title: access to volatile variable - from LLD3
body: <p>I'm reading LDD3, chapter 7, and I got to this sentence :</p>
  
  <p>"... jiffies is declared as volatile by the kernel headers and, therefore, is fetched from memory any time some C code accesses it."</p>
  
  <p>which I don't understand...
  Can anyone pls make it more clear to me? What happens else, if a variable isn't volatile, when C code accesses it ?</p>
  
  <p>I know that volatile tells the proccessor not to do optimizations on this variable.. but what's the deal with accessing it ?</p>