slurm: use a control node also for computing

Question

I have set up a small cluster (9 nodes) for computing in our lab. Currrently I am using one node as slurm controller, i.e. it is not being used for computing.

I would like to use it too, but I do not want to allocate all the CPUs, I would like to keep 2 CPU free for scheduling and other master-node-related tasks.

Is it possible to write something like that in slurm.conf:

NodeName=master NodeHostname=master  CPUs=10 RealMemory=192000 TmpDisk=200000 State=UNKNOWN
NodeName=node0[1-8] NodeHostname=node0[1-8]  CPUs=12 RealMemory=192000 TmpDisk=200000 State=UNKNOWN
PartitionName=mycluster Nodes=node0[1-8],master Default=YES MaxTime=INFINITE State=UP

Or do I break something? I do not want to test it without asking first because the cluster is already in production and I am worried about breaking something... In the partition here above, master is the hostname of my controller and node0[1-8] are my normal computing nodes. As you can see, not using master is a lost of 10% of CPU of the cluster...

Thanks in advance

Answer 1

Actually YES, it works.

I also added Weight=1 to nodes and Weight=2 to master, so that it get used only when the nodes are busy.

Cheers