Helper fuctions for applying

Functions
void	RTOp_MPI_type_signature (const int num_values, const int num_indexes, const int num_chars, int *num_entries, int block_lengths[], MPI_Aint displacements[], MPI_Datatype datatypes[])
int	RTOp_extract_reduct_obj_ext_state (const struct RTOp_RTOp *op, RTOp_ReductTarget reduct_obj, int num_values, int num_indexes, int num_chars, void *reduct_obj_ext)
int	RTOp_load_reduct_obj_ext_state (const struct RTOp_RTOp *op, const void *reduct_obj_ext, RTOp_ReductTarget reduct_obj)
int	RTOp_MPI_apply_op (MPI_Comm comm, const struct RTOp_RTOp *op, int root_rank, const int num_cols, const int num_vecs, const struct RTOp_SubVector sub_vecs[], const int num_targ_vecs, const struct RTOp_MutableSubVector sub_targ_vecs[], RTOp_ReductTarget reduct_objs[])

---

Detailed Description

reduction/transformation operations in C with MPI.

---

Function Documentation

void RTOp_MPI_type_signature (  const int  num_values, const int  num_indexes, const int  num_chars, int *  num_entries, int  block_lengths[], MPI_Aint  displacements[], MPI_Datatype  datatypes[] )

Initialize MPI compatible type signature arrays for reduction/transformation operator object instance data and reduction target object data. Parameters: num_values  [in] Number of value members num_indexes  [in] Number of index members num_chars  [in] Number of character members num_entries  [out] Number of entries in output arrays set block_lengths  [out] array (length >= RTOp_NUM_DATA_TYPES) displacements  [out] array (length >= RTOp_NUM_DATA_TYPES) datatypes  [out] array (length >= RTOp_NUM_DATA_TYPES) See the MPI function MPI_Type_struct(...) for a discription of these arrays. Definition at line 38 of file RTOpToMPI.c.

int RTOp_extract_reduct_obj_ext_state (  const struct RTOp_RTOp *  op, RTOp_ReductTarget  reduct_obj, int  num_values, int  num_indexes, int  num_chars, void *  reduct_obj_ext )

Fill a compacted representation for a reduction object. Parameters: op  [in] RTOp operator object reduct_obj  [in] Reduction object num_values  [in] Number of value members num_indexes  [in] Number of index members num_chars  [in] Number of character members reduct_obj_ext  [out] (size = sizeof(RTOp_value_type)*(3 + num_values) + sizeof(RTOp_index_type)*num_indexes + sizeof(RTOp_char_type)*num_chars). On output, this memory will be set according to as described in RTOp_reduct_op_func_ptr_t. Returns: Returns 0 if successful otherwise returns an error code. Definition at line 73 of file RTOpToMPI.c.

int RTOp_load_reduct_obj_ext_state (  const struct RTOp_RTOp *  op, const void *  reduct_obj_ext, RTOp_ReductTarget  reduct_obj )

Copy from a compacted representation for a reduction object. Parameters: op  [in] RTOp operator object reduct_obj_ext  [in] (size = sizeof(RTOp_value_type)*(3 + num_values) + sizeof(RTOp_index_type)*num_indexes + sizeof(RTOp_char_type)*num_chars) On input, this memory should be set according to as described in RTOp_reduct_op_func_ptr_t. reduct_obj  [in/out] Reduction object set to the values in reduct_obj_ext (must have been previously constructed) Returns: Returns 0 if successful otherwise returns an error code. Definition at line 102 of file RTOpToMPI.c.

int RTOp_MPI_apply_op (  MPI_Comm  comm, const struct RTOp_RTOp *  op, int  root_rank, const int  num_cols, const int  num_vecs, const struct RTOp_SubVector  sub_vecs[], const int  num_targ_vecs, const struct RTOp_MutableSubVector  sub_targ_vecs[], RTOp_ReductTarget  reduct_objs[] )

Apply a reduction operation over a set of local sub-vectors using MPI. Parameters: comm  [in] MPI communicator op  [in] reduction/transformation operator object root_rank  [in] See below num_cols  [in] The number of columns for each vector num_vecs  [in] See RTOpPack::RTOp::apply_op() sub_vecs  [in] Array (size num_targ_vecs * num_cols) of nonmutable subvectors. The vectors for each column kc begin at sub_vecs+kc*num_vecs where kc=0...num_cols-1 Can be NULL if there are no local vector elements. num_targ_vecs  [in] See RTOpPack::RTOp::apply_op() sub_targ_vecs  [in] Array (size num_targ_vecs * num_cols) of mutable subvectors. The vectors for each column kc begin at sub_vecs+kc*num_targ_vecs where kc=0...num_cols-1 Can be NULL if there are no local vector elements. reduct_objs  [in/out] Array (size num_cols) See below. If reduct_objs != NULL then on output, reduct_objs[i] will contain the reduction target over all the processes along with the reduction on input if reduct_objs[i] has already been through one or more reductions already and not reinitialized. Returns: Returns 0 if successful otherwise returns an error code. This function encapsulates a lot of the details of using MPI to perform reduction operations. For this function to work properly, each processor must contain a single sub-vector for each vector argument and every process (in the communicator) must call this function. Each process's sub-vector for each vector argument may be a different size and even dense on some processes and sparse in others. It is also allowed for a process to have empty sub-vectors, but still needs to participate in the collective operation and may want the value of the reduction object returned. The main responsibly of the client is to setup the sub_vecs[] and sub_targ_vecs[] arguments and to deside what type of reduction operation to perform (MPI_Allreduce() or MPI_Reduce()). Let rank be the value returned from MPI_Comm_rank(comm,&rank) in this process. The expected arguments to this function depend on the argument root_rank and rank as follows: root_rank < 0 : In this case we are performing a MPI_Allreduce(...) reduction operation over all of the processes with the results collected in all of the processes. In this case reduct_obj!=RTOp_REDUCT_OBJ_NULL must be true in all of the processes. root_rank < 0 in all processes reduct_obj != RTOp_REDUCT_OBJ_NULL in all processes if a reduction is being performed. root_rank >= 0 : In this case we are performing a MPI_Reduce(...) reduction operation over all of the processes with the result only collected in the process with rank root_rank. Here all of the processes must pass the same value for root_rank. The reduction target object is only passed in for the processes with rank == root_rank. root_rank same in all of the processes If rank == root_rank then reduct_obj != RTOp_REDUCT_OBJ_NULL If rank != root_rank then reduct_obj == RTOp_REDUCT_OBJ_NULL Note that if a reduction operation is not performed then no synchronization of the the processes are performed. This is the fastest behavior and should be fine for a single thread but may cause problems with multiple threads. Definition at line 129 of file RTOpToMPI.c.

---