[Pw_forum] PWSCF - In parallel (PARA_PREFIX= and PARA_POSTFIX=)

[Paolo Giannozzi]

On Friday 27 June 2003 01:10, fisicabiomolecular at yahoo.com.br wrote:
> What I must insert in:
>
> PARA_PREFIX = ???
> PARA_POSTFIX = ???
>
> To twirl in parallel?

to "twirl", I don't know: to run in parallel, you need to add
what is appropriate to your parallel environment. From the
manual (modified yesterday):
-------------------------------------------------
Parallel execution is strongly system- and installation-dependent.
Typically one has to specify:
\begin{itemize}
\item a launcher program, such as {\tt poe}, {\tt mpirun}, {\tt mpiexec};
\item the number of processors, typically as an option to the launcher
      program, but sometimes {\em after} the program to be executed;
\item the program to be executed, with the proper path if needed:
      for instance, {\tt pw.x}, or {\tt ./pw.x}, or
      {\tt \$(HOME)/bin/pw.x}, or whatever applies;
\item the number of ``pools'' into which processors are to be grouped
     (see Section ``Parallelization Issues'' below for an explanation
      of what a pool is).
\end{itemize}
The last item is optional and is read by the code. The first and second
items are machine- and installation-dependent, and may be different
for interactive and batch execution.

Let us consider the case of execution of {\tt pw.x} on 16 processors 
divided into 8 pools (2 processors each). Some typical cases:
\begin{itemize}
\item IBM SP machines, batch: \\
{\tt pw.x -npool 8 < input}
\item IBM SP machines, interactive, using {\tt poe}: \\
{\tt poe pw.x -procs 16 -npool 8 < input} \\
\item IBM SP machines, interactive, alternative: \\
{\tt pw.x -npool 8 < input} \\
where environment variable {\tt NPROC} is set to 16,
{\tt MP\_HOSTFILE} to the file containing a list of processors.
\item SGI Origin, PC clusters using {\tt mpirun}: \\
{\tt mpirun -np 16 pw.x -npool 8 < input} .
\item Cray T3E (old): \\
{\tt mpprun -n 16 pw.x -npool 8 < input} .
\\item PC clusters using  {\tt mpiexec}: \\
{\tt mpiexec -n 16 pw.x -npool 8 < input} .
\end{itemize}
-------------------------------------------------

Paolo
-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
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