Time Sampling Problems with gprof

Question

I am attempting to profile some c++ code, compiled with g++ including the option -pg, using gprof. However, in spite of the fact that the program takes 10-15 minutes to run

Answer 1

gprof doesn't count any blocked time, like I/O or other stuff. Also "self time" typically is extremely small in any routine that does all its work in subfunctions, like if you're mostly using a library in a DLL where gprof can't see it. Check this answer.