#include "ghost/config.h"
#include "ghost/core.h"
#include "ghost/types.h"
#include "ghost/util.h"
#include "ghost/context.h"
#include "ghost/locality.h"
#include "ghost/bincrs.h"
#include "ghost/matrixmarket.h"
#include "ghost/log.h"
#include "ghost/omp.h"
#include "ghost/machine.h"
#include "ghost/bench.h"
#include "ghost/map.h"
#include <float.h>
#include <math.h>

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Functions
ghost_error	ghost_context_create (ghost_context **context, ghost_gidx gnrows, ghost_gidx gncols, ghost_context_flags_t context_flags, ghost_mpi_comm comm, double weight)
	Create a context. More...

ghost_error	ghost_context_string (char *str, ghost_context context)
	Create a string containing information on the context. More...

void	ghost_context_destroy (ghost_context *context)
	Free the context's resources. More...

ghost_error	ghost_context_comm_init (ghost_context ctx, ghost_gidx col_orig, ghost_sparsemat mat, ghost_lidx col, ghost_lidx *nhalo)
	Assemble communication information in the given context. More...

char *	ghost_context_workdist_string (ghost_context_flags_t flags)
	Get the name of the work distribution scheme. More...

ghost_map *	ghost_context_map (const ghost_context *ctx, const ghost_maptype mt)
	Get the context's map with the given map type. More...

ghost_map *	ghost_context_other_map (const ghost_context *ctx, const ghost_maptype mt)
	Get the context's map which does not have the given map type. More...

ghost_map *	ghost_context_max_map (const ghost_context *ctx)
	Get the largest map of the context. More...

ghost_error	ghost_context_set_map (ghost_context ctx, ghost_maptype which, ghost_map map)
	Set a context's map. More...

Function Documentation

ghost_error ghost_context_comm_init	(	ghost_context *	ctx,
		ghost_gidx *	col_orig,
		ghost_sparsemat *	mat,
		ghost_lidx *	col,
		ghost_lidx *	nhalo
	)

Assemble communication information in the given context.

Parameters

[in,out]	ctx	The context.
[in]	col_orig	The original column indices of the sparse matrix which is bound to the context.
[out]	col	The compressed column indices of the sparse matrix which is bound to the context.
[out]	nhalo	The number of halo elements.

Returns: GHOST_SUCCESS on success or an error indicator.

The following fields of ghost_context are being filled in this function: wishes, wishlist, dues, duelist, hput_pos, wishpartners, nwishpartners, duepartners, nduepartners. Additionally, the columns in col_orig are being compressed and stored in col.

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ghost_error ghost_context_create	(	ghost_context **	context,
		ghost_gidx	gnrows,
		ghost_gidx	gncols,
		ghost_context_flags_t	flags,
		ghost_mpi_comm	comm,
		double	weight
	)

Create a context.

Parameters

[out]	context	Where to store the created context.
[in]	gnrows	The global number of rows for the context. If gnrows is 0 a valid matrix file path has to be provided in the argument matrixSource from which the number of rows will be read.
[in]	gncols	The global number of columns for the context. If gncols is 0 a valid matrix file path has to be provided in the argument matrixSource from which the number of columns will be read.
[in]	flags	Flags to the context.
[in]	matrixSource	The sparse matrix source.
[in]	srcType	The type of the sparse matrix source.
[in]	comm	The MPI communicator in which the context is present.
[in]	weight	This influences the work distribution amon ranks. If set to 0., it is automatically determined.

Returns: GHOST_SUCCESS on success or an error indicator.

The matrix source can either be one of ghost_sparsemat_src. The concrete type has to be specified in the srcType parameter. It must not be GHOST_SPARSEMAT_SRC_NONE in the following cases:

If gnrows or gncols are given as less than 1, the source has to be a a pointer to a ghost_sparsemat_src_rowfunc and srcType has to be set to GHOST_SPARSEMAT_SRC_FILE.
If the flag GHOST_CONTEXT_WORKDIST_NZE is set in the flags, the source may be of any type (except GHOST_SPARSEMAT_SRC_NONE of course)

In all other cases, i.e., gnrows and gncols are correctly set and the distribution of matrix rows across ranks should be done by the number of rows, the matrixSource parameter will be ignored.

Each rank will get a portion of work which depends on the distribution scheme as set in the flags multiplied with the given weight divided by the sum of the weights of all ranks in the context's MPI communicator. Example: Rank A is of type GHOST_TYPE_CUDA using a GPU with a memory bandwidth of 150 GB/s and rank B is of type GHOST_TYPE_WORK using a CPU socket with a memory bandwidth of 50 GB/s. The work is to be distributed by rows and the matrix contains 8 million rows. A straight-forward distribution of work would assume a weight of 1.5 for A and 0.5 for B. Thus, A would be assigned 6 million matrix rows and B 2 million. Automatic weight determination is done using a main memory benchmark. If the bechmark results differ by less than 10% on each rank, the parallel run will be considered "homogeneous" and the weights will be fixed to 1.0

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void ghost_context_destroy ( ghost_context * ctx )

Free the context's resources.

Parameters

ctx	The context.

If the context is NULL it will be ignored.

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ghost_map* ghost_context_map	(	const ghost_context *	ctx,
		const ghost_maptype	mt
	)

Get the context's map with the given map type.

Parameters

ctx	The context.
mt	The map type.

Returns: The map corresponding to the map type.

ghost_map* ghost_context_max_map ( const ghost_context * ctx )

Get the largest map of the context.

Parameters

ctx	The context.

Returns: The map with the larger local dimension.

ghost_map* ghost_context_other_map	(	const ghost_context *	ctx,
		const ghost_maptype	mt
	)

Get the context's map which does not have the given map type.

Parameters

ctx	The context.
mt	The map type.

Returns: The map not corresponding to the map type.

ghost_error ghost_context_set_map	(	ghost_context *	ctx,
		ghost_maptype	which,
		ghost_map *	map
	)

Set a context's map.

Parameters

ctx	The context.
which	The map type to be set.
map	The map.

Returns: GHOST_SUCCESS on success or an error indicator.

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char* ghost_context_workdist_string ( ghost_context_flags_t flags )

Get the name of the work distribution scheme.

Parameters

flags The context flags.

Returns: A string holding a sensible name of the work distribution scheme.

Functions

Function Documentation