title: Get gprof to profile based on wall-clock time?
body: <p>My understanding is that by default gprof takes into account CPU time. Is there a way to get it to profile based on wall-clock time?</p>
  
  <p>My program does a lot of disk i/o, so the CPU time it uses only represents a fraction of the actual execution time. I need to know which portions of the disk i/o take up the most time.</p>