.\" -*- nroff -*-
.\" Copyright (c) 2015      University of Houston.  All rights reserved.
.\" Copyright (c) 2015      Mellanox Technologies, Inc.
.\" $COPYRIGHT$
.de Vb
.ft CW
.nf
..
.de Ve
.ft R

.fi
..
.TH "SHMEM\\_INIT" "3" "Jan 31, 2017" "2.0.2" "Open MPI"
.SH NAME

shmem_init, start_pes
\- Allocates a block of memory from the symmetric heap.
.SH SYNOPSIS

C or C++:
.Vb
void shmem_init(void);
void start_pes(int npes);
.Ve
Fortran:
.Vb
CALL SHMEM_INIT()
CALL START_PES(npes)
.Ve
.SH DESCRIPTION

The start_pes routine should be the first statement in a SHMEM parallel program.
.PP
The start_pes routine accepts the following argument:
.TP
npes
Unused. Should be set to 0.
.PP
This routine initializes the SHMEM API, therefore it must be called before calling any
other SHMEM routine.
This routine is responsible inter alia for setting up the symmetric heap on the calling PE, and
the creation of the virtual PE numbers. Upon successful return from this routine, the calling PE
will be able to communicate with and transfer data to other PEs.
.PP
Multiple calls to this function are not allowed.
.PP
For an overview of programming with SHMEM communication routines, example SHMEM
programs, and instructions for compiling SHMEM programs, see the \fIintro_shmem\fP(3)
man page.
.SH EXAMPLES

This is a simple program that calls \fIshmem_integer_put\fP(3):
.Vb
PROGRAM PUT
  INCLUDE "mpp/shmem.fh"

  INTEGER TARG, SRC, RECEIVER, BAR
  COMMON /T/ TARG
  PARAMETER (RECEIVER=1)

  CALL SHMEM_INIT()
  IF (MY_PE() .EQ. 0) THEN
    SRC = 33
    CALL SHMEM_INTEGER_PUT(TARG, SRC, 1, RECEIVER)
  ENDIF
  CALL SHMEM_BARRIER_ALL ! SYNCHRONIZES SENDER AND RECEIVER
  IF (MY_PE() .EQ. RECEIVER) THEN
    PRINT *,'PE ', MY_PE(),' TARG=',TARG,' (expect 33)'
  ENDIF
END
.Ve
.SH NOTES

If the start_pes call is not the first statement in a program, unexpected results may occur on
some architectures.
.SH SEE ALSO

\fIintro_shmem\fP(3),
\fIshmem_barrier\fP(3),
\fIshmem_barrier_all\fP(3),
\fIshmem_put\fP(3),
\fImy_pe\fP(3I),
\fIshmem_n_pes\fP(3I)