[Pw_forum] Intel MPI

Paolo Giannozzi giannozz at democritos.it
Wed Aug 18 19:28:04 CEST 2010

On Aug 18, 2010, at 19:03 , joaquin peralta wrote:

> We use a surface of Al with 81 atoms in 128 cpus using intelMPI and  
> openMPI 1.4

but not in the same way! the first job uses 8 pools of 16 processors,  
the second
1 pool of 128 processors. The first choice seems to be reasonable,  
the second
isn't, since an enormous amount of time is spent in communications  
(look at the
time spent in fft_scatter).

Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222

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