These programs perform exactly the same routines as their standard HDF counterparts, but they have been augmented by instrumentation software , attached before and after the call itself, to capture internal data.
Programmers compile their instrumented source code and link it with the trace library.
During program execution, perfomance data captured by the instrumentation is recorded in SDDF files. Analysts use Pablo analysis tools to study these SDDF files and understand how HDF behaves and interacts with other system components. In profiling the performance of an application's HDF behavior, Pablo tools track, or trace , the HDF events that take place during program execution. An event, in this context, occurs each time a specific HDF function is executed. When the HDF library is compiled with the special Pablo tracing option, calls to Pablo Tracelibrary routines, which are the trace library versions of the corresponding HDF calls or commands, are made on entry to HDF routines and just prior to exiting them.