A set of attributes that describe the execution environment are attached to the communicator MPI_COMM_WORLD when MPI is initialized. MPI_COMM_WORLD The value of these attributes can be inquired by using the function MPI_ATTR_GET described in Chapter . It is erroneous to delete these attributes, free their keys, or change their values.
The list of predefined attribute keys include predefined attributesattribute, predefined
Vendors may add implementation specific parameters (such as node number, real memory size, virtual memory size, etc.)
These predefined attributes do not change value between MPI initialization (MPI_INIT) and MPI completion (MPI_FINALIZE).
Advice to users. Note that in the C binding, the value returned by these attributes is a pointer to an int containing the requested value. (End of advice to users)The required parameter values are discussed in more detail below: