I/O Rank



next up previous contents
Next: Clock Synchronization Up: Environmental Inquiries Previous: Host Rank

I/O Rank

I/O inquiry The value returned for MPI_IO is the rank of a processor that can MPI_IO provide language-standard I/O facilities. For Fortran, this means that all of the Fortran I/O operations are supported (e.g., OPEN, REWIND, WRITE). For C, this means that all of the ANSI-C I/O operations are supported (e.g., fopen, fprintf, lseek).

If every process can provide language-standard I/O, then the value MPI_ANY_SOURCE will be returned. Otherwise, if the calling MPI_ANY_SOURCE process can provide language-standard I/O, then its rank will be returned. Otherwise, if some process can provide language-standard I/O then the rank of one such process will be returned. The same value need not be returned by all processes. If no process can provide language-standard I/O, then the value MPI_PROC_NULL will be MPI_PROC_NULL returned.



Jack Dongarra
Fri Sep 1 06:16:55 EDT 1995