title: What is the difference between CLOCK_MONOTONIC & CLOCK_MONOTONIC_RAW?
body: <p>According to the Linux man page under Ubuntu</p>
  
  <pre><code>CLOCK_MONOTONIC
        Clock that cannot be set and  represents  monotonic  time  since
        some unspecified starting point.
  
  CLOCK_MONOTONIC_RAW (since Linux 2.6.28; Linux-specific)
        Similar  to  CLOCK_MONOTONIC, but provides access to a raw hard‐
        ware-based time that is not subject to NTP adjustments.
  </code></pre>
  
  <p>According to the webster online dictionary Monotonic means:</p>
  
  <blockquote>
    <p>2: having the property either of never increasing or of never
    decreasing as the values of the independent variable or the subscripts
    of the terms increase.</p>
  </blockquote>
  
  <p>In other words, it won't jump backwards. I can see that this would be an important property if you were timing some code.</p>
  
  <p>However, the difference between the normal and raw version isn't clear.  Can someone shed some light into how NTP can still affect CLOCK_MONOTONIC? </p>