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willimanili February 3, 2011 07:01

multi core session
 
Hi everybody,

i am working with CCM+ on a intel quad core linux workstation, and have one star ccm+ licence and also licence for using two cores for solving. But i am a little bit confused, because when i solve a simulation, i can see on my system monitor that only two of the eight virtuell CPU's are running.
For the people who are wondering now, why there are 8 CPU's on a quad core, this is because every physical CPU is diveded into 2 virtuell CPU's.
So that means, although i have a two core licence star cmm+ is solving on two virtuell CPU's that means just one physical CPU.

I have already talked to the support,but they can't really help me.

I would like to know if anybody else have made these experience and maybe somebody know why it is like this.

Best regards,
Max

RobertB February 3, 2011 08:55

The OS should schedule the two threads onto two different physical cores. Some OSes can get confused as to what is/is not a real CPU (some Linux versions). In this case if you turn off the hyperthreading in the BIOS then all cores are real and the problem goes away.

I doubt that most CAE/HPC applications are heavily threaded enough to really gain from hyperthreading and thus it is no real loss.

willimanili February 4, 2011 13:04

Thanks Robert for helping me. After i have disabled hyperthreading it works fine :).


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