MPIinterface.ox

Low-level routines that call MPI Library routines of the same name.

Your code can use these standalone global functions to interface with the MPI library.

To ask for the MPI library to be linked in, define MPI on the command line:

oxl -DMPI mymain.ox

If the shared CFMPI library cannot be found link error will be produced.

If you do not define MPI and your program includes CFMPI then a set of "fake" versions of the routines will be included. Your program will execute serially and calls to these functions end up in messages staying in the buffer.

In most cases the interface routine takes fewer arguments than its MPI counterpart.
All messages are Ox vectors (MPI_Double).
Error codes are returned but not used.

Global variables, functions

Variables
fakebuffer	static
faketag	static
Functions
MPI_Allgather		Gather in place all messages at all nodes: interface for `MPI_Allgather()`.
MPI_Allgatherv		Gather variable length messages .
MPI_Allsum		Vector sum messages at all nodes in place.
MPI_Barrier		Make all nodes wait until this point is reached: interface to `MPI_Barrier()`.
MPI_Bcast		Broadcast a message to all nodes: interface to `MPI_Bcast()`.
MPI_Exit
MPI_Gather		Gather all buffers at the client.
MPI_Gatherv		Gather variable length messages.
MPI_Init		Initialize the MPI environment: interface for `MPI_Init()`.
MPI_Recv		Receive a message: interface for `MPI_Recv()`.
MPI_Send		Send a message: interface for `MPI_Send()`.
MPI_Setdisplace		Set the displacement amount for variable length gather.
MPI_Sum		Vector sum messages at client.

Global

fakebuffer

static decl fakebuffer

faketag

static decl faketag

MPI_Allgather

MPI_Allgather ( aBuffer , iCount )

Gather in place all messages at all nodes: interface for MPI_Allgather().

Parameters:

iCount

integer, 0 send whole buffer
otherwise send first iCount elements

MPI_Allgatherv

MPI_Allgatherv ( aBuffer )

Gather variable length messages .

Parameters:

Buffer

address

MPI_Allsum

MPI_Allsum ( aBuffer , iCount )

Vector sum messages at all nodes in place.

Parameters:

Buffer	address
iCount	integer, 0 send whole buffer otherwise send first iCount elements

MPI_Barrier

MPI_Barrier ( )

Make all nodes wait until this point is reached: interface to MPI_Barrier().

MPI_Bcast

MPI_Bcast ( aBuffer , iCount )

Broadcast a message to all nodes: interface to MPI_Bcast().

Parameters:

Buffer	address, message to broadcast to all nodes
iCount	integer, 0 send whole buffer otherwise send first iCount elements

MPI_Exit

MPI_Exit ( )

MPI_Gather

MPI_Gather ( aBuffer , iCount )

Gather all buffers at the client. Buffer at Client Node must be large enough to handle concatenation of all vectors.

Parameters:

Buffer	address
iCount	integer, 0 send whole buffer otherwise send first iCount elements

MPI_Gatherv

MPI_Gatherv ( aBuffer )

Gather variable length messages.

Parameters:

Buffer

address,

MPI_Init

MPI_Init ( aId , aNodes , aANY_TAG , aANY_SOURCE )

Initialize the MPI environment: interface for MPI_Init(). The external C routine calls MPI_Initialize() and stores key data in static C variables.

Parameters:

aId	address, the MPI Rank or ID of this node returned
aNodes	address, the number of nodes returned
aANY_TAG	address, the integer tag for `ANY_TAG` in this MPI implementation returned
aANY_SOURCE	addresss, the integer tag for `ANY_SOURCE` in this MPI implementation returned.

MPI_Recv

MPI_Recv ( aBuffer , iSource , iTag , oSource , oTag , oError )

Receive a message: interface for MPI_Recv().

Parameters:

aBuffer	address, vector message to send
iSource	integer, ID of node to receive from (can be `ANY_SOURCE`)
iTag	iteger, tag of message to receive (can be `ANY_TAG`)
oSource	address actual source ID returned
oTag	address actual tag returned
oError	address error code returned

MPI_Send

MPI_Send ( Buffer , iCount , iDest , iTag )

Send a message: interface for MPI_Send().

Parameters:

Buffer	vector message to send
iCount	integer, 0 send the whole buffer otherwise only send the first `iCount` elements
iDest	integer, ID of node to send message to
iTag	integer, tag to accompany message.

MPI_Setdisplace

MPI_Setdisplace ( iCount )

Set the displacement amount for variable length gather.

Parameters:

iCount

integer

MPI_Sum

MPI_Sum ( aBuffer , iCount )

Vector sum messages at client.

Parameters:

Buffer	address
iCount	integer, 0 send whole buffer otherwise send first iCount elements