MPI_Comm_set_info(3) on Linux
The text ac1ab2f98d41, as Debian 10 (Buster) 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.