I am trying to find a performance issue in my program and thus instrumented the code with profiling. gprof creates a flat profile like this:
Flat profile:
Each sample counts as 0.01 seconds.
% cumulative self self total
time seconds seconds calls ms/call ms/call name
27.97 4.10 4.10 std::_Deque_iterator<char, char&, char*>::_Deque_iterator(std::_Deque_iterator<char, char&, char*> const&)
6.96 5.12 1.02 std::_Deque_iterator<char, char&, char*>::difference_type std::operator-<char, char&, char*>(std::_Deque_iterator<char, char&, char*> const&, std::_Deque_iterator<char, char&, char*> const&)
5.12 5.87 0.75 std::__deque_buf_size(unsigned int)
4.23 6.49 0.62 std::_Deque_iterator<char, char&, char*>::operator+=(int)
3.41 6.99 0.50 std::deque<char, std::allocator<char> >::begin()
1.91 7.27 0.28 7896 0.04 0.04 std::vector<MyClass, std::allocator<MyClass> >::_M_insert_aux(__gnu_cxx::__normal_iterator<MyClass*, std::vector<MyClass, MyClasst> > >, MyClassconst&)
1.91 7.55 0.28 std::deque<char, std::allocator<char> >::size() const
1.91 7.83 0.28 std::_Deque_iterator<char, char&, char*>::_S_buffer_size()
followed by many lines with less time.
First question: is it a valid assumption to believe that there seems to be a problem with a std::deque? The problem is: I know we are using std::deque, but I am not aware of a usage with <char>.
If this assumption is true, it seems to make sense to look at the call stack and see where this deque is used. Howevre all entries concerning the deque<char> stuff are only called by <spontaneous>!
Just one example:
index % time self children called name
<spontaneous>
[1] 28.0 4.10 0.00 std::_Deque_iterator<char, char&, char*>::_Deque_iterator(std::_Deque_iterator<char, char&, char*> const&) [1]
Is there any way to find out more about this deque?
Thanks for any hints!
Apparently, spontaneous is what gprof uses when it can't work out the calling function. I would try recompiling all code with -pg (is it possible you missed some files?). Also, make sure you have optimisation turned on. Inlining will typically make these little functions disappear into the calling function which is generally more useful.