[slurm-users] Node allocation policies in cons_res and cons_tres

[nanava@luis.uni-hannover.de]

Hi, 

it seems cons_res and cons_tres allocate cpus across nodes differently.  The doc here https://slurm.schedmd.com/cpu_management.html#Overview

"When using SelectType=select/cons_res, the default allocation method across nodes is block allocation (allocate all available CPUs in a node before using another node)."

How can I get the same for the cons_tres plugin in a cluster with shared node setup ? I use Slurm 19.05.
I am aware of CR_Pack_Nodes/exclusive option, but it doesn't solve the problem.

Here is an example: (test nodes have 8 cpus each)

SelectType=select/cons_res in slurm.conf

> srun -p testpart2  -n11  hostname | sort | uniq -c
      8 test-slurm-wn03
      3 test-slurm-wn04

This is what I would expect, allocate all cpus on test-slurm-wn03 and then the rest cpus on the next node.
---------

SelectType=select/cons_tres in slurm.conf

>  srun -p testpart2  -n9  hostname | sort | uniq -c
      6 test-slurm-wn03
      5 test-slurm-wn04

Here cpus seems to be distributed evenly across nodes.

Thanks.

Best regards
Gizo