Where inputs or outputs are pointers to scalar types, both the pointer and the contents will be traced. To avoid any extra overhead of checking for NULL pointers, the trace code will only trace contents for pointers that are either required to be non-NULL by the API spec. or already have appropriate checks in the library. The contents of aggregate types will not be traced unless the entire object is passed in as an argument.
In general, there will be two trace hooks per API. The first will trace the input parameters and the second will trace the output values as well as the time interval of the API call. The performance hooks will generally have entry and exit hooks so the post-processing tools can show the time deltas. Note that the performance hooks are also debug hooks and will be enabled when either category is enabled.