long starttime = get_time();  // Just a function to get the time
long timeslice_id = get_scheduler_timeslice();  // This is what I am looking for

do_lengthy_things();

print("Code took %d ms to run.", get_time() - starttime);

if (get_scheduler_timeslice() != timeslice_id)
  print("There was a task switch while running this code, don't wonder about the time.");