BigMPI is intended to handle all the drudgery of sending and receiving large messages in MPI.
In Jeff’s own words:
[BigMPI is an] Interface to MPI for large messages, i.e. those where the count argument exceeds
INT_MAXbut is still less than
SIZE_MAX. BigMPI is designed for the common case where one has a 64b address space and is unable to do MPI communication on more than 231 elements despite having sufficient memory to allocate such buffers.