113 строки
3.3 KiB
Plaintext
113 строки
3.3 KiB
Plaintext
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.\" -*- nroff -*-
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.\" Copyright (c) 2015 University of Houston. All rights reserved.
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.\" Copyright (c) 2015 Mellanox Technologies, Inc.
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.\" $COPYRIGHT$
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.de Vb
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.ft CW
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.nf
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..
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.de Ve
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.ft R
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.fi
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..
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.TH "SHMEM\\_BARRIER" "3" "#OMPI_DATE#" "#PACKAGE_VERSION#" "#PACKAGE_NAME#"
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.SH NAME
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shmem_barrier \- Performs a barrier operation on a subset of processing elements (PEs).
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.SH SYNOPSIS
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C or C++:
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.Vb
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#include <mpp/shmem.h>
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void shmem_barrier(int PE_start, int logPE_stride, int PE_size,
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long *pSync);
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.Ve
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Fortran:
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.Vb
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INCLUDE "mpp/shmem.fh"
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INTEGER PE_start, logPE_stride, PE_size
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INTEGER pSync(SHMEM_BARRIER_SYNC_SIZE)
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CALL SHMEM_BARRIER(PE_start, logPE_stride, PE_size, pSync)
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.Ve
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.SH DESCRIPTION
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The shmem_barrier routine does not return until the subset of PEs specified by
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\fBPE_start\fP,
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\fBlogPE_stride\fP
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and \fBPE_size\fP,
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has entered this routine at the
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same point of the execution path.
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.PP
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As with all SHMEM collective routines, each of these routines assumes that only PEs in the
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active set call the routine. If a PE not in the active set calls a SHMEM collective routine,
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undefined behavior results.
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.PP
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The arguments are as follows:
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.TP
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PE_start
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The lowest virtual PE number of the active set of PEs. PE_start must be of
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type integer. If you are using Fortran, it must be a default integer value.
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.TP
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logPE_stride
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The log (base 2) of the stride between consecutive virtual PE numbers in
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the active set. logPE_stride must be of type integer. If you are using Fortran, it must be a
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default integer value.
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.TP
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PE_size
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The number of PEs in the active set. PE_size must be of type integer. If you
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are using Fortran, it must be a default integer value.
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.TP
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pSync
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A symmetric work array. In C/C++, pSync must be of type int and size
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_SHMEM_BARRIER_SYNC_SIZE. In Fortran, pSync must be of type integer and size
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SHMEM_BARRIER_SYNC_SIZE. If you are using Fortran, it must be a default integer type.
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Every element of this array must be initialized to 0 before any of the PEs in the active set enter
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shmem_barrier the first time.
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.PP
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The values of arguments PE_start, logPE_stride, and PE_size must be equal on all PEs in the
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active set. The same work array must be passed in pSync to all PEs in the active set.
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.PP
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shmem_barrier ensures that all previously issued local stores and previously issued remote
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memory updates done by any of the PEs in the active set (by using SHMEM calls, for
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example \fIshmem_put\fP(3))
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are complete before returning.
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.PP
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The same pSync array may be reused on consecutive calls to shmem_barrier if the same
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active PE set is used.
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.PP
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.SH NOTES
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The term symmetric is defined in \fIintro_shmem\fP(3)\&.
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.PP
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If the pSync array is initialized at run time, be sure to use some type of synchronization, for
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example, a call to \fIshmem_barrier_all\fP(3),
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before calling shmem_barrier for the first
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time.
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.PP
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If the active set does not change, shmem_barrier can be called repeatedly with the same
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pSync array. No additional synchronization beyond that implied by shmem_barrier itself is
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necessary in this case.
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.PP
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.SH EXAMPLES
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C/C++ example:
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.Vb
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shmem_barrier(PE_start, logPE_stride, size, pSync);
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.Ve
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Fortran example:
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.Vb
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INTEGER PSYNC(SHMEM_BARRIER_SYNC_SIZE)
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INTEGER PE_START, LOGPE_STRIDE, PE_SIZE, PSYNC
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DATA PSYNC /SHMEM_BARRIER_SYNC_SIZE*0/
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CALL SHMEM_BARRIER(PE_START, LOGPE_STRIDE, PE_SIZE, PSYNC)
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.Ve
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.SH SEE ALSO
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\fIintro_shmem\fP(3),
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\fIshmem_barrier_all\fP(3)
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