[slurm-users] Re: Change primary alloc node

[Diego Zuccato via slurm-users]

Seems the perfect use case for heterogeneous jobs...

Diego

Il 31/10/2024 14:18, Davide DelVento via slurm-users ha scritto:

Another possible use case of this is a regular MPI job where the first/ controller task often uses more memory than the workers and may need to be scheduled on a higher memory node than them. I think I saw this happening in the past, but I'm not 100% sure it was in Slurm or some other scheduling system and I've lost all its references (and I would be interested to find if this is possible with Slurm, and if so how)

On Thu, Oct 31, 2024 at 1:10 AM Bhaskar Chakraborty via slurm-users <slurm-users@lists.schedmd.com <mailto:slurm-users@lists.schedmd.com>> wrote:

    Hello,

    Just to add some context here. We plan to use slurm for developing a
    sched solution which interacts with a backend system.

    Now, the backend system has pieces of h/w which require specific
    host in the allocation to be the primary/master host wherein the
    initial task would be launched, this in turn is driven by the job's
    placement orientation on the h/w itself.

    So, our primary task should launch in the asked primary host while
    secondary / remote tasks would subsequently get started on other hosts.

    Hope this brings some context to the problem as to why a specific
    host is necessary to be the starting host.

    Regards,
    Bhaskar.

    On Thursday 31 October, 2024 at 12:04:37 am IST, Laura Hild
    <l...@jlab.org <mailto:l...@jlab.org>> wrote:


    I think if you tell the list why you care which of the Nodes is
    BatchHost, they may be able to provide you with a better solution.


    ________________________________________

    Od: Bhaskar Chakraborty via slurm-users <slurm-
    us...@lists.schedmd.com <mailto:slurm-users@lists.schedmd.com>>
    Poslano: sreda, 30. oktober 2024 12:35
    Za: slurm-us...@schedmd.com <mailto:slurm-us...@schedmd.com>
    Zadeva: [slurm-users] Change primary alloc node

    Hi,

    Is there a way to change/control the primary node (i.e. where the
    initial task starts) as part of a job's allocation.

    For eg, if a job requires 6 CPUs & its allocation is distributed
    over 3 hosts h1, h2 & h3 I find that it always starts the task in 1
    particular
    node (say h1) irrespective of how many slots were available in the
    hosts.

    Can we somehow let slurm have the primary node as h2?

    Is there any C-API inside select plugin which can do this trick if
    we were to control it through the configured select plugin?

    Thanks.
    -Bhaskar.

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--
Diego Zuccato
DIFA - Dip. di Fisica e Astronomia
Servizi Informatici
Alma Mater Studiorum - Università di Bologna
V.le Berti-Pichat 6/2 - 40127 Bologna - Italy
tel.: +39 051 20 95786


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