[slurm-users] job startup timeouts?

[Andy Riebs]

Hi John,

 > It's a DNS problem, isn't it?   Seriously though - how long does srun 
hostname take for a single system?

We're running nscd on all nodes, with an extremely stable list of 
users/accounts, so I think we should be good here.

"time srun hostname" reports on the order of 0.2 seconds, so at least 
single node requests are handled expediently!

Andy
------------------------------------------------------------------------
*From:* John Hearns <hearnsj at googlemail.com>
*Sent:* Friday, April 26, 2019 10:56AM
*To:* Slurm User Community List <slurm-users at lists.schedmd.com>
*Cc:*
*Subject:* Re: [slurm-users] job startup timeouts?
It's a DNS problem, isn't it?   Seriously though - how long does srun 
hostname take for a single system?


On Fri, 26 Apr 2019 at 15:49, Douglas Jacobsen <dmjacobsen at lbl.gov 
<mailto:dmjacobsen at lbl.gov>> wrote:

    We have 12,000 nodes in our system, 9,600 of which are KNL.  We can
    start a parallel application within a few seconds in most cases (when
    the machine is dedicated to this task), even at full scale. So I
    don't think there is anything intrinsic to Slurm that would
    necessarily be limiting you, though we have seen cases in the past
    where arbitrary task distribution has caused contoller slow-down
    issues as the detailed scheme was parsed.

    Do you know if all the slurmstepd's are starting quickly on the
    compute nodes?  How is the OS/Slurm/executable delivered to the node?
    ----
    Doug Jacobsen, Ph.D.
    NERSC Computer Systems Engineer
    Acting Group Lead, Computational Systems Group
    National Energy Research Scientific Computing Center
    dmjacobsen at lbl.gov <mailto:dmjacobsen at lbl.gov>

    ------------- __o
    ---------- _ '\<,_
    ----------(_)/  (_)__________________________


    On Fri, Apr 26, 2019 at 7:40 AM Riebs, Andy <andy.riebs at hpe.com
    <mailto:andy.riebs at hpe.com>> wrote:
     >
     > Thanks for the quick response Doug!
     >
     > Unfortunately, I can't be specific about the cluster size, other
    than to say it's got more than a thousand nodes.
     >
     > In a separate test that I had missed, even "srun hostname" took 5
    minutes to run. So there was no remote file system or MPI involvement.
     >
     > Andy
     >
     > -----Original Message-----
     > From: slurm-users [mailto:slurm-users-bounces at lists.schedmd.com
    <mailto:slurm-users-bounces at lists.schedmd.com>] On Behalf Of Douglas
    Jacobsen
     > Sent: Friday, April 26, 2019 9:24 AM
     > To: Slurm User Community List <slurm-users at lists.schedmd.com
    <mailto:slurm-users at lists.schedmd.com>>
     > Subject: Re: [slurm-users] job startup timeouts?
     >
     > How large is very large?  Where is the executable being started?  In
     > the parallel filesystem/NFS?  If that is the case you may be able to
     > trim start times by using sbcast to transfer the executable (and its
     > dependencies if dynamically linked) into a node-local resource, such
     > as /tmp or /dev/shm depending on your local configuration.
     > ----
     > Doug Jacobsen, Ph.D.
     > NERSC Computer Systems Engineer
     > Acting Group Lead, Computational Systems Group
     > National Energy Research Scientific Computing Center
     > dmjacobsen at lbl.gov <mailto:dmjacobsen at lbl.gov>
     >
     > ------------- __o
     > ---------- _ '\<,_
     > ----------(_)/  (_)__________________________
     >
     >
     > On Fri, Apr 26, 2019 at 5:34 AM Andy Riebs <andy.riebs at hpe.com
    <mailto:andy.riebs at hpe.com>> wrote:
     > >
     > > Hi All,
     > >
     > > We've got a very large x86_64 cluster with lots of cores on
    each node, and hyper-threading enabled. We're running Slurm 18.08.7
    with Open MPI 4.x on CentOS 7.6.
     > >
     > > We have a job that reports
     > >
     > > srun: error: timeout waiting for task launch, started 0 of
    xxxxxx tasks
     > > srun: Job step 291963.0 aborted before step completely launched.
     > >
     > > when we try to run it at large scale. We anticipate that it
    could take as long as 15 minutes for the job to launch, based on our
    experience with smaller numbers of nodes.
     > >
     > > Is there a timeout setting that we're missing that can be
    changed to accommodate a lengthy startup time like this?
     > >
     > > Andy
     > >
     > > --
     > >
     > > Andy Riebs
     > > andy.riebs at hpe.com <mailto:andy.riebs at hpe.com>
     > > Hewlett-Packard Enterprise
     > > High Performance Computing Software Engineering
     > > +1 404 648 9024
     > > My opinions are not necessarily those of HPE
     > >     May the source be with you!
     >


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