Difference between processor CPU core in parallel launch

woodwick · October 31, 2013, 20:53

Hello,

I don't understand very well the difference between "core" and "processor", so I am a bit confused in determining what is the maximum number of "processors" that I should consider for a parallel launch.

I was testing a machine with:
16 processors Intel(R) Xeon(R) CPU E5-2680 0 @ 2.70Ghz

therefore in my openFOAM test case I tried a simulation with 16 processors.

Code:

runParallel rhoSimpleFoam 16

And I was thinking: "16 is the maximum number allowed".

Then I realized that each CPU E5-2680 has apparently 8 cores:
http://ark.intel.com/products/64583/

does it mean that I can consider each core as a "processor" and run an analysis in parallel with 16 * 8 = 128 "processors" ?
Now I was testing

Code:

runParallel rhoSimpleFoam 128

the analysis runs, OpenFOAM creates the 128 processors directories, no error.

Can I conclude:

max "processor" number for parallel analysis = number of multicore processors * number of cores for each processor

is it right?

Regards

Ale

TMG · November 16, 2013, 12:14

All modern cpu's today have more than one core. Each core can be considered a processor. If you have 16 cpu's and each cpu is built from 8 cores then you should be able to run 16x8=128 parallel processes.

October 31, 2013, 20:53	Difference between processor CPU core in parallel launch	#1
woodwick New Member Alessandro Join Date: Feb 2013 Location: Italia Posts: 15 Rep Power: 13	Hello, I don't understand very well the difference between "core" and "processor", so I am a bit confused in determining what is the maximum number of "processors" that I should consider for a parallel launch. I was testing a machine with: 16 processors Intel(R) Xeon(R) CPU E5-2680 0 @ 2.70Ghz therefore in my openFOAM test case I tried a simulation with 16 processors. Code: runParallel rhoSimpleFoam 16 And I was thinking: "16 is the maximum number allowed". Then I realized that each CPU E5-2680 has apparently 8 cores: http://ark.intel.com/products/64583/ does it mean that I can consider each core as a "processor" and run an analysis in parallel with 16 * 8 = 128 "processors" ? Now I was testing Code: runParallel rhoSimpleFoam 128 the analysis runs, OpenFOAM creates the 128 processors directories, no error. Can I conclude: max "processor" number for parallel analysis = number of multicore processors * number of cores for each processor is it right? Regards Ale

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November 16, 2013, 12:14		#2
TMG Member Join Date: Mar 2009 Posts: 44 Rep Power: 17	All modern cpu's today have more than one core. Each core can be considered a processor. If you have 16 cpu's and each cpu is built from 8 cores then you should be able to run 16x8=128 parallel processes.