18.2.407. MPI_T_pvar_get_index

MPI_T_pvar_get_index — Query the index of a performance variable from its name

18.2.407.1. SYNTAX

18.2.407.1.1. C Syntax

int MPI_T_pvar_get_index(const char* name, int var_class, int*
    pvar_index)

18.2.407.2. INPUT PARAMETERS

name: Name of the performance variable to query.
var_class: Class of the performance variable to query.

18.2.407.3. OUTPUT PARAMETERS

pvar_index: Index of the performance variable.

18.2.407.4. DESCRIPTION

MPI_T_pvar_get_index can be used to retrieve the index of a performance variable given its name and class. The name and var_class arguments are provided by the caller — name as a null-terminated string — and the matching index is returned in pvar_index. A performance variable is identified by the pair (name, var_class), so both must be supplied. The returned index can then be passed to other MPI tool information interface routines, such as MPI_T_pvar_get_info.

This routine allows a tool to look up a performance variable by name without iterating over the entire set of performance variables. Because the number of performance variables exposed by the implementation can change over time, this is both more convenient and lower overhead than enumerating all of the variables to find a particular one.

18.2.407.5. NOTES

Performance variable names are implementation-specific. Looking a variable up by name is therefore not portable across MPI implementations, but may be the preferred approach for a tool that targets Open MPI specifically.

18.2.407.6. ERRORS

MPI_T_pvar_get_index will fail if:

MPI_T_ERR_NOT_INITIALIZED: The MPI Tools interface is not initialized.
MPI_T_ERR_INVALID: name or pvar_index is NULL.
MPI_T_ERR_INVALID_NAME: name does not match the name of any performance variable of the specified var_class provided by the implementation at the time of the call.