Re: [HTCondor-users] CPU Affinity in condor v8.9.1

[Greg Thain <gthain@xxxxxxxxxxx>]

On 10/17/19 11:39 AM, Shawn A Kwang wrote:
> In Condor (v8.9.1) how do I assign CPU affinity to jobs on the compute
> nodes with 24 cores? Let's say I want to limit condor to using 20 cores:
> 0-19, for users jobs. It should be noted: the cluster is using
> partitionable slots.
>
> Bigger picture: I wish to limit condors resources because the compute
> nodes run alongside the ceph-osd daemons which I want to 'reserve' a
> certain amount of RAM and CPU.


Shawn:

What I would do on this machine is set


NUM_CPUS = 20

in the htcondor config.

This will tell htcondor that it only has 20 cores to work with (but not 
which physical ones), and condor will only dole out 20 cores worth of 
work. With cgroups, if there is contention for all the cores on the 
system, the sum of the condor jobs shouldn't exceed 20 cores worth, but 
the kernel is free to pick which physical cores to use, leaving the rest 
for ceph or other system daemons.


-greg