2.8 New in Version 1.8

Included in Version 1.8 of Compaq MPI is support for V1.0.1 of the ROMIO MPI-2 package from Argonne National Laboratory.

This version of ROMIO includes everything defined in the MPI-2 I/O chapter except shared file pointer functions (Section 9.4.4), split collective data access functions (Section 9.4.5), support for file interoperability (Section 9.5), I/O error handling (Section 9.7), and I/O error classes (Section 9.8). Since shared file pointer functions are not supported, the MPI_MODE_SEQUENTIAL amode to MPI_ File_open is also not supported. The subarray and distributed array datatype constructor functions from MPI-2 Chapter 4 (Sections 4.14.4 and 4.14.5) have been implemented. They are useful for accessing arrays stored in files. The functions MPI_File_f2c and MPI_File_ c2f (Section 4.12.4) also have been implemented. C, Fortran, and profiling interfaces are provided for all functions that have been implemented.

Limitations of this version of ROMIO include the following:

• The status argument is not filled in any function. Consequently, MPI_Get_count and MPI_Get_elements will not work when passed the status object from an MPI-I/O operation.
• All nonblocking I/O functions use a ROMIO-defined MPIO_ Request object instead of the usual MPI_Request object. Accordingly, the two functions, MPIO_Test and MPIO_Wait, are provided to test and wait on these MPIO_Request objects. They have the same semantics as MPI_Test and MPI_Wait.

      int MPIO_Test(MPIO_Request *request, int *flag, MPI_Status *status);
      int MPIO_Wait(MPIO_Request *request, MPI_Status *status);
  

  The usual functions MPI_Test, MPI_Wait, MPI_Testany, and so forth, will not work for nonblocking I/O.

• All functions return only two possible error codes - MPI_ SUCCESS on success and MPI_ERR_UNKNOWN on failure.