Read the value of a performance variable


int MPI_T_pvar_read(MPI_T_pvar_session session, MPI_T_pvar_handle handle,
                    void *buf)

Input Parameters

identifier of performance experiment session (handle)
handle of a performance variable (handle)

Output Parameters

initial address of storage location for variable value (choice)


The MPI_T_pvar_read() call queries the value of the performance variable with the handle "handle" in the session identified by the parameter session and stores the result in the buffer identified by the parameter buf. The user is responsible to ensure that the buffer is of the appropriate size to hold the entire value of the performance variable (based on the datatype and count returned by the corresponding previous calls to MPI_T_pvar_get_info() and MPI_T_pvar_handle_alloc(), respectively).

The constant MPI_T_PVAR_ALL_HANDLES cannot be used as an argument for the function MPI_T_pvar_read().

Thread and Interrupt Safety

This routine is thread-safe. This means that this routine may be safely used by multiple threads without the need for any user-provided thread locks. However, the routine is not interrupt safe. Typically, this is due to the use of memory allocation routines such as malloc or other non-MPICH runtime routines that are themselves not interrupt-safe.


All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Comm_set_errhandler (for communicators), MPI_File_set_errhandler (for files), and MPI_Win_set_errhandler (for RMA windows). The MPI-1 routine MPI_Errhandler_set may be used but its use is deprecated. The predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible.

No error; MPI routine completed successfully.
Invalid use of the interface or bad parameter values(s).
The handle is invalid.
Session argument is not valid.
The MPI tool information interface is not initialized.
Other error; use MPI_Error_string to get more information about this error code.