[Pw_forum] [Pw_Forum] Parallel execution and configuration issues

[stefano de gironcoli]

Dear Konrad
    to my understanding OpenMP can be used when parallelizing within a 
multicore node. It needs shared memory between the cores so 
can't/shouldn't be used to parallelize across
different nodes. MPI does not need shared memory and can be used both 
inside a multicore node and across nodes.
    HTH
stefano

On 19/09/2016 12:01, Konrad Gruszka wrote:
>
> Dear colleagues,
>
> I'm Writing to our community to clarify once and for all issues with 
> parallel pwscf execution.
>
> By lecture of PWSCF manual, I know that there are several levels of 
> parallelization, including FFTW and more. At the same time, I'm quite 
> sure that most of beginner QE users do not have complicated clusters, 
> but are rather starting with decent multicore PC's.
>
> There are two main parallel mechanisms (known to me) namely:  MPI and 
> OpenMP. Because I'm using Ubuntu, there is free Hydra MPI software 
> (mpich) and also free OpenMP. From what I know (please correct me if 
> this is wrong) MPI software is used for parallelization within one 
> multicore PC and OpenMP is used to make parallelization between 
> several PC's.
>
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