March 2024 - slurm-users - lists.schedmd.com

Slurm billback and sreport
by Chip Seraphine 05 Mar '24

05 Mar '24

Hello, I am attempting to implement a billback model and finding myself stymied by the way that sreport handles job arrays. Basically, when a user submits a large array, their usage includes time that jobs in the back of the array spend waiting their turn. (My #1 user in “sreport user topusage” shows more “used” cpu*minutes than the cluster physically _has_ during that interval.) However, jobs that are idle pending resources are simply regarded as pending; as a result, a “polite” user who submits an array of 1000 jobs running N at a time is penalized over a user who just dumps 1000 loose jobs into the queue. This incentives my users to do exactly what I do not want! Has anyone tried to bill their users based on the results of sreport? If so, how did you work around this problem? What did you use to determine the # of CPU*Minutes that a user actually allocated on during a given interval? -- Chip Seraphine Grid Operations For support please use help-grid in email or slack. This e-mail and any attachments may contain information that is confidential and proprietary and otherwise protected from disclosure. If you are not the intended recipient of this e-mail, do not read, duplicate or redistribute it by any means. Please immediately delete it and any attachments and notify the sender that you have received it by mistake. Unintended recipients are prohibited from taking action on the basis of information in this e-mail or any attachments. The DRW Companies make no representations that this e-mail or any attachments are free of computer viruses or other defects.

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Is SWAP memory mandatory for SLURM
by John Joseph 04 Mar '24

04 Mar '24

Dear All, Good morning I do have a 4 node SLURM instance up and running. Like to know if I disable the SWAP memory, will it effect the SLURM performance Is SWAP a mandatory requirement, I have each node more RAM, if my phsicall RAM is more, is there any need for the SWAP thanks Joseph John

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What is "eligible time"
by Oren Shani 04 Mar '24

04 Mar '24

Hi All, Can someone shed some light on the exact meaning of the "eligible time" attribute in the slurm accounter, or to be more exact on the time between when the jobs becomes "eligible" to the time it actually starts to run? I understand that "eligible time" refers to the time in which the job becomes a candidate for running and that one case in which it will still not run, is that it waits for resources to become available. But are there any other conditions for a job to keep waiting at this point? For example, is fair-share scheduling considered only at this point? Many thanks, Oren

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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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