[HTCondor-devel] cpu affinity and partitionable slots

[Dan Bradley <dan@xxxxxxxxxxxx>]

Hi all

I was thinking about the lack of support in Condor for setting cpu 
affinity with partitionable slots in a useful way.  We do this on our 
non-partitionable slots to avoid the inevitable accidents where jobs try 
to use the whole machine from a single-core slot.  We'd like to be able 
to do it on the partitionable slots.
My first question is whether cpu shares in cgroups make the above 
use-case of cpu affinity obsolete.
If not, then it would be really nice to have cpu affinity working in the 
partitionable slot world.  The problem is that all dynamic slots under a 
single partitionable slot get assigned to the same set of cpus.  It 
seems to me that the startd needs to manage the partitioning of the cpu 
set when it creates the dynamic slots.
Are there plans for generic support for this sort of non-fungible 
resource partitioning?  Implementing this specific case does not sound 
very hard, as long as we (at least initially) just use a first-fit 
strategy and do not worry about optimizing which cores go best together 
in case of multi-core jobs.  I think it could even be done without 
adding any new configuration knobs (gasp).
Thoughts?

--Dan