--ntasks-per-node is meant to be used in conjunction with --nodes
option. From https://slurm.schedmd.com/sbatch.html:
*--ntasks-per-node*=</ntasks/>
Request that /ntasks/ be invoked on each node. If used with the
*--ntasks* option, the *--ntasks* option will take precedence and
the *--ntasks-per-node* will be treated as a /maximum/ count of
tasks per node. Meant to be used with the *--nodes* option...
If you don't specify --ntasks, it defaults to --ntasks=1, as Andreas
said. https://slurm.schedmd.com/sbatch.html:
*-n*, *--ntasks*=</number/>
sbatch does not launch tasks, it requests an allocation of
resources and submits a batch script. This option advises the
Slurm controller that job steps run within the allocation will
launch a maximum of /number/ tasks and to provide for sufficient
resources. The default is one task per node, but note that the
*--cpus-per-task* option will change this default.
So the correct way to specify your job is either like this
--ntasks=48
or
--nodes=1 --ntasks-per-node=48
Specifying both --ntasks-per-node and --ntasks at the same time is not
correct.
Prentice
On 2/14/19 1:09 AM, Henkel, Andreas wrote:
Hi Marcus,
What just came to my mind: if you don’t set —ntasks isn’t the default just 1? All
examples I know using ntasks-per-node also set ntasks with ntasks >=
ntasks-per-node.
Best,
Andreas
Am 14.02.2019 um 06:33 schrieb Marcus Wagner <wag...@itc.rwth-aachen.de>:
Hi all,
I have narrowed this down a little bit.
the really astonishing thing is, that if I use
--ntasks=48
I can submit the job, it will be scheduled onto one host:
NumNodes=1 NumCPUs=48 NumTasks=48 CPUs/Task=1 ReqB:S:C:T=0:0:*:*
TRES=cpu=48,mem=182400M,node=1,billing=48
but as soon as I change --ntasks to --ntasks-per-node (which should be the
same, as --ntasks=48 schedules onto one host), I get the error:
sbatch: error: CPU count per node can not be satisfied
sbatch: error: Batch job submission failed: Requested node configuration is not
available
Is there no one else, who observes this behaviour?
Any explanations?
Best
Marcus
On 2/13/19 1:48 PM, Marcus Wagner wrote:
Hi all,
I have a strange behaviour here.
We are using slurm 18.08.5-2 on CentOS 7.6.
Let me first describe our computenodes:
NodeName=ncm[0001-1032] CPUs=48 Sockets=4 CoresPerSocket=12 ThreadsPerCore=2
RealMemory=185000 Feature=skx8160,hostok,hpcwork
Weight=10541 State=UNKNOWN
we have the following config set:
$>scontrol show config | grep -i select
SelectType = select/cons_res
SelectTypeParameters = CR_CORE_MEMORY,CR_ONE_TASK_PER_CORE
So, I have 48 cores on one node. According to the manpage of sbatch, I should
be able to do the following:
#SBATCH --ntasks=48
#SBATCH --ntasks-per-node=48
But I get the following error:
sbatch: error: Batch job submission failed: Requested node configuration is not
available
Has anyone an explanation for this?
Best
Marcus
--
Marcus Wagner, Dipl.-Inf.
IT Center
Abteilung: Systeme und Betrieb
RWTH Aachen University
Seffenter Weg 23
52074 Aachen
Tel: +49 241 80-24383
Fax: +49 241 80-624383
wag...@itc.rwth-aachen.de
www.itc.rwth-aachen.de
