It's mainly used as visualization frontend for data measured
by Cachegrind/Callgrind tools from the Valgrind package, but
there are converters for other measurement tools available.
Features
* direct support for profiles generated by Cachegrind/Callgrind
* support for arbitrary event types and derived event types
* sorted function list, with grouping according to ELF object/source
file/symbol namespace (such as C++ classes)
* correct handling of recursive cycles (similar to GProf)
* various visualization views for a selected function, such as
- treemap in caller/callee direction
- call graph around function
- source & assembly annotation