[slurm-users] How should I do so that jobs are allocated to the thread and not to the core ?

[Jean-mathieu CHANTREIN]

Hello, 

Most jobs of my users are single-thread. I have multithreaded processors. The jobs seem to reserve 2 logical CPU (1 core=2 CPU (2 threads)) whereas it only uses 1 logical CPU(1 thread). Nevertheless, my slurm.conf file indicates: 

[...] 
SelectType = select / cons_res 
SelectTypeParameters = CR_CPU 
FastSchedule = 1 
[...] 
NodeName = DEFAULT Boards = 1 SocketsPerBoard = 2 CoresPerSocket = 18 ThreadsPerCore = 2 RealMemory = 128000 

And here is an excerpt from the output of a job running on this type of node: 
$ scontrol show job idjob 
[...] 
NumNodes=1 NumCPUs=1 NumTasks=1 CPUs/Task=1 ReqB:S:C:T=0:0:*:* 
TRES=cpu=1,mem=200M,node=1,billing=1 
Socks/Node=* NtasksPerN:B:S:C=0:0:*:* CoreSpec=* 
MinCPUsNode=1 MinMemoryCPU=200M MinTmpDiskNode=0 
Features=(null) DelayBoot=00:00:00 
OverSubscribe=OK Contiguous=0 Licenses=(null) Network=(null) 

But with [ https://github.com/OleHolmNielsen/Slurm_tools/tree/master/pestat | pestat  ] , I can see my node use 72/72 CPU but have only 36 job running like this one. 

How should I do so that jobs are allocated to the thread and not to the core ? 

Best regards. 

Jean-Mathieu 

	
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