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

On 10/21/2011 04:38 AM, Hermann Fuchs wrote:

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...


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


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.