Do you also have some tools or scripts to help annotate code?
One inconvenience with this library's approach is having to modify the code to add/remove instrumentation, compared to something like GNU gprof which has compiler support and doesn't require modifying the code.
I've though about this but had yet to come up with a simple approach, perhaps something like a python script hooked to GCC-XML can do the trick, will look into that in the future.