title: How does idle(halt) state different then sleep state in Processor states?
body: <p>As there are 4 processor state C0-C4. but i'm not getting a difference between idle state and sleep state? </p>
  
  <ul>
  <li>will idle state maintain a cache coherent?</li>
  <li>will sleep state maintain a cache coherent?</li>
  <li>And what is stop-clock?</li>
  </ul>
  
  <p>I am asking all these question related to power saving in linux kernel?</p>