18.2.381. MPI_T_cvar_get_index

MPI_T_cvar_get_index — Query the index of a control variable from its name

18.2.381.1. SYNTAX

18.2.381.1.1. C Syntax

int MPI_T_cvar_get_index(const char* name, int* cvar_index)

18.2.381.2. INPUT PARAMETERS

name: Name of the control variable to query.

18.2.381.3. OUTPUT PARAMETERS

cvar_index: Index of the control variable.

18.2.381.4. DESCRIPTION

MPI_T_cvar_get_index can be used to retrieve the index of a control variable given its name. The name argument is provided by the caller as a null-terminated string, and the matching index is returned in cvar_index. The returned index can then be passed to other MPI tool information interface routines, such as MPI_T_cvar_get_info. Control variables in Open MPI are the same as MCA parameters.

This routine allows a tool to look up a control variable by name without iterating over the entire set of control variables. Because the number of control 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.

18.2.381.5. NOTES

Control 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.

18.2.381.6. ERRORS

MPI_T_cvar_get_index will fail if:

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