MPI\_T\_CATEGORY\_GET\_INFO(3) Open MPI MPI\_T\_CATEGORY\_GET\_INFO(3)

MPI\_T\_category\_get\_info — Query information from a category

# [SYNTAX](#SYNTAX)

## [C Syntax](#C_Syntax)

```
#include <mpi.h>
int MPI_T_category_get_info(int cat_index, char *name, int *name_len,
char *desc, int *desc_len, int *num_cvars, int *num_pvars,
int *num_categories)
```

# [INPUT PARAMETERS](#INPUT_PARAMETERS)

•

**cat\_index**: Index of the category to be queried.

# [INPUT/OUTPUT PARAMETERS](#INPUT/OUTPUT_PARAMETERS)

- **name\_len**: Length of the string and/or buffer for name.
- **desc\_len**: Length of the string and/or buffer for desc.

# [OUTPUT PARAMETERS](#OUTPUT_PARAMETERS)

- **name**: Buffer to return the string containing the name of the category.
- **desc**: Buffer to return the string containing the description of the category.
- **num\_cvars**: Number of control variables in the category.
- **num\_pvars**: Number of performance variables in the category.
- **num\_categories**: Number of categories contained in the category.

# [DESCRIPTION](#DESCRIPTION)

MPI\_T\_category\_get\_info can be used to query information from a category. The function returns the number of control variables, performance variables, and sub-categories in the queried category in the arguments *num\_cvars*, *num\_pvars*, and *num\_categories*, respectively.

# [NOTES](#NOTES)

This MPI tool interface function returns two strings. This function takes two argument for each string: a buffer to store the string, and a length which must initially specify the size of the buffer. If the length passed is n then this function will copy at most n - 1 characters of the string into the corresponding buffer and set the length to the number of characters copied - 1. If the length argument is NULL or the value specified in the length is 0 the corresponding string buffer is ignored and the string is not returned.

# [ERRORS](#ERRORS)

MPI\_T\_category\_get\_info will fail if:

- **MPI\_T\_ERR\_NOT\_INITIALIZED**: The MPI Tools interface not initialized
- **MPI\_T\_ERR\_INVALID\_INDEX**: The category index is invalid

# [Copyright](#Copyright)

2003-2026, The Open MPI Community

September 11, 2026

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Document: MPI_T_category_get_info(3) from openmpi-cuda-13.2 5.0.11-r0 (Chainguard OS)
Source: https://github.com/open-mpi/ompi