MPIIrecvvoid

MPIIrecvvoid is not a standard MPI function. In most MPI documentation and implementations, there is no function named MPIIrecvvoid. When this identifier appears in code or notes, it is usually a project-specific wrapper, a misnomer, or a custom binding rather than a portable MPI routine. The standard non-blocking receive in MPI is MPI_Irecv.

MPI_Irecv provides a non-blocking receive operation. Its buffer argument is a pointer to the memory where incoming data will be stored, and the datatype argument describes the type of each received item. The count parameter specifies how many elements of that datatype are expected. The call returns an MPI_Request, allowing the program to proceed concurrently with the communication. Completion is tested or waited for later with MPI_Test or MPI_Wait, respectively. After completion, MPI_Get_count can be used to determine how many elements were actually received if the count was a variable quantity.

In standard MPI, even when receiving into a void-like buffer, the datatype must be given to describe the data. For receiving arbitrary raw bytes, MPI_BYTE can be used as the datatype, with the count set to the number of bytes. The void* nature of the buffer is a property of C pointers; MPI itself relies on the datatype to interpret the bytes. Correct use requires matching the sender’s datatype and the receiver’s datatype and ensuring buffer capacity.

If a symbol named MPIIrecvvoid appears, it should be treated as non-portable or wrapper-specific. Its exact behavior cannot be assumed from the MPI standard, and portability across MPI implementations is not guaranteed. See also MPI_Irecv, MPI_Wait, MPI_Test, MPI_Get_count, and MPI_BYTE.