Specify number of CPUs for a job on SLURM - slurm

Question

I would like to run multiple jobs on a single node on my cluster. However, when I submit a job, it takes all available CPUs and so remaining jobs are queued. As an example, I made a script that request few resources and submit two jobs that are supposed to run at the same time.
#! /bin/bash
variable=$(seq 0 1 1)
for l in ${variable}
do
run_thread="./run_thread.sh"
cat << EOF > ${run_thread}
#! /bin/bash
#SBATCH -p normal
#SBATCH --nodes 1
#SBATCH --cpus-per-task 1
#SBATCH --ntasks 1
#SBATCH --threads-per-core 1
#SBATCH --mem=10G
sleep 120
EOF
sbatch ${run_thread}
done
However, one job is running and the other user is pending:
JOBID PARTITION NAME USER ST TIME NODES NODELIST(REASON)
57 normal run_thre user PD 0:00 1 (Resources)
56 normal run_thre user R 0:02 1 node00
The cluster only has one node with 4 sockets with 12 cores and 2 threads each. the output of command scontrol show jobid #job is the following:
JobId=56 JobName=run_thread.sh
UserId=user(1002) GroupId=user(1002) MCS_label=N/A
Priority=4294901755 Nice=0 Account=(null) QOS=(null)
JobState=RUNNING Reason=None Dependency=(null)
Requeue=1 Restarts=0 BatchFlag=1 Reboot=0 ExitCode=0:0
RunTime=00:00:51 TimeLimit=UNLIMITED TimeMin=N/A
SubmitTime=2018-03-24T15:34:46 EligibleTime=2018-03-24T15:34:46
StartTime=2018-03-24T15:34:46 EndTime=Unknown Deadline=N/A
PreemptTime=None SuspendTime=None SecsPreSuspend=0
Partition=normal AllocNode:Sid=node00:13047
ReqNodeList=(null) ExcNodeList=(null)
NodeList=node00
BatchHost=node00
NumNodes=1 NumCPUs=48 NumTasks=1 CPUs/Task=1 ReqB:S:C:T=0:0:*:1
TRES=cpu=48,mem=10G,node=1
Socks/Node=* NtasksPerN:B:S:C=0:0:*:* CoreSpec=*
MinCPUsNode=1 MinMemoryNode=10G MinTmpDiskNode=0
Features=(null) DelayBoot=00:00:00
Gres=(null) Reservation=(null)
OverSubscribe=NO Contiguous=0 Licenses=(null) Network=(null)
Command=./run_thread.sh
WorkDir=/home/user
StdErr=/home/user/slurm-56.out
StdIn=/dev/null
StdOut=/home/user/slurm-56.out
Power=
And the output of scontrol show partition is:
PartitionName=normal
AllowGroups=ALL AllowAccounts=ALL AllowQos=ALL
AllocNodes=ALL Default=YES QoS=N/A
DefaultTime=NONE DisableRootJobs=NO ExclusiveUser=NO GraceTime=0 Hidden=NO
MaxNodes=UNLIMITED MaxTime=UNLIMITED MinNodes=1 LLN=NO MaxCPUsPerNode=UNLIMITED
Nodes=node00
PriorityJobFactor=1 PriorityTier=1 RootOnly=NO ReqResv=NO OverSubscribe=YES:4
OverTimeLimit=NONE PreemptMode=OFF
State=UP TotalCPUs=48 TotalNodes=1 SelectTypeParameters=NONE
DefMemPerNode=UNLIMITED MaxMemPerNode=UNLIMITED
There is something I don't get with the SLURM system. How can I use only 1 CPU per job and run 48 jobs on the node at the same time?

Answer 1

Slurm is probably configured with
SelectType=select/linear
which means that slurm allocates full nodes to jobs and does not allow node sharing among jobs.
You can check with
scontrol show config | grep SelectType
Set a value of select/cons_res to allow node sharing.