Ubuntu Manpage: MPI_Get_accumulate - Perform an atomic, one-sided read-and-accumulate operation

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NAME

       MPI_Get_accumulate -  Perform an atomic, one-sided read-and-accumulate operation

SYNOPSIS

       int MPI_Get_accumulate(const void *origin_addr, int origin_count, MPI_Datatype origin_datatype,
       void *result_addr, int result_count, MPI_Datatype result_datatype,
       int target_rank, MPI_Aint target_disp, int target_count,
       MPI_Datatype target_datatype, MPI_Op op, MPI_Win win)

INPUT PARAMETERS

       origin_addr
              - initial address of buffer (choice)
       origin_count
              - number of entries in origin buffer (non-negative integer)
       origin_datatype
              - datatype of each entry in origin buffer (handle)
       result_count
              - number of entries in result buffer (non-negative integer)
       result_datatype
              - datatype of each entry in result buffer (handle)
       target_rank
              - rank of target (non-negative integer)
       target_disp
              -  displacement  from  start  of window to beginning of target buffer (non-negative
              integer)
       target_count
              - number of entries in target buffer (non-negative integer)
       target_datatype
              - datatype of each entry in target buffer (handle)
       op     - reduce operation (handle)
       win    - window object (handle)

OUTPUT PARAMETERS

       result_addr
              - initial address of result buffer (choice)

NOTES

This operations is atomic with respect to other "accumulate" operations.

The get and accumulate steps are executed atomically for each basic element in the
datatype (see MPI 3.0 Section 11.7 for details). The predefined operation MPI_REPLACE
provides fetch-and-set behavior.

The origin and result buffers (origin_addr and result_addr) must be disjoint. Each
datatype argument must be a predefined datatype or a derived datatype where all basic
components are of the same predefined datatype. All datatype arguments must be constructed
from the same predefined datatype. The operation op applies to elements of that predefined
type. target_datatype must not specify overlapping entries, and the target buffer must fit
in the target window or in attached memory in a dynamic window.

Any of the predefined operations for MPI_Reduce , as well as MPI_NO_OP or MPI_REPLACE can
be specified as op. User-defined functions cannot be used. A new predefined operation,
MPI_NO_OP , is defined. It corresponds to the associative function f (a, b) = a; i.e., the
current value in the target memory is returned in the result buffer at the origin and no
operation is performed on the target buffer. MPI_NO_OP can be used only in
MPI_Get_accumulate , MPI_Rget_accumulate , and MPI_Fetch_and_op . MPI_NO_OP cannot be
used in MPI_Accumulate , MPI_Raccumulate , or collective reduction operations, such as
MPI_Reduce and others.

NOTES FOR FORTRAN

       All MPI routines in Fortran (except for MPI_WTIME  and  MPI_WTICK  )  have  an  additional
       argument  ierr  at  the  end  of  the  argument list.  ierr is an integer and has the same
       meaning as the  return  value  of  the  routine  in  C.   In  Fortran,  MPI  routines  are
       subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All  MPI  routines  (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as
       the value of the function and Fortran routines in the last argument.  Before the value  is
       returned,  the current MPI error handler is called.  By default, this error handler aborts
       the MPI  job.   The  error  handler  may  be  changed  with  MPI_Comm_set_errhandler  (for
       communicators),  MPI_File_set_errhandler  (for files), and MPI_Win_set_errhandler (for RMA
       windows).  The MPI-1 routine MPI_Errhandler_set may be used but  its  use  is  deprecated.
       The  predefined  error  handler  MPI_ERRORS_RETURN may be used to cause error values to be
       returned.  Note that MPI does not guarantee that an  MPI  program  can  continue  past  an
       error; however, MPI implementations will attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.

       MPI_ERR_BUFFER
              - Invalid buffer pointer.  Usually a null buffer where one is not valid.
       MPI_ERR_COUNT
              - Invalid count argument.  Count arguments must be non-negative; a count of zero is
              often valid.
       MPI_ERR_DISP
              -
       MPI_ERR_RANK
              - Invalid source or destination rank.  Ranks must be between zero and the  size  of
              the  communicator  minus  one;  ranks  in  a  receive  (  MPI_Recv  ,  MPI_Irecv  ,
              MPI_Sendrecv , etc.) may also be MPI_ANY_SOURCE .

       MPI_ERR_TYPE
              - Invalid datatype argument.  Additionally, this error can occur if an  uncommitted
              MPI_Datatype (see MPI_Type_commit ) is used in a communication call.
       MPI_ERR_WIN
              - Invalid MPI window object
       MPI_ERR_OTHER
              - Other error; use MPI_Error_string to get more information about this error code.