truebutterfly.c File Reference

Implementation of routines for butterfly-like communication scheme, with classic pair wise butterfly scheme. More...

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Functions
int	truebutterfly_init (int *indices, int count, int **R, int *nR, int **S, int *nS, int **com_indices, int *com_count, int steps, MPI_Comm comm)
	Initialize tables for butterfly-like communication scheme (true means pair wise) This routine set up needed tables for the butterfly communication scheme. Sending and receiving tabs should be well allocated(at least size of number of steps in butterfly scheme). Double pointer are partially allocated, the last allocation is performed inside the routine. com_indices and com_count are also allocated inside the routine, thus they are passing by reference. They represent indices which have to be communicated an their number. Algotithm is based 2 parts. The first one identify intersection between processors indices, using 3 successives butterfly communication schemes : bottom up, top down, and top down again. The second part works locally to build sets of indices to communicate. More...
int	truebutterfly_reduce (int **R, int *nR, int nRmax, int **S, int *nS, int nSmax, double *val, int steps, MPI_Comm comm)
	Perform a sparse sum reduction (or mapped reduction) using a butterfly-like communication scheme (true means pairwise) More...

Detailed Description

Implementation of routines for butterfly-like communication scheme, with classic pair wise butterfly scheme.

Note

Copyright (c) 2010-2012 APC CNRS Université Paris Diderot. This program is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, see http://www.gnu.org/licenses/lgpl.html

For more information about ANR MIDAS'09 project see http://www.apc.univ-paris7.fr/APC_CS/Recherche/Adamis/MIDAS09/index.html

ACKNOWLEDGMENT: This work has been supported in part by the French National Research Agency (ANR) through COSINUS program (project MIDAS no. ANR-09-COSI-009).

Author

Radek Stompor

Date

October 2012

Definition in file truebutterfly.c.

Function Documentation

truebutterfly_init()

int truebutterfly_init	(	int *	indices,
		int	count,
		int **	R,
		int *	nR,
		int **	S,
		int *	nS,
		int **	com_indices,
		int *	com_count,
		int	steps,
		MPI_Comm	comm
	)

Initialize tables for butterfly-like communication scheme (true means pair wise) This routine set up needed tables for the butterfly communication scheme. Sending and receiving tabs should be well allocated(at least size of number of steps in butterfly scheme). Double pointer are partially allocated, the last allocation is performed inside the routine. com_indices and com_count are also allocated inside the routine, thus they are passing by reference. They represent indices which have to be communicated an their number. Algotithm is based 2 parts. The first one identify intersection between processors indices, using 3 successives butterfly communication schemes : bottom up, top down, and top down again. The second part works locally to build sets of indices to communicate.

Parameters

indices	set of indices(monotony) handle by a process.
count	number of elements
R	pointer to receiving maps
nR	array of number of elements in each receiving map
S	pointer to sending maps
nS	array of number of elements in each sending map
com_indices	set of indices(monotony) communicated by a process
com_count	number of elements
steps	number of communication exchange in the butterfly scheme
comm	MPI communicator

Returns

0 if no error

Definition at line 51 of file truebutterfly.c.

truebutterfly_reduce()

int truebutterfly_reduce	(	int **	R,
		int *	nR,
		int	nRmax,
		int **	S,
		int *	nS,
		int	nSmax,
		double *	val,
		int	steps,
		MPI_Comm	comm
	)

Perform a sparse sum reduction (or mapped reduction) using a butterfly-like communication scheme (true means pairwise)

Parameters

R	pointer to receiving maps
nR	array of number of elements in each receiving map
nRmax	maximum size of received message
S	pointer to sending maps
nS	array of number of elements in each sending map
nSmax	maximum size of sent message
val	set of values (typically values associated to communicated indices)
steps	number of communication exchange in the butterfly scheme
comm	MPI communicator

Returns

0 if no error

Definition at line 248 of file truebutterfly.c.