Inaccuracy in gprof output

Question

I am trying to profile a c++ function using gprof, I am intrested in the %time taken. I did more than one run and for some reason I got a large difference in the results. I

Answer 1

gprof is not very accurate, particularly for small functions, see http://www.cs.utah.edu/dept/old/texinfo/as/gprof.html#SEC11

If this is Linux then I recommend a profiler that doesn't require the code to be instrumented, e.g. Zoom - you can get a free 30 day evaluation license, after that it costs money.

All sampling profilers suffer form statistical inaccuracies - if the error is too large then you need to sample for longer and/or with a smaller sampling interval.