Can somebody please enlighten me how to make the profiler produce any output at all? Using -jp stalls the process and nothing works. strace shows 

clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f2b01ef29f0) = ? ERESTARTNOINTR (To be restarted)
--- SIGPROF (Profiling timer expired) @ 0 (0) 

When I use a bigger sampling interval, e.g. i100, the app runs but I get no output from the profiler.