Start a performance variable


int MPI_T_pvar_start(MPI_T_pvar_session session, MPI_T_pvar_handle handle)

Input Parameters

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


If the constant MPI_T_PVAR_ALL_HANDLES is passed in handle, the MPI implementation attempts to start all variables within the session identified by the parameter session for which handles have been allocated. In this case, the routine returns MPI_SUCCESS if all variables are started successfully, otherwise MPI_T_ERR_PVAR_NO_STARTSTOP is returned. Continuous variables and variables that are already started are ignored when MPI_T_PVAR_ALL_HANDLES is specified.

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 guarentee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible.

No error; MPI routine completed successfully.
The MPI tool information interface is not initialized.
Session argument is not valid.
The handle is invalid.
The performance variable can not be started or stopped.