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MPI 2.0 features supported
One-sided communication
One-sided communication
Message-passing communication involves transferring data from the
sending process to the receiving process and synchronization of the
sender and receiver.
Remote memory access and one-sided communication extend the
communication mechanism of MPI by separating the communication and
synchronization functions. One process specifies all communication
parameters both for the sending side and the receiving side. This mode of
communication is best for applications with dynamically changing data
access patterns where data distribution is fixed or slowly changing. Each
process can compute what data it needs to access or update at other
processes. Processes in such applications, however, may not know which
data in their memory needs to be accessible by remote processes or even
the identity of these remote processes.
In this case, applications can open windows in their memory space that
are accessible by remote processes.
HP MPI supports a subset of the MPI 2.0 one-sided communication
functionality:
• Window creation—The initialization process that allows each process
in an intracommunicator group to specify, in a collective operation, a
window in its memory that is made accessible to remote processes.
The window-creation call returns an opaque object that represents
the group of processes that own and access a set of windows, and the
attributes of each window, as specified by the initialization call.
HP MPI supports the MPI_Win_create and the MPI_Win_free
functions. MPI_Win_Create is a collective call executed by all
processes in a group. It returns a window object that can be used by
these processes to perform remote memory access operations.
MPI_Win_free is also a collective call, and frees the window object
created by MPI_Win_create, and returns a null handle.
• Window attributes—HP MPI supports the MPI_Win_get_group
function. MPI_Win_get_group returns a duplicate of the group of
the communicator used to create the window, that is, the processes
that share access to the window.
Appendix C
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