204 lines
5.1 KiB
Groff
204 lines
5.1 KiB
Groff
.TH MPI_Win_create 3 "6/5/2019" " " "MPI"
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.SH NAME
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MPI_Win_create \- Create an MPI Window object for one-sided communication
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.SH SYNOPSIS
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.nf
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int MPI_Win_create(void *base, MPI_Aint size, int disp_unit, MPI_Info info,
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MPI_Comm comm, MPI_Win * win)
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.fi
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This is a collective call executed by all processes in the group of comm. It
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returns a window object that can be used by these processes to perform RMA
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operations. Each process specifies a window of existing memory that it exposes
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to RMA accesses by the processes in the group of comm. The window consists of
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size bytes, starting at address base. In C, base is the starting address of a
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memory region. In Fortran, one can pass the first element of a memory region or
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a whole array, which must be 'simply contiguous' (for 'simply contiguous', see
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also MPI 3.0, Section 17.1.12 on page 626). A process may elect to expose no
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memory by specifying size = 0.
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.SH INPUT PARAMETERS
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.PD 0
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.TP
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.B base
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- initial address of window (choice)
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.PD 1
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.PD 0
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.TP
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.B size
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- size of window in bytes (nonnegative integer)
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.PD 1
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.PD 0
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.TP
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.B disp_unit
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- local unit size for displacements, in bytes (positive integer)
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.PD 1
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.PD 0
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.TP
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.B info
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- info argument (handle)
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.PD 1
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.PD 0
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.TP
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.B comm
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- communicator (handle)
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.PD 1
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.SH OUTPUT PARAMETERS
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.PD 0
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.TP
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.B win
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- window object returned by the call (handle)
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.PD 1
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.SH NOTES
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The displacement unit argument is provided to facilitate address arithmetic in
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RMA operations: the target displacement argument of an RMA operation is scaled
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by the factor disp_unit specified by the target process, at window creation.
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The info argument provides optimization hints to the runtime about the expected
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usage pattern of the window. The following info keys are predefined.
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.PD 0
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.TP
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.B no_locks
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- If set to true, then the implementation may assume that passive
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target synchronization (i.e.,
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.I MPI_Win_lock
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,
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.I MPI_Win_lock_all
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) will not be used on
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the given window. This implies that this window is not used for 3-party
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communication, and RMA can be implemented with no (less) asynchronous agent
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activity at this process.
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.PD 1
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.PD 0
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.TP
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.B accumulate_ordering
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- Controls the ordering of accumulate operations at the
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target. The argument string should contain a comma-separated list of the
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following read/write ordering rules, where e.g. "raw" means read-after-write:
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"rar,raw,war,waw".
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.PD 1
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.PD 0
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.TP
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.B accumulate_ops
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- If set to same_op, the implementation will assume that all
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concurrent accumulate calls to the same target address will use the same
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operation. If set to same_op_no_op, then the implementation will assume that
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all concurrent accumulate calls to the same target address will use the same
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operation or
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.I MPI_NO_OP
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\&.
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This can eliminate the need to protect access for
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certain operation types where the hardware can guarantee atomicity. The default
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is same_op_no_op.
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.PD 1
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.SH THREAD AND INTERRUPT SAFETY
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This routine is thread-safe. This means that this routine may be
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safely used by multiple threads without the need for any user-provided
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thread locks. However, the routine is not interrupt safe. Typically,
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this is due to the use of memory allocation routines such as
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.I malloc
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or other non-MPICH runtime routines that are themselves not interrupt-safe.
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.SH NOTES FOR FORTRAN
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All MPI routines in Fortran (except for
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.I MPI_WTIME
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and
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.I MPI_WTICK
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) have
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an additional argument
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.I ierr
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at the end of the argument list.
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.I ierr
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is an integer and has the same meaning as the return value of the routine
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in C. In Fortran, MPI routines are subroutines, and are invoked with the
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.I call
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statement.
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All MPI objects (e.g.,
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.I MPI_Datatype
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,
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.I MPI_Comm
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) are of type
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.I INTEGER
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in Fortran.
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.SH ERRORS
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All MPI routines (except
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.I MPI_Wtime
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and
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.I MPI_Wtick
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) return an error value;
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C routines as the value of the function and Fortran routines in the last
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argument. Before the value is returned, the current MPI error handler is
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called. By default, this error handler aborts the MPI job. The error handler
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may be changed with
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.I MPI_Comm_set_errhandler
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(for communicators),
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.I MPI_File_set_errhandler
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(for files), and
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.I MPI_Win_set_errhandler
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(for
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RMA windows). The MPI-1 routine
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.I MPI_Errhandler_set
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may be used but
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its use is deprecated. The predefined error handler
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.I MPI_ERRORS_RETURN
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may be used to cause error values to be returned.
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Note that MPI does
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.B not
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guarentee that an MPI program can continue past
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an error; however, MPI implementations will attempt to continue whenever
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possible.
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.PD 0
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.TP
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.B MPI_SUCCESS
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- No error; MPI routine completed successfully.
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.PD 1
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.PD 0
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.TP
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.B MPI_ERR_ARG
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- Invalid argument. Some argument is invalid and is not
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identified by a specific error class (e.g.,
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.I MPI_ERR_RANK
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).
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.PD 1
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.PD 0
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.TP
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.B MPI_ERR_COMM
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- Invalid communicator. A common error is to use a null
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communicator in a call (not even allowed in
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.I MPI_Comm_rank
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).
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.PD 1
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.PD 0
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.TP
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.B MPI_ERR_INFO
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- Invalid Info
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.PD 1
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.PD 0
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.TP
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.B MPI_ERR_OTHER
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- Other error; use
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.I MPI_Error_string
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to get more information
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about this error code.
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.PD 1
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.PD 0
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.TP
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.B MPI_ERR_SIZE
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-
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.PD 1
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.SH SEE ALSO
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MPI_Win_allocate MPI_Win_allocate_shared MPI_Win_create_dynamic MPI_Win_free
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.br
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