typedef struct s_smpi_subtype{
void (*serialize)(const void * input, void *output, size_t count, void* subtype);
void (*unserialize)(const void * input, void *output, size_t count, void* subtype);
+ void (*subtype_free)(MPI_Datatype* type);
} s_smpi_subtype_t;
typedef struct s_smpi_mpi_datatype{