Re: [HTCondor-devel] cpu affinity and partitionable slots

[Dan Bradley <dan@xxxxxxxxxxxx>]

On 11/12/12 9:01 AM, Greg Thain wrote:
> On 11/09/2012 04:49 PM, Dan Bradley wrote:
> > 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.
> Dan:
>
> We certainly want to have a solution for cpu-limiting in a 
> partitionable slot world.  One question is whether all of your 
> clusters are ready for cgroups?  I was surprised to learn this week 
> that LIGO has worked around all of their Debian-related cgroup problems.
> All things being equal, I would prefer to do this with cgroups, as I 
> don't like having to lock a job to a particular physical CPU.
If I understand correctly, cgroups could be used to limit the share of 
the cpu for a job while still giving the OS flexibility to schedule 
tasks on whichever cores it deems best.  If that is right, then I'd 
prefer to have support for that instead of cpu affinity, even if there 
is a window of time before all of our resources can take advantage of it.
--Dan