Sometimes debuggers and profilers are obivously broken, sometimes it's subtle and hard to spot. From my flame graphs page: CPU flame graph (partly broken) (Click for original SVG.) This is pretty common and usually goes unnoticed as the flame graph looks ok at first glance. But there are 15% of samples on the left, above "[unknown]", that are in the wrong place and missing frames. The problem is that this system has a default libc that has been compiled without frame pointers, so any stack walki...