.000000 * 0.000000 = 0.000000 debug3: TRES Weight: mem = 6000.000000 * 0.000000 = 0.000000 debug3: TRES Weight: energy = 0.000000 * 0.000000 = 0.000000 debug3: TRES Weight: node = 1.000000 * 0.000000 = 0.000000 debug3: TRES Weight: fs/disk = 0.000000 * 0.000000 = 0.000000 debug3: TRES Weight: vmem = 0.000000 * 0.000000 = 0.000000 debug3: TRES Weight: pages = 0.000000 * 0.000000 = 0.000000 debug3: TRES Weight: gres/gpu = 0.000000 * 1.000000 = 0.000000 debug3: TRES Weight: gres/gpu:nvidia_geforce_gtx_1080ti = 0.000000 * 0.000000 = 0.000000 debug3: TRES Weight: gres/gpumem = 0.000000 * 0.000000 = 0.000000 debug3: TRES Weight: gres/gpuutil = 0.000000 * 0.000000 = 0.000000 debug3: TRES Weighted: SUM(TRES) = 0.000000 debug2: JobId=4256 is being held, QOS local818-test min tres(gres/gpu) per job request 0 exceeds min tres limit 1 The job was started with '-G 1' or '--gres=gpu:1' but notably the TRES value for 'gres/gpu' becomes 0. For jobs that fit on the running nodes the TRES weight remains correct: debug3: TRES Weight: gres/gpu = 1.000000 * 1.000000 = 1.000000 The quick fix was to unset MinTRES for all QoS but I still would force user in some accounts to use GPUs because that is what is billed for them. Is this by design? I was not successful to find any hint that this is expected behavior. Thanks, Stefan

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pty jobs are killed when another job on the same node terminates
by Thomas Hartmann 01 Mar '24

01 Mar '24

Hi, when I start an interactive job like this: srun --pty --mem=3G -c2 bash And then I schedule and run other jobs (can be interactive or non interactive) and one of these jobs that runs on the same node terminates, the interactive job gets killed with this message: srun: error: node01.abc.at: task 0: Killed I attached our slurm config. Does anybody have an idea what is going on here or where I could look to debug? I'm quite new to slurm, so I don't know all the places to look... Thanks a lot in advance! Thomas

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GPU shards not exclusive
by Reed Dier 29 Feb '24

29 Feb '24

I seem to have run into an edge case where I’m able to oversubscribe a specific subset of GPUs on one host in particular. Slurm 22.05.8 Ubuntu 20.04 cgroups v1 (ProctrackType=proctrack/cgroup) It seems to be partly a corner case with a couple of caveats. This host has 2 different GPU types in the same host. All GPUs are configured with 6 shards/gpu. > NodeName=gpu03 CPUs=88 RealMemory=768000 Sockets=2 CoresPerSocket=22 ThreadsPerCore=2 State=UNKNOWN Feature=avx512 Gres=gpu:rtx:2,gpu:p40:6,shard:48 My gres.conf is auto-nvml, with nothing else in the file. > AutoDetect=nvml Schedule and select from slurm.conf > SchedulerType=sched/backfill > SelectType=select/cons_tres > SelectTypeParameters=CR_CPU_Memory > GresTypes=gpu,shard Here’s a copy of slurmd’s log starting up with debug logging: https://pastebin.com/fbriTAZD <https://pastebin.com/fbriTAZD> I checked there to make sure that it was allocating an even 6 shards per GPU as intended, and it did. The only thing odd about the rtx cards is that they have an NVLink bridge between them, but I wouldn’t expect that to have any impact with respect to shards. So far it only appears to manifest if anything is using the named gpu (--gres gpu:rtx:1), but not as a general gres (--gres gpu:1). It also doesn’t occur with any count of named p40 gres either, only with the rtx gres. The below was as “high” as I was able to capture it oversubscribed in very quick testing. You can see there are 2 rtx and 43 shards allocated, which should be an impossible number, if we correctly assume an rtx==6 shards, and with 48 total shards, that should reduce the available pool of shards to 36 shards. > NodeName=gpu03 Arch=x86_64 CoresPerSocket=22 > CPUAlloc=88 CPUEfctv=88 CPUTot=88 CPULoad=0.27 > AvailableFeatures=avx512 > ActiveFeatures=avx512 > Gres=gpu:p40:6(S:0),gpu:rtx:2(S:0),shard:p40:36(S:0),shard:rtx:12(S:0) > NodeAddr=gpu03 NodeHostName=gpu03 Version=22.05.8 > OS=Linux 5.4.0-164-generic #181-Ubuntu SMP Fri Sep 1 13:41:22 UTC 2023 > RealMemory=768000 AllocMem=45056 FreeMem=563310 Sockets=2 Boards=1 > State=ALLOCATED+RESERVED ThreadsPerCore=2 TmpDisk=0 Weight=1 Owner=N/A MCS_label=N/A > Partitions=gpu,gpu-prod > BootTime=2024-02-02T14:17:07 SlurmdStartTime=2024-02-14T16:28:17 > LastBusyTime=2024-02-14T16:38:03 > CfgTRES=cpu=88,mem=750G,billing=88,gres/gpu=8,gres/gpu:p40=6,gres/gpu:rtx=2,gres/shard=48 > AllocTRES=cpu=88,mem=44G,gres/gpu=2,gres/gpu:rtx=2,gres/shard=43 > CapWatts=n/a > CurrentWatts=0 AveWatts=0 > ExtSensorsJoules=n/s ExtSensorsWatts=0 ExtSensorsTemp=n/s The above is 1 rtx:2 jobs, and 43 shard:1 jobs, which is as many as I can seem to push through with the given cpu cores on the system, I expect if there were 98-100 cores I could completely oversubscribe it. If I do (1) rtx:2 + (24) shard:2 it actually limits it correctly to 36 shards, which is odd because the case that caused us to discover this was when 2 rtx:1 jobs were running for multiple days, and somehow shards got scheduled on those gpus. > AllocTRES=cpu=40,mem=20G,gres/gpu=2,gres/gpu:rtx=2,gres/shard=36 If I flip it around to shards before rtx, then I’m unable to oversubscribe it. If I add any P40 jobs before the rtx and then shard jobs, also unable to oversubscribe. This sounded familiar to Bug 16484 <https://bugs.schedmd.com/show_bug.cgi?id=16484> although they claimed it was resolved by using auto-nvml which would preclude this node. Here’s my very simple bash script that just srun's a sleep 20 so that it runs long enough to observe it. > #!/bin/bash > #rtx 2 > for((i=1;i<=1;++i)) ; > do > srun --gres gpu:rtx:2 --reservation=shardtest -J "RTX $i" sleep 20 & > done > sleep 1 > #shard 48 > for((i=1;i<=43;++i)) ; > do > srun --gres shard:1 --reservation=shardtest -J "shard $i" sleep 20 & > done > sleep 5 ; scontrol show node gpu03 Curious if anyone has any ideas beyond try a newer release? Thanks, Reed

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sbatch and cgroup v2
by Dietmar Rieder 29 Feb '24

29 Feb '24

Hi, I'm new to slrum, but maybe someone can help me: I'm trying to restrict the CPU usage to the actually requested/allocated resources using cgroup v2. For this I made the following settings in slurmd.conf: ProctrackType=proctrack/cgroup TaskPlugin=task/cgroup,task/affinity And in cgroup.conf CgroupPlugin=cgroup/v2 CgroupAutomount=yes ConstrainCores=yes ConstrainRAMSpace=yes ConstrainDevices=yes AllowedRAMSpace=98 cgroup v2 seems to be active on the compute node: # mount | grep cgroup cgroup2 on /sys/fs/cgroup type cgroup2 (rw,nosuid,nodev,noexec,relatime,nsdelegate,memory_recursiveprot) # cat /sys/fs/cgroup/cgroup.subtree_control cpuset cpu io memory pids # cat /sys/fs/cgroup/system.slice/cgroup.subtree_control cpuset cpu io memory pids Now, when I use sbatch to submit the following test script, the python script which is started from the batch script is utilizing all CPUs (96) at 100% on the allocated node, although I only ask for 4 cpus (--cpus-per-task=4). I'd expect that the task can not use more that these 4. #!/bin/bash #SBATCH --output=/local/users/appadmin/test-%j.log #SBATCH --job-name=test #SBATCH --chdir=/local/users/appadmin #SBATCH --cpus-per-task=4 #SBATCH --ntasks=1 #SBATCH --nodes=1 #SBATCH --mem=64gb #SBATCH --time=4:00:00 #SBATCH --partition=standard #SBATCH --gpus=0 #SBATCH --export #SBATCH --get-user-env=L export PATH=/usr/local/bioinf/jupyterhub/bin:/usr/local/bioinf/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/usr/local/bioinf/miniforge/condabin source .bashrc conda activate test python test.py The python code in test.py is the following using the cpu_load_generator package from [1]: #!/usr/bin/env python import sys from cpu_load_generator import load_single_core, load_all_cores, from_profile load_all_cores(duration_s=120, target_load=1) # generates load on all cores Interestingly, when I use srun to launch an interactive job, and run the python script manually, I see with top that only 4 cpus are running at 100%. And I also python errors thrown when the script tries to start the 5th process (which makes sense): File "/usr/local/bioinf/miniforge/envs/test/lib/python3.12/multiprocessing/process.py", line 314, in _bootstrap self.run() File "/usr/local/bioinf/miniforge/envs/test/lib/python3.12/multiprocessing/process.py", line 108, in run self._target(*self._args, **self._kwargs) File "/usr/local/bioinf/miniforge/envs/test/lib/python3.12/site-packages/cpu_load_generator/_interface.py", line 24, in load_single_core process.cpu_affinity([core_num]) File "/usr/local/bioinf/miniforge/envs/test/lib/python3.12/site-packages/psutil/__init__.py", line 867, in cpu_affinity self._proc.cpu_affinity_set(list(set(cpus))) File "/usr/local/bioinf/miniforge/envs/test/lib/python3.12/site-packages/psutil/_pslinux.py", line 1714, in wrapper return fun(self, *args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/bioinf/miniforge/envs/test/lib/python3.12/site-packages/psutil/_pslinux.py", line 2213, in cpu_affinity_set cext.proc_cpu_affinity_set(self.pid, cpus) OSError: [Errno 22] Invalid argument What am I missing, why are the CPU resources not restricted when I use sbatch? Thanks for any input or hint Dietmar [1]: https://pypi.org/project/cpu-load-generator/

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slurmdbd error - Symbol `slurm_conf' has different size in shared object
by Miriam Olmi 29 Feb '24

29 Feb '24

Hi all, I am having some issue with the new version of slurm 23.11.0-1. I had already installed and configured slurm 23.02.3-1 on my cluster and all the services were active and running properly. Following the instructions of the official SLURM webpage, for the moment I upgrated only the slurmdbd service. In principle the cluster should be able to work properly if the slurmdbd has a higher version with respect to slurmctld and slurmd. Unfortunately the slurmdbd service fails to start with the following status: slurmdbd.service - Slurm DBD accounting daemon Loaded: loaded (/usr/lib/systemd/system/slurmdbd.service; enabled; vendor preset: disabled) Active: failed (Result: core-dump) since Wed 2024-02-28 10:05:53 CET; 9min ago Process: 534938 ExecStart=/usr/sbin/slurmdbd -D -s $SLURMDBD_OPTIONS (code=dumped, signal=SEGV) Main PID: 534938 (code=dumped, signal=SEGV) Feb 28 10:05:53 slurm-db systemd[1]: Started Slurm DBD accounting daemon. Feb 28 10:05:53 slurm-db slurmdbd[534938]: /usr/sbin/slurmdbd: Symbol `slurm_conf' has different size in shared object, consider re-linking Feb 28 10:05:53 slurm-db systemd[1]: slurmdbd.service: Main process exited, code=dumped, status=11/SEGV Feb 28 10:05:53 slurm-db systemd[1]: slurmdbd.service: Failed with result 'core-dump'. Can anyone help me? Thanks in advance, Miriam

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salloc+srun vs just srun
by wdennis＠nec-labs.com 29 Feb '24

29 Feb '24

Hi list, In our institution, our instructions to users who want to spawn an interactive job (for us, a bash shell) have always been to do "srun ..." from the login node, which has always been working well for us. But when we had a recent Slurm training, the SchedMD folks advised us to use "salloc" and then "srun" to do interactive jobs. I tried this today, "salloc" gave me a shell on a server, the same as srun does, but then when I tried to "srun [programname]" it hung there with no output. Of course when I tried "srun [programname] &" it spawned the background job, and gave me back a prompt. Either time I had to Ctrl-C the running srun job, and got no output other than the srun/slurmstepd termination output. I think I read somewhere that directly invoking srun creates an allocation; why then would I want to do an initial salloc, and then srun? (i the case that I want a foreground program, such as a bash shell) I have surveyed some other institution's Slurm interactive jobs documentation for users, I see both examples of advice to run srun directly, or salloc and then srun. Please help me to understand how this is intended to work, and if we are "doing it wrong" :) Thanks, Will

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canonical way to run longer shell/bash interactive job (instead of srun inside of screen/tmux at front-end)?
by Josef Dvoracek 28 Feb '24

28 Feb '24

What is the recommended way to run longer interactive job at your systems? Our how-to includes starting screen at front-end node and running srun with bash/zsh inside, but that indeed brings dependency between login node (with screen) and the compute node job. On systems with multiple front-ends users need to remember the login node where they have their screen session.. Are you anybody using something more advanced and still understandable by casual user of HPC? (I know Open On Demand, but often the use of native console has certain benefits. ) cheers josef

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Enforcing relative resource restrictions in submission script
by Matthew R. Baney 28 Feb '24

28 Feb '24

Hello Slurm users, I'm trying to write a check in our job_submit.lua script that enforces relative resource requirements such as disallowing more than 4 CPUs or 48GB of memory per GPU. The QOS itself has a MaxTRESPerJob of cpu=32,gres/gpu=8,mem=384G (roughly one full node), but we're looking to prevent jobs from "stranding" GPUs, e.g., a 32 CPU/384GB memory job with only 1 GPU. I might be missing something obvious, but the rabbit hole I'm going down at the moment is trying to check all of the different ways job arguments could be set in the job descriptor. i.e., the following should all be disallowed: srun --gres=gpu:1 --mem=49G ... (tres_per_node, mem_per_node set in the descriptor) srun --gpus=1 --mem-per-gpu=49G ... (tres_per_job, mem_per_tres) srun --gres=gpu:1 --ntasks-per-gpu=5 ... (tres_per_node, num_tasks, ntasks_per_tres) srun --gpus=1 --ntasks=2 --mem-per-cpu=25G ... (tres_per_job, num_tasks, mem_per_cpu) ... Essentially what I'm looking for is a way to access the ReqTRES string from the job record before it exists, and then run some logic against that i.e., if (CPU count / GPU count) > 4 or (mem count / GPU count) > 48G, error out. Is something like this possible? Thanks, Matthew -- Matthew Baney Assistant Director of Computational Systems mbaney(a)umd.edu | (301) 405-6756 University of Maryland Institute for Advanced Computer Studies 3154 Brendan Iribe Center 8125 Paint Branch Dr. College Park, MD 20742

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