9.4.4 Data Access with Shared File Pointers

MPI-/ maintains exactly one shared file pointer per collective MPI_FILE_OPEN (shared among processes in the communicator group). The current value of this pointer implicitly specifies the offset in the data access routines described in this section. These routines only use and update the shared file pointer maintained by MPI-/. The individual file pointers are not used nor updated.

The shared file pointer routines have the same semantics as the data access with explicit offset routines described in Section 9.4.2, page [*], with the following modifications:

For the noncollective shared file pointer routines, the serialization ordering is not deterministic. The user needs to use other synchronization means to enforce a specific order.

After a shared file pointer operation is initiated, the shared file pointer is updated to point to the next etype after the last one that will be accessed. The file pointer is updated relative to the current view of the file.



Subsections
MPI-Standard for MARMOT