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

[Hermann Fuchs <hermann.fuchs@xxxxxxxxxxxxxxxx>]

Hello

It seems 
COUNT_HYPERTHREAD_CPUS=FALSE
has no effect. Still all virtual hyperthreaded cores show up.
Using NUM_CPUS=4
works as expected.
However I would prefer a more automated way of detection.

Do you have any idea why COUNT_HYPERTHREAD_CPUS=FALSE could not work?
On this machine Ubuntu 11.04 64bit is employed.

Yours,
Hermann

On Fri, 2011-10-21 at 07:31 -0400, Matthew Farrellee wrote:
> 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
> 

-- 
-------------
DI Hermann Fuchs
Div. Medical Radiation Physics
Department of Radiotherapy
Med. Univ. Vienna / AKH Vienna
Währinger Gürtel 18-20
A-1090 Wien

Tel.  + 43 / 1 / 40 400 7271
Mail. hermann.fuchs@xxxxxxxxxxxxxxxx