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decomposePar won't break case for 8 cores

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Old   May 20, 2015, 17:48
Default decomposePar won't break case for 8 cores
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António Soares
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Hi everyone, I have an i7 processor with 8 cores (I can view them in Ubuntu System Manager) but when I configure the decomposeParDict file to distribute it over 8 cores I get an error message that says it' an uneven distribution of cores. Right now I have it running as follows:

Quote:
numberOfSubdomains 4;

method simple;

simpleCoeffs
{
n ( 2 2 1 );
delta 0.001;
}
If I try and put in 8 cores I configure it as such:

Quote:
numberOfSubdomains 8;

method simple;

simpleCoeffs
{
n ( 4 4 1 );
delta 0.001;
}
but when decomposing the case to run it I get the following error message:

Quote:
--> FOAM FATAL ERROR:
Wrong number of processor divisions in geomDecomp:
Number of domains : 8
Wanted decomposition : (4 4 1)

From function geomDecomp::geomDecomp(const dictionary& decompositionDict)
in file geomDecomp/geomDecomp.C at line 50.

FOAM exiting
I've also tried other distribution combinations such as 4 4 2 or 4 3 1 but to no avail.

Does anyone have any idea of what I might be doing wrong?

Thanks.
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Old   May 20, 2015, 18:06
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Jace
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Quote:
Originally Posted by Outbound View Post
Hi everyone, I have an i7 processor with 8 cores (I can view them in Ubuntu System Manager) but when I configure the decomposeParDict file to distribute it over 8 cores I get an error message that says it' an uneven distribution of cores. Right now I have it running as follows:



If I try and put in 8 cores I configure it as such:



but when decomposing the case to run it I get the following error message:



I've also tried other distribution combinations such as 4 4 2 or 4 3 1 but to no avail.

Does anyone have any idea of what I might be doing wrong?

Thanks.
hey,

n (4 4 1) gives your 16 cores, not 8...(you basically tell OpenFOAM to decompose into 16 regions when you only have 8 cores in your disposal.)

you need to divide in as (2 2 2), or (2 4 1), etc...
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Old   May 20, 2015, 22:04
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António Soares
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Thanks for the reply.

I guess I didn't understand the decomposition process.

I thought each digit meant the number of cores assigned to each direction (x y z) independently, I didn't really understand how the decomposition was accomplished by creating the mesh regions.

I'll try this again once the current simulation stops.

Once again, my thanks.
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decomposepar, openmpi, parallel, parallel compressible, sonicfoam

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