This isn't a dealii problem per-se. 

I am trying to run a number of simulations with different parameters of the 
same code with the underlying solver being MUMPS. I am using  *mpirun 
--cpu-set * to bind and isolate the different simulations to different 
cores (As I believe I should) 

*Profiling: *
The number of dofs are something like 262,144, the assemble function is 
called 25 times and the solve function is called 20 times. The solve 
function is using MUMPS nothing fancy is happening there. 
If I run mpirun -np2 the assemble times are 25.8 seconds and the MUMPS 
solve times are 51.7 seconds. 
If I run mpirun --cpu-set 0-1 -np 2, the assemble times are 26 seconds 
(unchanged) but the solve time are at 94.9 seconds! 
 
Is this normal and expected? 

*Maybe relevant details: *
I have 4 physical cores. I am on ubuntu. PETScVectors and  PETScWrappers::
SparseDirectMUMPS 


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