The set of instances for performance metrics returned from a pmFetch(3) call may be filtered or
restricted using an instance profile. There is one instance profile for each context the application
creates at the Performance Metrics Application Programming Interface (PMAPI(3)), and each instance
profile may include instances from one or more instance domains (see pmLookupDesc(3)).
pmAddProfile may be used to add new instance specifications to the instance profile of the current PMAPI
context.
In the simplest variant, the list of instances identified by the instlist argument for the indom instance
domain are added to the instance profile. The list of instance identifiers contains numinst values.
The indom value would normally be extracted from a call to pmLookupDesc(3) for a particular performance
metric, and the instances in instlist would typically be determined by calls to pmGetInDom(3) or
pmLookupInDom(3).
To select all instances in all instance domains, use
pmAddProfile(PM_INDOM_NULL, 0, (int *)0)
This is the only case where indom may be equal to PM_INDOM_NULL. If numinst is zero, or instlist is
NULL, then all instances in indom are selected.