Re: [Condor-users] How to filter out hyperthreading CPU cores

[Matthew Farrellee <matt@xxxxxxxxxx>]

On 10/21/2011 04:38 AM, Hermann Fuchs wrote:
> Hello
>
> In our condor cluster we have several workstations configured to use
> hyperthreading (e.g. virtual CPU cores from INTEL CPUs).
> Condor seems to recognise virtual hyperthreaded CPU cores as real ones
> and evenly divides recources.
>
> For example a workstation with a four core Intel CPU would then appear
> as an eight core workstation, which we would like to avoid.
>
> We do not want to use such virtual CPU cores but can not enforce their
> hardware sided (e.g in the BIOS) deactivation. Is there a way that
> condor somehow "filters" them out and announces only real CPU cores?
>
> Can condor distinguish real cores from virtual ones?
> I suppose manually declaring 4 CPU cores may not work because all 4
> declared cores might be running on virtual cores...
>
> Yours,
> Hermann

You could configure NUM_CPUS=4, but try COUNT_HYPERTHREAD_CPUS=FALSE first.

http://www.cs.wisc.edu/condor/manual/v7.6/3_3Configuration.html#17736

COUNT_HYPERTHREAD_CPUS
    This macro controls how Condor sees hyper threaded processors. When 
set to True (the default), it includes virtual CPUs in the default value 
of NUM_CPUS. On dedicated cluster nodes, counting virtual CPUs can 
sometimes improve total throughput at the expense of individual job 
speed. However, counting them on desktop workstations can interfere with 
interactive job performance.

Best,


matt