# 18.2.365. MPI_T_pvar_read

MPI_T_pvar_read — Read the value of a performance variable

## 18.2.365.1. SYNTAX

### 18.2.365.1.1. C Syntax

    #include <mpi.h>

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

## 18.2.365.2. INPUT PARAMETERS

- `session`: Performance experiment session.

- `handle`: Performance variable handle.

- `buf`: Initial address of storage location for variable value.

## 18.2.365.3. DESCRIPTION

MPI_T_pvar_read queries the value of a performance variable identified by the handle specified in handle in the session specified in session. The result is stored in the buffer pointed to by buf. The caller must ensure that the buffer pointed to by buf is large enough to hold the entire value of the performance variable.

## 18.2.365.4. ERRORS

MPI_T_pvar_read will fail if:

- `MPI_T_ERR_NOT_INITIALIZED`: The MPI Tools interface not initialized

- `MPI_T_ERR_INVALID_HANDLE`: The handle is invalid or not associated with the session

- `MPI_T_ERR_INVALID_SESSION`: Session argument is not a valid session

See also

- MPI_T_pvar_handle_alloc

- MPI_T_pvar_get_info

- MPI_T_pvar_session_create