multi core session

willimanili · February 3, 2011, 07:01

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

.

------Thread can be / is closed -----

February 3, 2011, 07:01	multi core session	#1
willimanili Member Join Date: Feb 2011 Location: DE-PB Posts: 56 Rep Power: 15	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

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February 3, 2011, 08:55		#2
RobertB Senior Member Robert Join Date: Jun 2010 Posts: 117 Rep Power: 17	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.

February 4, 2011, 13:04		#3
willimanili Member Join Date: Feb 2011 Location: DE-PB Posts: 56 Rep Power: 15	Thanks Robert for helping me. After i have disabled hyperthreading it works fine . ------Thread can be / is closed -----