MPI_Comm_set_info(3) on Linux
The text b8baa4c27c20, as Debian 8 (Jessie) shipped it.
Set new values for the hints of the communicator associated with comm. The call is collective on the group of comm. The info object may be different on each process, but any info entries that an implementation requires to be the same on all processes must appear with the same value in each process' info object.